Professor in atomic physics at the Department of Physics at Stockholm University

Telephone: +46-8-5537-8643

Office: C4:3015

Mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

## My main research interests:

I perform experimental studies mainly of charge-transfer processes and most often for atomic and small molecular systems. I have a preference for the fundamental relatively simple questions and is fascinated by new techniques for measurements of atomic lifetimes and also by fundamental quantum mechanical effects in collisions. Recently my main focus has been on the Double ElectroStatic Ion-Ring ExpEriment (DESIREE), but I have also been involved in collision studies with polycyclic aromatic hydrocarbons (PAHs) and on formation of two-site double core holes by means of an X-ray laser (the LCLS) and in collisions.

### Recent Conferences:

I presented the DESIREE facility at the 24th CAARI in Fort Worth, Texas, USA, October 30-November 4, 2016. https://www.caari.com/

I presented the DESIREE facility at the 'Astronomdagarna' in Uppsala, Sweden, October 22-24, 2015. http://www.astro.uu.se/astro2015/

I presented the DESIREE facility at the SPARC Topical Workshop, Fodele, Greece, Sept 22-27, 2015. http://apapes.physics.uoc.gr/index_SPARC2015.php

I made the introductory plenary presentation at the 6th Workshop on Electrostatic Storage Devices, Tokyo, 08-11 June, 2015. http://esd2015.riken.jp/

I gave an invited REVIEW presentation on 'Electrostatic Storage Rings' at the Stori2014 in St Goar, Germany Sept 28 - Oct 3, 2014. https://indico.gsi.de/conferenceDisplay.py?confId=2658

I presented a Topical Overview talk on 'Molecular Physics at Low-Energy Storage Rings' at the 'Trapped Charged Particles' conference in Takamatsu, Japan 01 -05 December, 2014. http://indico2.riken.jp/indico/conferenceDisplay.py?confId=1395

## My publications:

1. K Hansen, M H Stockett, M Kaminska, R F Nascimento, E K Anderson, M Gatchell, K C Chartkunchand, G Eklund, H Zettergren, H T Schmidt and H Cederquist.
Spontaneous decay of small copper-cluster anions ${\mathrmCu}_n^{\ensuremath-}$ ($n=3\char216$), on long time scales. Phys. Rev. A 95:022511, February 2017.
URL, DOI BibTeX

@article{PhysRevA.95.022511,
title = "Spontaneous decay of small copper-cluster anions ${\mathrm{Cu}}_{n}{}^{\ensuremath{-}}$ ($n=3\char21{}6$), on long time scales",
author = "Hansen, K. and Stockett, M. H. and Kaminska, M. and Nascimento, R. F. and Anderson, E. K. and Gatchell, M. and Chartkunchand, K. C. and Eklund, G. and Zettergren, H. and Schmidt, H. T. and Cederquist, H.",
journal = "Phys. Rev. A",
volume = 95,
issue = 2,
pages = 022511,
numpages = 8,
year = 2017,
month = "Feb",
publisher = "American Physical Society",
doi = "10.1103/PhysRevA.95.022511",
}

2. K C Chartkunchand, M Kamiıfmmode \acuten\else ń\fiska, E K Anderson, M K Kristiansson, G Eklund, O M Hole, R F Nascimento, M Blom, M Björkhage, A Källberg, P Löfgren, P Reinhed, S Rosén, A Simonsson, R D Thomas, S Mannervik, V T Davis, P A Neill, J S Thompson, D Hanstorp, H Zettergren, H Cederquist and H T Schmidt.
Radiative lifetimes of the bound excited states of ${\mathrmPt}^{\ensuremath-}$. Phys. Rev. A 94:032501, September 2016.
URL, DOI BibTeX

@article{PhysRevA.94.032501,
title = "Radiative lifetimes of the bound excited states of ${\mathrm{Pt}}^{\ensuremath{-}}$",
author = {Chartkunchand, K. C. and Kami\ifmmode \acute{n}\else \'{n}\fi{}ska, M. and Anderson, E. K. and Kristiansson, M. K. and Eklund, G. and Hole, O. M. and Nascimento, R. F. and Blom, M. and Bj\"orkhage, M. and K\"allberg, A. and L\"ofgren, P. and Reinhed, P. and Ros\'en, S. and Simonsson, A. and Thomas, R. D. and Mannervik, S. and Davis, V. T. and Neill, P. A. and Thompson, J. S. and Hanstorp, D. and Zettergren, H. and Cederquist, H. and Schmidt, H. T.},
journal = "Phys. Rev. A",
volume = 94,
issue = 3,
pages = 032501,
numpages = 6,
year = 2016,
month = "Sep",
publisher = "American Physical Society",
doi = "10.1103/PhysRevA.94.032501",
}

3. M Lestinsky, V Andrianov, B Aurand, V Bagnoud, D Bernhardt, H Beyer, S Bishop, K Blaum, A Bleile, At. Borovik, F Bosch, C J Bostock, C Brandau, A Bräuning-Demian, I Bray, T Davinson, B Ebinger, A Echler, P Egelhof, A Ehresmann, M Engström, C Enss, N Ferreira, D Fischer, A Fleischmann, E Förster, S Fritzsche, R Geithner, S Geyer, J Glorius, K Göbel, O Gorda, J Goullon, P Grabitz, R Grisenti, A Gumberidze, S Hagmann, M Heil, A Heinz, F Herfurth, R Heß, P -M Hillenbrand, R Hubele, P Indelicato, A Källberg, O Kester, O Kiselev, A Knie, C Kozhuharov, S Kraft-Bermuth, T Kühl, G Lane, Yu.A. Litvinov, D Liesen, X W Ma, R Märtin, R Moshammer, A Müller, S Namba, P Neumeyer, T Nilsson, W Nörtershäuser, G Paulus, N Petridis, M Reed, R Reifarth, P Reiß, J Rothhardt, R Sanchez, M S Sanjari, S Schippers, H T Schmidt, D Schneider, P Scholz, R Schuch, M Schulz, V Shabaev, A Simonsson, J Sjöholm, Ö Skeppstedt, K Sonnabend, U Spillmann, K Stiebing, M Steck, T Stöhlker, A Surzhykov, S Torilov, E Träbert, M Trassinelli, S Trotsenko, X L Tu, I Uschmann, P M Walker, G Weber, D F A Winters, P J Woods, H Y Zhao and Y H Zhang.
Physics book: CRYRING@ESR. The European Physical Journal Special Topics 225(5):797–882, 2016.
URL, DOI BibTeX

@article{Lestinsky2016,
author = {Lestinsky, M. and Andrianov, V. and Aurand, B. and Bagnoud, V. and Bernhardt, D. and Beyer, H. and Bishop, S. and Blaum, K. and Bleile, A. and Borovik, At. and Bosch, F. and Bostock, C.J. and Brandau, C. and Br{\"a}uning-Demian, A. and Bray, I. and Davinson, T. and Ebinger, B. and Echler, A. and Egelhof, P. and Ehresmann, A. and Engstr{\"o}m, M. and Enss, C. and Ferreira, N. and Fischer, D. and Fleischmann, A. and F{\"o}rster, E. and Fritzsche, S. and Geithner, R. and Geyer, S. and Glorius, J. and G{\"o}bel, K. and Gorda, O. and Goullon, J. and Grabitz, P. and Grisenti, R. and Gumberidze, A. and Hagmann, S. and Heil, M. and Heinz, A. and Herfurth, F. and He{\ss}, R. and Hillenbrand, P.-M. and Hubele, R. and Indelicato, P. and K{\"a}llberg, A. and Kester, O. and Kiselev, O. and Knie, A. and Kozhuharov, C. and Kraft-Bermuth, S. and K{\"u}hl, T. and Lane, G. and Litvinov, Yu.A. and Liesen, D. and Ma, X.W. and M{\"a}rtin, R. and Moshammer, R. and M{\"u}ller, A. and Namba, S. and Neumeyer, P. and Nilsson, T. and N{\"o}rtersh{\"a}user, W. and Paulus, G. and Petridis, N. and Reed, M. and Reifarth, R. and Rei{\ss}, P. and Rothhardt, J. and Sanchez, R. and Sanjari, M.S. and Schippers, S. and Schmidt, H.T. and Schneider, D. and Scholz, P. and Schuch, R. and Schulz, M. and Shabaev, V. and Simonsson, A. and Sj{\"o}holm, J. and Skeppstedt, {\"O} and Sonnabend, K. and Spillmann, U. and Stiebing, K. and Steck, M. and St{\"o}hlker, T. and Surzhykov, A. and Torilov, S. and Tr{\"a}bert, E. and Trassinelli, M. and Trotsenko, S. and Tu, X.L. and Uschmann, I. and Walker, P.M. and Weber, G. and Winters, D.F.A. and Woods, P.J. and Zhao, H.Y. and Zhang, Y.H.},
title = "Physics book: CRYRING@ESR",
journal = "The European Physical Journal Special Topics",
year = 2016,
volume = 225,
number = 5,
pages = "797--882",
abstract = {The exploration of the unique properties of stored and cooled beams of highly-charged ions as provided by heavy-ion storage rings has opened novel and fascinating research opportunities in the realm of atomic and nuclear physics research. Since the late 1980s, pioneering work has been performed at the CRYRING at Stockholm (Abrahamsson et al. 1993) and at the Test Storage Ring (TSR) at Heidelberg (Baumann et al. 1988). For the heaviest ions in the highest charge-states, a real quantum jump was achieved in the early 1990s by the commissioning of the Experimental Storage Ring (ESR) at GSI Helmholtzzentrum f{\"u}r Schwerionenforschung (GSI) in Darmstadt (Franzke 1987) where challenging experiments on the electron dynamics in the strong field regime as well as nuclear physics studies on exotic nuclei and at the borderline to atomic physics were performed. Meanwhile also at Lanzhou a heavy-ion storage ring has been taken in operation, exploiting the unique research opportunities in particular for medium-heavy ions and exotic nuclei (Xia et al. 2002).},
issn = "1951-6401",
doi = "10.1140/epjst/e2016-02643-6",
url = "http://dx.doi.org/10.1140/epjst/e2016-02643-6"
}

4. Michael Wolf, Linda Giacomozzi, Michael Gatchell, Nathalie Ruette, Mark H Stockett, Henning T Schmidt, Henrik Cederquist and Henning Zettergren.
Hydrogenated pyrene: Statistical single-carbon loss below the knockout threshold. EUROPEAN PHYSICAL JOURNAL D 70(4), 2016.
DOI BibTeX

@article{ ISI:000375296200002,
author = "Wolf, Michael and Giacomozzi, Linda and Gatchell, Michael and de Ruette, Nathalie and Stockett, Mark H. and Schmidt, Henning T. and Cederquist, Henrik and Zettergren, Henning",
title = "{Hydrogenated pyrene: Statistical single-carbon loss below the knockout threshold}",
journal = "{EUROPEAN PHYSICAL JOURNAL D}",
year = "{2016}",
volume = "{70}",
number = "{4}",
month = "{APR 14}",
doi = "{10.1140/epjd/e2016-60735-3}",
article-number = "{85}",
issn = "{1434-6060}",
eissn = "{1434-6079}",
researcherid-numbers = "{Schmidt, Henning/H-6277-2016}",
unique-id = "{ISI:000375296200002}"
}

5. M Kaminska, V T Davis, O M Hole, R F Nascimento, K C Chartkunchand, M Blom, M Björkhage, A Källberg, P Löfgren, P Reinhed, S Rosén, A Simonsson, R D Thomas, S Mannervik, P A Neill, J S Thompson, H T Schmidt, H Cederquist and D Hanstorp.
Lifetime of the bound excited level in ${\mathrmNi}^{\ensuremath-}$. Phys. Rev. A 93:012512, January 2016.
URL, DOI BibTeX

@article{PhysRevA.93.012512,
title = "Lifetime of the bound excited level in ${\mathrm{Ni}}^{\ensuremath{-}}$",
author = {Kaminska, M. and Davis, V. T. and Hole, O. M. and Nascimento, R. F. and Chartkunchand, K. C. and Blom, M. and Bj\"orkhage, M. and K\"allberg, A. and L\"ofgren, P. and Reinhed, P. and Ros\'en, S. and Simonsson, A. and Thomas, R. D. and Mannervik, S. and Neill, P. A. and Thompson, J. S. and Schmidt, H. T. and Cederquist, H. and Hanstorp, D.},
journal = "Phys. Rev. A",
volume = 93,
issue = 1,
pages = 012512,
numpages = 5,
year = 2016,
month = "Jan",
publisher = "American Physical Society",
doi = "10.1103/PhysRevA.93.012512",
}

6. H T Schmidt.
Electrostatic storage rings for atomic and molecular physics. Physica Scripta 2015(T166):014063, 2015.
URL BibTeX

@article{1402-4896-2015-T166-014063,
author = "H T Schmidt",
title = "Electrostatic storage rings for atomic and molecular physics",
journal = "Physica Scripta",
volume = 2015,
number = "T166",
pages = 014063,
url = "http://stacks.iop.org/1402-4896/2015/i=T166/a=014063",
year = 2015,
abstract = "A significant number of electrostatic ion-storage rings have been built since the late 1990s or are currently in their construction or commisioning phases. In this short contribution, we attempt to supply an overview of these different facilities, while we also mention a selection of the electrostatic ion-beam traps that has been developed through the same time period and by some of the same research groups."
}

7. M H Stockett, M Gatchell, N Ruette, L Giacomozzi, T Chen, P Rousseau, S Maclot, J -Y Chesnel, L Adoui, B A Huber, U Bērziņš, H T Schmidt, H Zettergren and H Cederquist.
Isomer effects in fragmentation of Polycyclic Aromatic Hydrocarbons. International Journal of Mass Spectrometry ():-, 2015.
URL, DOI BibTeX

@article{Stockett2015,
title = "Isomer effects in fragmentation of Polycyclic Aromatic Hydrocarbons",
journal = "International Journal of Mass Spectrometry",
volume = "",
number = "",
pages = "-",
year = 2015,
note = "",
issn = "1387-3806",
doi = "http://dx.doi.org/10.1016/j.ijms.2015.09.005",
url = "http://www.sciencedirect.com/science/article/pii/S1387380615003140",
author = "M.H. Stockett and M. Gatchell and N. de Ruette and L. Giacomozzi and T. Chen and P. Rousseau and S. Maclot and J.-Y. Chesnel and L. Adoui and B.A. Huber and U. Bērziņš and H.T. Schmidt and H. Zettergren and H. Cederquist",
keywords = "Non-statistical fragmentation"
}

8. M H Stockett, M Gatchell, T Chen, N Ruette, L Giacomozzi, M Wolf, H T Schmidt, H Zettergren and H Cederquist.
Threshold Energies for Single-Carbon Knockout from Polycyclic Aromatic Hydrocarbons. The Journal of Physical Chemistry Letters 6(22):4504-4509, 2015.
URL, DOI BibTeX

@article{doi:10.1021/acs.jpclett.5b02080,
author = "M. H. Stockett and M. Gatchell and T. Chen and N. de Ruette and L. Giacomozzi and M. Wolf and H. T. Schmidt and H. Zettergren and H. Cederquist",
title = "Threshold Energies for Single-Carbon Knockout from Polycyclic Aromatic Hydrocarbons",
journal = "The Journal of Physical Chemistry Letters",
volume = 6,
number = 22,
pages = "4504-4509",
year = 2015,
doi = "10.1021/acs.jpclett.5b02080",
note = "PMID: 26523738",
url = "http://dx.doi.org/10.1021/acs.jpclett.5b02080"
}

9. M Gatchell, M H Stockett, N Ruette, T Chen, L Giacomozzi, R F Nascimento, M Wolf, E K Anderson, R Delaunay, V Vizcaino, P Rousseau, L Adoui, B A Huber, H T Schmidt, H Zettergren and H Cederquist.
Failure of hydrogenation in protecting polycyclic aromatic hydrocarbons from fragmentation. Phys. Rev. A 92:050702(R), November 2015.
URL, DOI BibTeX

@article{PhysRevA.92.050702,
title = "Failure of hydrogenation in protecting polycyclic aromatic hydrocarbons from fragmentation",
author = "Gatchell, M. and Stockett, M. H. and de Ruette, N. and Chen, T. and Giacomozzi, L. and Nascimento, R. F. and Wolf, M. and Anderson, E. K. and Delaunay, R. and Vizcaino, V. and Rousseau, P. and Adoui, L. and Huber, B. A. and Schmidt, H. T. and Zettergren, H. and Cederquist, H.",
journal = "Phys. Rev. A",
volume = 92,
issue = 5,
pages = "050702(R)",
numpages = 5,
year = 2015,
month = "Nov",
publisher = "American Physical Society",
doi = "10.1103/PhysRevA.92.050702",
}

10. Kostiantyn Kulyk, Oleksii Rebrov, Mark H Stockett, John D Alexander, Henning Zettergren, Henning T Schmidt, Richard D Thomas, Henrik Cederquist and Mats Larsson.
High-energy collisions of protonated enantiopure amino acids with a chiral target gas. International Journal of Mass Spectrometry 388():59 - 64, 2015.
URL, DOI BibTeX

@article{Kulyk201559,
title = "High-energy collisions of protonated enantiopure amino acids with a chiral target gas",
journal = "International Journal of Mass Spectrometry",
volume = 388,
number = "",
pages = "59 - 64",
year = 2015,
note = "",
issn = "1387-3806",
doi = "http://dx.doi.org/10.1016/j.ijms.2015.08.010",
url = "http://www.sciencedirect.com/science/article/pii/S1387380615002614",
author = "Kostiantyn Kulyk and Oleksii Rebrov and Mark H. Stockett and John D. Alexander and Henning Zettergren and Henning T. Schmidt and Richard D. Thomas and Henrik Cederquist and Mats Larsson",
keywords = "2-Butanol",
abstract = "Abstract We have studied the fragmentation of the singly protonated l- and d-forms of enantiomerically pure phenylalanine (Phe), tryptophan (Trp), and methionine (Met) in high-energy collisions with chiral and achiral gas targets. (S)-(+)-2-butanol, racemic (±)-2-butanol, and argon were used as target gases. At center-of-mass frame collision energy of 1 keV, it was found that all of the ions exhibit common fragmentation pathways which are independent of target chirality. For all projectile ions, the elimination of \{NH3\} and \{H2O\} + \{CO\} were found to be the main reaction channels. The observed fragmentation patterns were dominated by statistically driven processes. The energy deposited into the ions was found to be sufficient to yield multiple fragment ions, which arise from decomposition via various competitive reaction pathways."
}

11. T Chen, M Gatchell, M H Stockett, R Delaunay, A Domaracka, E R Micelotta, A G G M Tielens, P Rousseau, L Adoui, B A Huber, H T Schmidt, H Cederquist and H Zettergren.
Formation of H2 from internally heated polycyclic aromatic hydrocarbons: Excitation energy dependence. The Journal of Chemical Physics 142:144305, 2015.
URL, DOI BibTeX

@article{:/content/aip/journal/jcp/142/14/10.1063/1.4917021,
author = "Chen, T. and Gatchell, M. and Stockett, M. H. and Delaunay, R. and Domaracka, A. and Micelotta, E. R. and Tielens, A. G. G. M. and Rousseau, P. and Adoui, L. and Huber, B. A. and Schmidt, H. T. and Cederquist, H. and Zettergren, H.",
title = "Formation of H2 from internally heated polycyclic aromatic hydrocarbons: Excitation energy dependence",
journal = "The Journal of Chemical Physics",
year = 2015,
volume = 142,
pages = 144305,
url = "http://scitation.aip.org/content/aip/journal/jcp/142/14/10.1063/1.4917021",
doi = "http://dx.doi.org/10.1063/1.4917021"
}

12. E Bäckström, D Hanstorp, O M Hole, M Kaminska, R F Nascimento, M Blom, M Björkhage, A Källberg, P Löfgren, P Reinhed, S Rosén, A Simonsson, R D Thomas, S Mannervik, H T Schmidt and H Cederquist.
Storing keV Negative Ions for an Hour: The Lifetime of the Metastable ${^2P}_1/2^o$ level in ${^32\mathrmS}^-$. Phys. Rev. Lett. 114:143003, April 2015.
URL, DOI BibTeX

@article{PhysRevLett.114.143003,
title = "Storing keV Negative Ions for an Hour: The Lifetime of the Metastable ${^{2}P}_{1/2}^{o}$ level in ${^{32}\mathrm{S}}^{-}$",
author = {B\"ackstr\"om, E. and Hanstorp, D. and Hole, O. M. and Kaminska, M. and Nascimento, R. F. and Blom, M. and Bj\"orkhage, M. and K\"allberg, A. and L\"ofgren, P. and Reinhed, P. and Ros\'en, S. and Simonsson, A. and Thomas, R. D. and Mannervik, S. and Schmidt, H. T. and Cederquist, H.},
journal = "Phys. Rev. Lett.",
volume = 114,
issue = 14,
pages = 143003,
numpages = 5,
year = 2015,
month = "Apr",
publisher = "American Physical Society",
doi = "10.1103/PhysRevLett.114.143003",
}

13. M H Stockett, M Gatchell, J D Alexander, U Berzins, T Chen, K Farid, A Johansson, K Kulyk, P Rousseau, K Stochkel, L Adoui, P Hvelplund, B A Huber, H T Schmidt, H Zettergren and H Cederquist.
Fragmentation of anthracene C14H10, acridine C13H9N and phenazine C12H8N2 ions in collisions with atoms. Phys. Chem. Chem. Phys. 16:21980, 2014.
URL, DOI BibTeX

@article{C4CP03293D,
author = "Stockett, M. H. and Gatchell, M. and Alexander, J. D. and Berzins, U. and Chen, T. and Farid, K. and Johansson, A. and Kulyk, K. and Rousseau, P. and Stochkel, K. and Adoui, L. and Hvelplund, P. and Huber, B. A. and Schmidt, H. T. and Zettergren, H. and Cederquist, H.",
doi = "10.1039/C4CP03293D",
journal = "Phys. Chem. Chem. Phys.",
volume = 16,
issue = 40,
pages = 21980,
publisher = "The Royal Society of Chemistry",
title = "Fragmentation of anthracene C14H10{,} acridine C13H9N and phenazine C12H8N2 ions in collisions with atoms",
url = "http://dx.doi.org/10.1039/C4CP03293D",
year = 2014,
bdsk-url-1 = "http://dx.doi.org/10.1039/C4CP03293D"
}

14. M Gatchell, P Rousseau, A Domaracka, M H Stockett, T Chen, H T Schmidt, J Y Chesnel, A Méry, S Maclot, L Adoui, B A Huber, H Zettergren and H Cederquist.
Ions colliding with mixed clusters of C60 and coronene: Fragmentation and bond formation. Phys. Rev. A 90:022713, 2014.
URL, DOI BibTeX

@article{PhysRevA.90.022713,
title = "Ions colliding with mixed clusters of C60 and coronene: Fragmentation and bond formation",
author = "Gatchell, M. and Rousseau, P. and Domaracka, A. and Stockett, M. H. and Chen, T. and Schmidt, H. T. and Chesnel, J. Y. and M\'ery, A. and Maclot, S. and Adoui, L. and Huber, B. A. and Zettergren, H. and Cederquist, H.",
journal = "Phys. Rev. A",
volume = 90,
issue = 2,
pages = 022713,
numpages = 7,
year = 2014,
publisher = "American Physical Society",
doi = "10.1103/PhysRevA.90.022713",
}

15. T Chen, M Gatchell, M H Stockett, J D Alexander, Y Zhang, P Rousseau, A Domaracka, S Maclot, R Delaunay, L Adoui, B A Huber, T Schlathölter, H T Schmidt, H Cederquist and H Zettergren.
Absolute fragmentation cross sections in atom-molecule collisions: Scaling laws for non-statistical fragmentation of polycyclic aromatic hydrocarbon molecules. The Journal of Chemical Physics 140(22):-, 2014.
URL, DOI BibTeX

@article{:/content/aip/journal/jcp/140/22/10.1063/1.4881603,
author = {Chen, T. and Gatchell, M. and Stockett, M. H. and Alexander, J. D. and Zhang, Y. and Rousseau, P. and Domaracka, A. and Maclot, S. and Delaunay, R. and Adoui, L. and Huber, B. A. and Schlath{\"o}lter, T. and Schmidt, H. T. and Cederquist, H. and Zettergren, H.},
doi = "http://dx.doi.org/10.1063/1.4881603",
eid = 224306,
journal = "The Journal of Chemical Physics",
number = 22,
pages = "-",
title = "Absolute fragmentation cross sections in atom-molecule collisions: Scaling laws for non-statistical fragmentation of polycyclic aromatic hydrocarbon molecules",
url = "http://scitation.aip.org/content/aip/journal/jcp/140/22/10.1063/1.4881603",
volume = 140,
year = 2014,
bdsk-url-1 = "http://scitation.aip.org/content/aip/journal/jcp/140/22/10.1063/1.4881603",
bdsk-url-2 = "http://dx.doi.org/10.1063/1.4881603"
}

16. M Gatchell, M H Stockett, P Rousseau, T Chen, K Kulyk, H T Schmidt, J Y Chesnel, A Domaracka, A Méry, S Maclot, L Adoui, K Støchkel, P Hvelplund, Y Wang, M Alcamí, B A Huber, F Martín, H Zettergren and H Cederquist.
Non-statistical fragmentation of PAHs and fullerenes in collisions with atoms. International Journal of Mass Spectrometry 365–366:260 - 265, 2014.
URL, DOI BibTeX

@article{Gatchell2014260,
author = "M. Gatchell and M.H. Stockett and P. Rousseau and T. Chen and K. Kulyk and H.T. Schmidt and J.Y. Chesnel and A. Domaracka and A. M{\'e}ry and S. Maclot and L. Adoui and K. St{\o}chkel and P. Hvelplund and Y. Wang and M. Alcam{\'i} and B.A. Huber and F. Mart{\'i}n and H. Zettergren and H. Cederquist",
doi = "http://dx.doi.org/10.1016/j.ijms.2013.12.013",
issn = "1387-3806",
journal = "International Journal of Mass Spectrometry",
keywords = "Non-statistical fragmentation",
note = "Special issue: Tilmann mark",
pages = "260 - 265",
title = "Non-statistical fragmentation of \{PAHs\} and fullerenes in collisions with atoms",
url = "http://www.sciencedirect.com/science/article/pii/S1387380613004491",
volume = "365--366",
year = 2014,
bdsk-url-1 = "http://www.sciencedirect.com/science/article/pii/S1387380613004491",
bdsk-url-2 = "http://dx.doi.org/10.1016/j.ijms.2013.12.013"
}

17. M H Stockett, H Zettergren, L Adoui, J D Alexander, U Berzins, T Chen, M Gatchell, N Haag, B A Huber, P Hvelplund, A Johansson, H A B Johansson, K Kulyk, S Rosén, P Rousseau, K Støchkel, H T Schmidt and H Cederquist.
Nonstatistical fragmentation of large molecules. Phys. Rev. A 89:032701, March 2014.
URL, DOI BibTeX

@article{PhysRevA.89.032701,
title = "Nonstatistical fragmentation of large molecules",
author = "Stockett, M. H. and Zettergren, H. and Adoui, L. and Alexander, J. D. and Berzins, U. and Chen, T. and Gatchell, M. and Haag, N. and Huber, B. A. and Hvelplund, P. and Johansson, A. and Johansson, H. A. B. and Kulyk, K. and Ros\'en, S. and Rousseau, P. and St\o{}chkel, K. and Schmidt, H. T. and Cederquist, H.",
journal = "Phys. Rev. A",
volume = 89,
issue = 3,
pages = 032701,
numpages = 5,
year = 2014,
month = "Mar",
publisher = "American Physical Society",
doi = "10.1103/PhysRevA.89.032701",
}

18. M Gatchell, H Zettergren, F Seitz, T Chen, J D Alexander, M H Stockett, H T Schmidt, A Ławicki, J Rangama, P Rousseau, M Capron, S Maclot, R Maisonny, A Domaracka, L Adoui, A Méry, J-Y Chesnel, B Manil, B A Huber and H Cederquist.
Ions colliding with polycyclic aromatic hydrocarbon clusters. Physica Scripta 2013(T156):014062, 2013.
URL BibTeX

@article{1402-4896-2013-T156-014062,
author = "M Gatchell and H Zettergren and F Seitz and T Chen and J D Alexander and M H Stockett and H T Schmidt and A Ławicki and J Rangama and P Rousseau and M Capron and S Maclot and R Maisonny and A Domaracka and L Adoui and A Méry and J-Y Chesnel and B Manil and B A Huber and H Cederquist",
title = "Ions colliding with polycyclic aromatic hydrocarbon clusters",
journal = "Physica Scripta",
volume = 2013,
number = "T156",
pages = 014062,
url = "http://stacks.iop.org/1402-4896/2013/i=T156/a=014062",
year = 2013,
abstract = "We have measured the ionization and fragmentation of polycyclic aromatic hydrocarbon (PAH) molecules and their clusters. We find that PAH clusters containing up to roughly 100 individual molecules fragment strongly following collisions with keV ions in low or high charge states ( q ). For both types of collisions, singly charged PAH molecules are found to be the dominant products but for very different reasons. A high- q ion projectile charge leads to strong multiple ionization of the PAH clusters and subsequent Coulomb explosions. A low- q ion projectile charge often leads to single ionization but stronger internal heating and long evaporation sequences with a singly charged PAH monomer as the end product. We have developed a Monte Carlo method for collision-induced heating of PAH clusters and present an evaporation model where the clusters cool slowly as most of the internal energies are stored in intramolecular vibrations and not in molecule–molecule vibrations."
}

19. M Larsson, P Salén, P Meulen, H T Schmidt, R D Thomas, R Feifel, M N Piancastelli, L Fang, B F Murphy, T Osipov, N Berrah, E Kukk, K Ueda, J D Bozek, C Bostedt, S Wada, R Richter, V Feyer and K C Prince.
Double core-hole formation in small molecules at the LCLS free electron laser. Journal of Physics B: Atomic, Molecular and Optical Physics 46(16):164030, 2013.
URL BibTeX

@article{0953-4075-46-16-164030,
author = "M Larsson and P Salén and P van der Meulen and H T Schmidt and R D Thomas and R Feifel and M N Piancastelli and L Fang and B F Murphy and T Osipov and N Berrah and E Kukk and K Ueda and J D Bozek and C Bostedt and S Wada and R Richter and V Feyer and K C Prince",
title = "Double core-hole formation in small molecules at the LCLS free electron laser",
journal = "Journal of Physics B: Atomic, Molecular and Optical Physics",
volume = 46,
number = 16,
pages = 164030,
url = "http://stacks.iop.org/0953-4075/46/i=16/a=164030",
year = 2013,
abstract = "We have investigated nonlinear processes in small molecules by x-ray photoelectron spectroscopy using the Linac Coherent Light Source free electron laser, and by simulations. The main focus of the experiments was the formation of the two-site double core-hole (tsDCH) states in the molecules CO 2 , N 2 O and N 2 . These experiments are described in detail and the results are compared with simulations of the photoelectron spectra. The double core-hole states, and in particular the tsDCH states, have been predicted to be highly sensitive to the chemical environment. The theory behind this chemical sensitivity is validated by the experiments. Furthermore, our simulations of the relative integrated intensities of the peaks associated with the nonlinear processes show that this type of simulation, in combination with experimental data, provides a useful tool for estimating the duration of ultra-short x-ray pulses."
}

20. F Seitz, H Zettergren, P Rousseau, Y Wang, T Chen, M Gatchell, J D Alexander, M H Stockett, J Rangama, J Y Chesnel, M Capron, J C Poully, A Domaracka, A Mery, S Maclot, V Vizcaino, H T Schmidt, L Adoui, M Alcami, A G G M Tielens, F Martin, B A Huber and H Cederquist.
Ions colliding with clusters of fullerenes–-Decay pathways and covalent bond formations. The Journal of Chemical Physics 139(3):034309, 2013.
URL, DOI BibTeX

@article{seitz:034309,
author = "F. Seitz and H. Zettergren and P. Rousseau and Y. Wang and T. Chen and M. Gatchell and J. D. Alexander and M. H. Stockett and J. Rangama and J. Y. Chesnel and M. Capron and J. C. Poully and A. Domaracka and A. Mery and S. Maclot and V. Vizcaino and H. T. Schmidt and L. Adoui and M. Alcami and A. G. G. M. Tielens and F. Martin and B. A. Huber and H. Cederquist",
collaboration = "",
title = "Ions colliding with clusters of fullerenes---Decay pathways and covalent bond formations",
publisher = "AIP",
year = 2013,
journal = "The Journal of Chemical Physics",
volume = 139,
number = 3,
eid = 034309,
numpages = 8,
pages = 034309,
keywords = "argon; bonds (chemical); charge exchange; evaporation; excited states; fullerenes; helium ions; ionisation; ion-molecule collisions; ion-molecule reactions; molecular clusters; molecular dynamics method; Monte Carlo methods; positive ions; van der Waals forces; xenon",
url = "/images/articles/Cov_bond_form_JCP.html",
doi = "10.1063/1.4812790"
}

21. H T Schmidt, R D Thomas, M Gatchell, S Rosén, P Reinhed, P Löfgren, L Brännholm, M Blom, M Björkhage, E Bäckström, J D Alexander, S Leontein, D Hanstorp, H Zettergren, L Liljeby, A Källberg, A Simonsson, F Hellberg, S Mannervik, M Larsson, W D Geppert, K G Rensfelt, H Danared, A Paál, M Masuda, P Halldén, G Andler, M H Stockett, T Chen, G Källersjö, J Weimer, K Hansen, H Hartman and H Cederquist.
First storage of ion beams in the Double Electrostatic Ion-Ring Experiment: DESIREE. Review of Scientific Instruments 84(5):055115, 2013.
URL, DOI BibTeX

@article{schmidt:055115,
author = {H. T. Schmidt and R. D. Thomas and M. Gatchell and S. Ros\'{e}n and P. Reinhed and P. L\"{o}fgren and L. Br\"{a}nnholm and M. Blom and M. Bj\"{o}rkhage and E. B\"{a}ckstr\"{o}m and J. D. Alexander and S. Leontein and D. Hanstorp and H. Zettergren and L. Liljeby and A. K\"{a}llberg and A. Simonsson and F. Hellberg and S. Mannervik and M. Larsson and W. D. Geppert and K. G. Rensfelt and H. Danared and A. Pa\'{a}l and M. Masuda and P. Halld\'{e}n and G. Andler and M. H. Stockett and T. Chen and G. K\"{a}llersj\"{o} and J. Weimer and K. Hansen and H. Hartman and H. Cederquist},
collaboration = "",
title = "First storage of ion beams in the Double Electrostatic Ion-Ring Experiment: DESIREE",
publisher = "AIP",
year = 2013,
journal = "Review of Scientific Instruments",
volume = 84,
number = 5,
eid = 055115,
numpages = 6,
pages = 055115,
keywords = "ion accelerators; ion beams; particle beam injection; space charge; storage rings",
url = "/images/articles/DESIREE_Comm_RSI.html",
doi = "10.1063/1.4807702"
}

22. H Zettergren, P Rousseau, Y Wang, F Seitz, T Chen, M Gatchell, J D Alexander, M H Stockett, J Rangama, J Y Chesnel, M Capron, J C Poully, A Domaracka, A Mery, S Maclot, H T Schmidt, L Adoui, M Alcami, A G G M Tielens, F Martin, B A Huber and H Cederquist.
Formations of Dumbbell C118 and C119 inside Clusters of C60 Molecules by Collision with alpha Particles. Phys. Rev. Lett. 110:185501, May 2013.
URL, DOI BibTeX

@article{PhysRevLett.110.185501,
title = "Formations of Dumbbell C118 and C119 inside Clusters of C60 Molecules by Collision with alpha Particles",
author = "Zettergren, H. and Rousseau, P. and Wang, Y. and Seitz, F. and Chen, T. and Gatchell, M. and Alexander, J. D. and Stockett, M. H. and Rangama, J. and Chesnel, J. Y. and Capron, M. and Poully, J. C. and Domaracka, A. and Mery, A. and Maclot, S. and Schmidt, H. T. and Adoui, L. and Alcami, M. and Tielens, A. G. G. M. and Martin, F. and Huber, B. A. and Cederquist, H.",
journal = "Phys. Rev. Lett.",
volume = 110,
issue = 18,
pages = 185501,
numpages = 5,
year = 2013,
month = "May",
doi = "10.1103/PhysRevLett.110.185501",
publisher = "American Physical Society"
}

23. P Rousseau, A Lawicki, A I S Holm, M Capron, R Maisonny, S Maclot, E Lattouf, H A B Johansson, F Seitz, A Mery, J Rangama, H Zettergren, S Rosen, H T Schmidt, J -Y Chesnel, A Domaracka, B Manil, L Adoui, H Cederquist and B A Huber.
Low-energy ions interacting with anthracene molecules and clusters. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 279:140-143, 2012.
DOI BibTeX

@article{ ISI:000303637500033,
author = "Rousseau, P. and Lawicki, A. and Holm, A. I. S. and Capron, M. and Maisonny, R. and Maclot, S. and Lattouf, E. and Johansson, H. A. B. and Seitz, F. and Mery, A. and Rangama, J. and Zettergren, H. and Rosen, S. and Schmidt, H. T. and Chesnel, J. -Y. and Domaracka, A. and Manil, B. and Adoui, L. and Cederquist, H. and Huber, B. A.",
title = "{Low-energy ions interacting with anthracene molecules and clusters}",
journal = "{NUCLEAR INSTRUMENTS \& METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS}",
year = "{2012}",
volume = "{279}",
pages = "{140-143}",
month = "{MAY 15}",
note = "{5th International Conference on Elementary Processes in Atomic Systems (CEPAS), Belgrade, SERBIA, JUN 21-25, 2011}",
organization = "{Univ Belgrade, Inst Phys; Serbian Acad Sci \& Arts (SASA); Republ Serbia, Minist Educ \& Sci; Serbian Phys Soc; Serv Cooperat dact culturelle Ambassade France Serbie; Osterreichisches Kulturforum Belgrad}",
abstract = "{The interaction of slow ions (nu similar to 0.4 au.) with a small polycyclic aromatic hydrocarbon, namely anthracene (C14H10), is studied in the gas-phase either with the isolated molecule or with a pure cluster target. We discuss the ionization and fragmentation of the molecule with respect to the projectile charge state, i.e. for singly charged He+ ions and for multiply charged Xe20+. ions. For the isolated C14H10, single or multiple ionization of the molecule occurs under ion impact. The (multi) cation relative yields are compared with those obtained by other ionization methods (electron and fs-laser). The molecular dissociation occurs by loss of hydrogen and small hydrocarbon molecules, leading to the formation of CnHx cations. The interaction of Xe20+ with C14H10 clusters gives surprising results, i.e. the emission of hotter monomer compared to the interaction with He+. (C) 2011 Elsevier B.V. All rights reserved.}",
doi = "{10.1016/j.nimb.2011.10.050}",
issn = "{0168-583X}",
unique-id = "{ISI:000303637500033}"
}

24. P Salen, P Meulen, H T Schmidt, R D Thomas, M Larsson, R Feifel, M N Piancastelli, L Fang, B Murphy, T Osipov, N Berrah, E Kukk, K Ueda, J D Bozek, C Bostedt, S Wada, R Richter, V Feyer and K C Prince.
Experimental Verification of the Chemical Sensitivity of Two-Site Double Core-Hole States Formed by an X-Ray Free-Electron Laser (vol 108, 153003, 2012). PHYSICAL REVIEW LETTERS 108(19), 2012.
DOI BibTeX

@article{ ISI:000303909400022,
author = "Salen, P. and van der Meulen, P. and Schmidt, H. T. and Thomas, R. D. and Larsson, M. and Feifel, R. and Piancastelli, M. N. and Fang, L. and Murphy, B. and Osipov, T. and Berrah, N. and Kukk, E. and Ueda, K. and Bozek, J. D. and Bostedt, C. and Wada, S. and Richter, R. and Feyer, V. and Prince, K. C.",
title = "{Experimental Verification of the Chemical Sensitivity of Two-Site Double Core-Hole States Formed by an X-Ray Free-Electron Laser (vol 108, 153003, 2012)}",
journal = "{PHYSICAL REVIEW LETTERS}",
year = "{2012}",
volume = "{108}",
number = "{19}",
month = "{MAY 11}",
doi = "{10.1103/PhysRevLett.108.199903}",
article-number = "{199903}",
issn = "{0031-9007}",
researcherid-numbers = "{Bozek, John/E-9260-2010}",
unique-id = "{ISI:000303909400022}"
}

25. P Salen, P Meulen, H T Schmidt, R D Thomas, M Larsson, R Feifel, M N Piancastelli, L Fang, B Murphy, T Osipov, N Berrah, E Kukk, K Ueda, J D Bozek, C Bostedt, S Wada, R Richter, V Feyer and K C Prince.
Experimental Verification of the Chemical Sensitivity of Two-Site Double Core-Hole States Formed by an X-Ray Free-Electron Laser. PHYSICAL REVIEW LETTERS 108(15), 2012.
DOI BibTeX

@article{ ISI:000302797400004,
author = "Salen, P. and van der Meulen, P. and Schmidt, H. T. and Thomas, R. D. and Larsson, M. and Feifel, R. and Piancastelli, M. N. and Fang, L. and Murphy, B. and Osipov, T. and Berrah, N. and Kukk, E. and Ueda, K. and Bozek, J. D. and Bostedt, C. and Wada, S. and Richter, R. and Feyer, V. and Prince, K. C.",
title = "{Experimental Verification of the Chemical Sensitivity of Two-Site Double Core-Hole States Formed by an X-Ray Free-Electron Laser}",
journal = "{PHYSICAL REVIEW LETTERS}",
year = "{2012}",
volume = "{108}",
number = "{15}",
month = "{APR 13}",
abstract = "{We have performed x-ray two-photon photoelectron spectroscopy using the Linac Coherent Light Source x-ray free-electron laser in order to study double core-hole (DCH) states of CO2, N2O, and N-2. The experiment verifies the theory behind the chemical sensitivity of two-site DCH states by comparing a set of small molecules with respect to the energy shift of the two-site DCH state and by extracting the relevant parameters from this shift.}",
doi = "{10.1103/PhysRevLett.108.153003}",
article-number = "{153003}",
issn = "{0031-9007}",
researcherid-numbers = "{Bozek, John/E-9260-2010 Feifel, Raimund/A-4441-2009}",
unique-id = "{ISI:000302797400004}"
}

26. Nora Berrah, Li Fang, Brendan Murphy, Timur Osipov, Kiyoshi Ueda, Edwin Kukk, Raimund Feifel, Peter Meulen, Peter Salen, Henning T Schmidt, Richard D Thomas, Mats Larsson, Robert Richter, Kevin C Prince, John D Bozek, Christoph Bostedt, Shin-ichi Wada, Maria N Piancastelli, Motomichi Tashiro and Masahiro Ehara.
Double-core-hole spectroscopy for chemical analysis with an intense X-ray femtosecond laser. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 108(41):16912-16915, 2011.
DOI BibTeX

@article{ ISI:000295973800015,
author = "Berrah, Nora and Fang, Li and Murphy, Brendan and Osipov, Timur and Ueda, Kiyoshi and Kukk, Edwin and Feifel, Raimund and van der Meulen, Peter and Salen, Peter and Schmidt, Henning T. and Thomas, Richard D. and Larsson, Mats and Richter, Robert and Prince, Kevin C. and Bozek, John D. and Bostedt, Christoph and Wada, Shin-ichi and Piancastelli, Maria N. and Tashiro, Motomichi and Ehara, Masahiro",
title = "{Double-core-hole spectroscopy for chemical analysis with an intense X-ray femtosecond laser}",
journal = "{PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}",
year = "{2011}",
volume = "{108}",
number = "{41}",
pages = "{16912-16915}",
month = "{OCT 11}",
abstract = "{Theory predicts that double-core-hole (DCH) spectroscopy can provide a new powerful means of differentiating between similar chemical systems with a sensitivity not hitherto possible. Although DCH ionization on a single site in molecules was recently measured with double-and single-photon absorption, double-core holes with single vacancies on two different sites, allowing unambiguous chemical analysis, have remained elusive. Here we report that direct observation of double-core holes with single vacancies on two different sites produced via sequential two-photon absorption, using short, intense X-ray pulses from the Linac Coherent Light Source free-electron laser and compare it with theoretical modeling. The observation of DCH states, which exhibit a unique signature, and agreement with theory proves the feasibility of the method. Our findings exploit the ultrashort pulse duration of the free-electron laser to eject two core electrons on a time scale comparable to that of Auger decay and demonstrate possible future X-ray control of physical inner-shell processes.}",
doi = "{10.1073/pnas.1111380108}",
issn = "{0027-8424}",
researcherid-numbers = "{Tashiro, Motomichi/B-2699-2010 Feifel, Raimund/A-4441-2009 Bozek, John/E-9260-2010}",
orcid-numbers = "{Tashiro, Motomichi/0000-0001-6039-4118 }",
unique-id = "{ISI:000295973800015}"
}

27. H A B Johansson, H Zettergren, A I S Holm, F Seitz, H T Schmidt, P Rousseau, A Lawicki, M Capron, A Domaracka, E Lattouf, S Maclot, R Maisonny, B Manil, J -Y Chesnel, L Adoui, B A Huber and H Cederquist.
Ionization and fragmentation of polycyclic aromatic hydrocarbon clusters in collisions with keV ions. PHYSICAL REVIEW A 84(4), 2011.
DOI BibTeX

@article{ ISI:000295712700013,
author = "Johansson, H. A. B. and Zettergren, H. and Holm, A. I. S. and Seitz, F. and Schmidt, H. T. and Rousseau, P. and Lawicki, A. and Capron, M. and Domaracka, A. and Lattouf, E. and Maclot, S. and Maisonny, R. and Manil, B. and Chesnel, J. -Y. and Adoui, L. and Huber, B. A. and Cederquist, H.",
title = "{Ionization and fragmentation of polycyclic aromatic hydrocarbon clusters in collisions with keV ions}",
journal = "{PHYSICAL REVIEW A}",
year = "{2011}",
volume = "{84}",
number = "{4}",
month = "{OCT 10}",
abstract = "{We report on an experimental study of the ionization and fragmentation of clusters of k polycyclic aromatic hydrocarbon (PAH) molecules using anthracene, C14H10, or coronene, C24H12. These PAH clusters are moderately charged and strongly heated in small impact parameter collisions with 22.5-keV He2+ ions, after which they mostly decay in long monomer evaporation sequences with singly charged and comparatively cold monomers as dominating end products. We describe a simple cluster evaporation model and estimate the number of PAH molecules in the clusters that have to be hit by He2+ projectiles for such complete cluster evaporations to occur. Highly charged and initially cold clusters are efficiently formed in collisions with 360-keV Xe20+ ions, leading to cluster Coulomb explosions and several hot charged fragments, which again predominantly yield singly charged, but much hotter, monomer ions than the He2+ collisions. We present a simple formula, based on density-functional-theory calculations, for the ionization energy sequences as functions of coronene cluster size, rationalized in terms of the classic electrostatic expression for the ionization of a charged conducting object. Our analysis indicates that multiple electron removal by highly charged ions from a cluster of PAH molecules rapidly may become more important than single ionization as the cluster size k increases and that this is the main reason for the unexpectedly strong heating in these types of collisions.}",
doi = "{10.1103/PhysRevA.84.043201}",
article-number = "{043201}",
issn = "{1050-2947}",
unique-id = "{ISI:000295712700013}"
}

28. M Gudmundsson, D Fischer, D Misra, A Kallberg, A Simonsson, K Stochkel, H Cederquist and H T Schmidt.
Two-site double-core-hole states formed when fast protons capture electrons from aligned N-2. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS 44(17), 2011.
DOI BibTeX

@article{ ISI:000294891500009,
author = "Gudmundsson, M. and Fischer, D. and Misra, D. and Kallberg, A. and Simonsson, A. and Stochkel, K. and Cederquist, H. and Schmidt, H. T.",
title = "{Two-site double-core-hole states formed when fast protons capture electrons from aligned N-2}",
journal = "{JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS}",
year = "{2011}",
volume = "{44}",
number = "{17}",
month = "{SEP 14}",
abstract = "{We report on an experimental investigation of 1.04 MeV H++N-2 electron transfer collisions. The fast protons were stored in the electron-cooler ion-storage ring, CRYRING, and the molecular nitrogen target was provided with a supersonic gas jet. We report momentum distributions of atomic nitrogen dissociation products Nq+ with charge states q+ (q = 1, 2, 3) which are detected in coincidence with neutralized projectiles. Further, we investigate the influence of the angle between the direction of the incoming projectile beam and the target molecular axis. The orientation of the latter is determined from the momentum vector of one emitted atomic nitrogen fragment ion. We find significantly higher total yields, dominated by N+, of charged atomic dissociation products when the N-2 molecular axis is perpendicular to the incoming H+-beam. The relative contributions from N2+- and N3+-fragments, however, are strongest when the N-2 axis is aligned-or close to aligned-with the ion beam. This, we suggest, is due to increased probabilities for the formation of two-site double-core-hole states.}",
doi = "{10.1088/0953-4075/44/17/175201}",
article-number = "{175201}",
issn = "{0953-4075}",
researcherid-numbers = "{Misra, Deepankar/C-8813-2009}",
unique-id = "{ISI:000294891500009}"
}

29. H A B Johansson, H Zettergren, A I S Holm, N Haag, Brondsted S Nielsen, J A Wyer, M -B S Kirketerp, K Stochkel, P Hvelplund, H T Schmidt and H Cederquist.
Unimolecular dissociation of anthracene and acridine cations: The importance of isomerization barriers for the C2H2 loss and HCN loss channels. JOURNAL OF CHEMICAL PHYSICS 135(8), 2011.
DOI BibTeX

@article{ ISI:000294484700036,
author = "Johansson, H. A. B. and Zettergren, H. and Holm, A. I. S. and Haag, N. and Nielsen, S. Brondsted and Wyer, J. A. and Kirketerp, M. -B. S. and Stochkel, K. and Hvelplund, P. and Schmidt, H. T. and Cederquist, H.",
title = "{Unimolecular dissociation of anthracene and acridine cations: The importance of isomerization barriers for the C2H2 loss and HCN loss channels}",
journal = "{JOURNAL OF CHEMICAL PHYSICS}",
year = "{2011}",
volume = "{135}",
number = "{8}",
month = "{AUG 28}",
abstract = "{The loss of C2H2 is a low activation energy dissociation channel for anthracene (C14H10) and acridine (C13H9N) cations. For the latter ion another prominent fragmentation pathway is the loss of HCN. We have studied these two dissociation channels by collision induced dissociation experiments of 50 keV anthracene cations and protonated acridine, both produced by electrospray ionization, in collisions with a neutral xenon target. In addition, we have carried out density functional theory calculations on possible reaction pathways for the loss of C2H2 and HCN. The mass spectra display features of multi-step processes, and for protonated acridine the dominant first step process is the loss of a hydrogen from the N site, which then leads to C2H2/HCN loss from the acridine cation. With our calculations we have identified three pathways for the loss of C2H2 from the anthracene cation, with three different cationic products: 2-ethynylnaphthalene, biphenylene, and acenaphthylene. The third product is the one with the overall lowest dissociation energy barrier. For the acridine cation our calculated pathway for the loss of C2H2 leads to the 3-ethynylquinoline cation, and the loss of HCN leads to the biphenylene cation. Isomerization plays an important role in the formation of the non-ethynyl containing products. All calculated fragmentation pathways should be accessible in the present experiment due to substantial energy deposition in the collisions. (C) 2011 American Institute of Physics. {[}doi:10.1063/1.3626792]}",
doi = "{10.1063/1.3626792}",
article-number = "{084304}",
issn = "{0021-9606}",
unique-id = "{ISI:000294484700036}"
}

30. F Seitz, A I S Holm, H Zettergren, H A B Johansson, S Rosen, H T Schmidt, A Lawicki, J Rangama, P Rousseau, M Capron, R Maisonny, A Domaracka, L Adoui, A Mery, B Manil, B A Huber and H Cederquist.
Polycyclic aromatic hydrocarbon-isomer fragmentation pathways: Case study for pyrene and fluoranthene molecules and clusters. JOURNAL OF CHEMICAL PHYSICS 135(6), 2011.
DOI BibTeX

@article{ ISI:000293955000012,
author = "Seitz, F. and Holm, A. I. S. and Zettergren, H. and Johansson, H. A. B. and Rosen, S. and Schmidt, H. T. and Lawicki, A. and Rangama, J. and Rousseau, P. and Capron, M. and Maisonny, R. and Domaracka, A. and Adoui, L. and Mery, A. and Manil, B. and Huber, B. A. and Cederquist, H.",
title = "{Polycyclic aromatic hydrocarbon-isomer fragmentation pathways: Case study for pyrene and fluoranthene molecules and clusters}",
journal = "{JOURNAL OF CHEMICAL PHYSICS}",
year = "{2011}",
volume = "{135}",
number = "{6}",
month = "{AUG 14}",
abstract = "{We report on measurements of the ionization and fragmentation of polycyclic aromatic hydrocarbon (PAH) targets in Xe(20+) + C(16)H(10) and Xe(20+) + {[}C(16)H(10)](k) collisions and compare results for the two C(16)H(10) isomers: pyrene and fluoranthene. For both types of targets, i.e., for single PAH molecules isolated in vacuum or for isomerically pure clusters of one of the molecules, the resulting fragment spectra are surprisingly similar. However, we do observe weak but significant isomer effects. Although these are manifested in very different ways for the monomer and cluster targets, they both have at their roots small differences (<2.5 eV) between the total binding energies of neutral, and singly and multiply charged pyrene and fluoranthene monomers. The results will be discussed in view of the density functional theory calculations of ionization and dissociation energies for fluoranthene and pyrene. A simple classical over-the-barrier model is used to estimate cross sections for single-and multiple-electron transfer between PAHs and ions. Calculated single and multiple ionization energies, and the corresponding model PAH ionization cross sections, are given. (C) 2011 American Institute of Physics. {[}doi: 10.1063/1.3622589]}",
doi = "{10.1063/1.3622589}",
article-number = "{064302}",
issn = "{0021-9606}",
unique-id = "{ISI:000293955000012}"
}

31. R D Thomas, H T Schmidt, G Andler, M Bjorkhage, M Blom, L Brannholm, E Backstrom, H Danared, S Das, N Haag, P Hallden, F Hellberg, A I S Holm, H A B Johansson, A Kallberg, G Kallersjo, M Larsson, S Leontein, L Liljeby, P Lofgren, B Malm, S Mannervik, M Masuda, D Misra, A Orban, A Paal, P Reinhed, K -G Rensfelt, S Rosen, K Schmidt, F Seitz, A Simonsson, J Weimer, H Zettergren and H Cederquist.
The double electrostatic ion ring experiment: A unique cryogenic electrostatic storage ring for merged ion-beams studies. REVIEW OF SCIENTIFIC INSTRUMENTS 82(6), June 2011.
DOI BibTeX

@article{ ISI:000292334000069,
author = "Thomas, R. D. and Schmidt, H. T. and Andler, G. and Bjorkhage, M. and Blom, M. and Brannholm, L. and Backstrom, E. and Danared, H. and Das, S. and Haag, N. and Hallden, P. and Hellberg, F. and Holm, A. I. S. and Johansson, H. A. B. and Kallberg, A. and Kallersjo, G. and Larsson, M. and Leontein, S. and Liljeby, L. and Lofgren, P. and Malm, B. and Mannervik, S. and Masuda, M. and Misra, D. and Orban, A. and Paal, A. and Reinhed, P. and Rensfelt, K. -G. and Rosen, S. and Schmidt, K. and Seitz, F. and Simonsson, A. and Weimer, J. and Zettergren, H. and Cederquist, H.",
title = "{The double electrostatic ion ring experiment: A unique cryogenic electrostatic storage ring for merged ion-beams studies}",
journal = "{REVIEW OF SCIENTIFIC INSTRUMENTS}",
year = "{2011}",
volume = "{82}",
number = "{6}",
month = "{JUN}",
abstract = "{We describe the design of a novel type of storage device currently under construction at Stockholm University, Sweden, using purely electrostatic focussing and deflection elements, in which ion beams of opposite charges are confined under extreme high vacuum cryogenic conditions in separate rings{''} and merged over a common straight section. The construction of this double electrostatic ion ring experiment uniquely allows for studies of interactions between cations and anions at low and well-defined internal temperatures and centre-of-mass collision energies down to about 10 K and 10 meV, respectively. Position sensitive multi-hit detector systems have been extensively tested and proven to work in cryogenic environments and these will be used to measure correlations between reaction products in, for example, electron-transfer processes. The technical advantages of using purely electrostatic ion storage devices over magnetic ones are many, but the most relevant are: electrostatic elements which are more compact and easier to construct; remanent fields, hysteresis, and eddy-currents, which are of concern in magnetic devices, are no longer relevant; and electrical fields required to control the orbit of the ions are not only much easier to create and control than the corresponding magnetic fields, they also set no upper mass limit on the ions that can be stored. These technical differences are a boon to new areas of fundamental experimental research, not only in atomic and molecular physics but also in the boundaries of these fields with chemistry and biology. For examples, studies of interactions with internally cold molecular ions will be particular useful for applications in astrophysics, while studies of solvated ionic clusters will be of relevance to aeronomy and biology. (C) 2011 American Institute of Physics. {[}doi:10.1063/1.3602928]}",
doi = "{10.1063/1.3602928}",
article-number = "{065112}",
issn = "{0034-6748}",
researcherid-numbers = "{Misra, Deepankar/C-8813-2009}",
unique-id = "{ISI:000292334000069}"
}

32. A Lawicki, A I S Holm, P Rousseau, M Capron, R Maisonny, S Maclot, F Seitz, H A B Johansson, S Rosen, H T Schmidt, H Zettergren, B Manil, L Adoui, H Cederquist and B A Huber.
Multiple ionization and fragmentation of isolated pyrene and coronene molecules in collision with ions. PHYSICAL REVIEW A 83(2), 2011.
DOI BibTeX

@article{ ISI:000287076800006,
author = "Lawicki, A. and Holm, A. I. S. and Rousseau, P. and Capron, M. and Maisonny, R. and Maclot, S. and Seitz, F. and Johansson, H. A. B. and Rosen, S. and Schmidt, H. T. and Zettergren, H. and Manil, B. and Adoui, L. and Cederquist, H. and Huber, B. A.",
title = "{Multiple ionization and fragmentation of isolated pyrene and coronene molecules in collision with ions}",
journal = "{PHYSICAL REVIEW A}",
year = "{2011}",
volume = "{83}",
number = "{2}",
month = "{FEB 8}",
abstract = "{The interaction of multiply charged ions (He(2+), O(3+), and Xe(20+)) with gas-phase pericondensed polycyclic aromatic hydrocarbon (PAH) molecules of coronene (C(24)H(12)) and pyrene (C(16)H(10)) is studied for low-velocity collisions (v <= 0.6 a.u.). The mass spectrometric analysis shows that singly and up to quadruply charged intact molecules are important reaction products. The relative experimental yields are compared with the results of a simple classical over-the-barrier model. For higher molecular charge states, the experimental yields decrease much more strongly than the model predictions due to the instabilities of the multiply charged PAH molecules. Even-odd oscillations with the number of carbon atoms, n, in the intensity distributions of the C(n)H(x)(+) fragments indicate a linear chain structure of the fragments similar to those observed for ion-C(60) collisions. The latter oscillations are known to be due to dissociation energy differences between even-and odd-n C(n)-chain molecules. For PAH molecules, the average numbers of H atoms attached to the C(n)H(x) chains are larger for even-n reflecting acetylenic bond systems.}",
doi = "{10.1103/PhysRevA.83.022704}",
article-number = "{022704}",
issn = "{1050-2947}",
unique-id = "{ISI:000287076800006}"
}

33. N Haag, A I S Holm, H A B Johansson, H Zettergren, H T Schmidt, Brondsted S Nielsen, P Hvelplund and H Cederquist.
Electron capture induced dissociation of doubly protonated pentapeptides: Dependence on molecular structure and charge separation. JOURNAL OF CHEMICAL PHYSICS 134(3), 2011.
DOI BibTeX

@article{ ISI:000286472200071,
author = "Haag, N. and Holm, A. I. S. and Johansson, H. A. B. and Zettergren, H. and Schmidt, H. T. and Nielsen, S. Brondsted and Hvelplund, P. and Cederquist, H.",
title = "{Electron capture induced dissociation of doubly protonated pentapeptides: Dependence on molecular structure and charge separation}",
journal = "{JOURNAL OF CHEMICAL PHYSICS}",
year = "{2011}",
volume = "{134}",
number = "{3}",
month = "{JAN 21}",
abstract = "{We have studied electron capture induced dissociation of a set of doubly protonated pentapeptides, all composed of one lysine (K) and either four glycine (G) or four alanine (A) residues, as a function of the sequence of these building blocks. Thereby the separation of the two charges, sequestered on the N-terminal amino group and the lysine side chain, is varied. The characteristic cleavage of N-C(alpha) bonds is observed for all peptides over the whole backbone length, with the charge carrying fragments always containing K. The resulting fragmentation patterns are very similar if G is replaced by A. In the case of {[}XKXXX+2H](2+) (X=A or G), a distinct feature is observed in the distribution of backbone cleavage fragments and the probability for ammonia loss is drastically reduced. This may be due to an isomer with an amide oxygen as protonation site giving rise to the observed increase in breakage at a specific site in the molecule. For the other peptides, a correlation with the distance between amide oxygen and the charge at the lysine side chain has been found. This may be an indication that it is only the contribution from this site to the charge stabilization of the amide pi{*} orbitals which determines relative fragment intensities. For comparison, complexes with two crown ether molecules have been studied as well. The crown ether provides a shielding of the charge and prevents the peptide from folding and internal hydrogen bonding, which leads to a more uniform fragmentation behavior. (C) 2011 American Institute of Physics. {[}doi:10.1063/1.3533952]}",
doi = "{10.1063/1.3533952}",
article-number = "{035102}",
issn = "{0021-9606}",
unique-id = "{ISI:000286472200071}"
}

34. A I S Holm, H Zettergren, H A B Johansson, F Seitz, S Rosen, H T Schmidt, A Lawicki, J Rangama, P Rousseau, M Capron, R Maisonny, L Adoui, A Mery, B Manil, B A Huber and H Cederquist.
Ions Colliding with Cold Polycyclic Aromatic Hydrocarbon Clusters. PHYSICAL REVIEW LETTERS 105(21), 2010.
DOI BibTeX

@article{ ISI:000284407400012,
author = "Holm, A. I. S. and Zettergren, H. and Johansson, H. A. B. and Seitz, F. and Rosen, S. and Schmidt, H. T. and Lawicki, A. and Rangama, J. and Rousseau, P. and Capron, M. and Maisonny, R. and Adoui, L. and Mery, A. and Manil, B. and Huber, B. A. and Cederquist, H.",
title = "{Ions Colliding with Cold Polycyclic Aromatic Hydrocarbon Clusters}",
journal = "{PHYSICAL REVIEW LETTERS}",
year = "{2010}",
volume = "{105}",
number = "{21}",
month = "{NOV 19}",
abstract = "{We report the first experimental study of ions interacting with clusters of polycyclic aromatic hydrocarbon (PAH) molecules. Collisions between 11.25 keV He-3(+) or 360 keV Xe-129(20+) and weakly bound clusters of one of the smallest PAH molecules, anthracene, show that C14H10 clusters have much higher tendencies to fragment in ion collisions than other weakly bound clusters. The ionization is dominated by peripheral collisions in which the clusters, very surprisingly, are more strongly heated by Xe20+ collisions than by He+ collisions. The appearance size is k = 15 for {[}C14H10](k)(2+).}",
doi = "{10.1103/PhysRevLett.105.213401}",
article-number = "{213401}",
issn = "{0031-9007}",
unique-id = "{ISI:000284407400012}"
}

35. M Gudmundsson, D Fischer, N Haag, H A B Johansson, D Misra, P Reinhed, H Schmidt-Boecking, R Schuch, M Schoeffler, K Stochkel, H T Schmidt and H Cederquist.
Angular scattering in fast ion-atom electron transfer collisions: projectile wave diffraction and Thomas mechanisms. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS 43(18, SI), 2010.
DOI BibTeX

@article{ ISI:000281530700013,
author = "Gudmundsson, M. and Fischer, D. and Haag, N. and Johansson, H. A. B. and Misra, D. and Reinhed, P. and Schmidt-Boecking, H. and Schuch, R. and Schoeffler, M. and Stochkel, K. and Schmidt, H. T. and Cederquist, H.",
title = "{Angular scattering in fast ion-atom electron transfer collisions: projectile wave diffraction and Thomas mechanisms}",
journal = "{JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS}",
year = "{2010}",
volume = "{43}",
number = "{18, SI}",
month = "{SEP 28}",
abstract = "{We report experimental angular differential cross sections for double-electron capture in He(2+) + He collisions and single-electron capture in H(+) + He collisions for the 1.3-12.5 MeV kinetic energy range. In all cases, the total cross sections are dominated by forward scattering peaks in d sigma/d Omega. The shapes and widths (but not the magnitudes) of these peaks are very similar for all energies and for capture of one or two electrons corresponding also to our measured linear increases in the transverse momentum transfers with increasing projectile velocities. These observations may be ascribed to diffraction limitations which are connected to electron transfer probabilities P(b) which are significant in limited regions of b only. For the H(+) + He single-electron capture we observe two additional maxima in the angular differential cross sections. We conclude that while the secondary maxima at similar to 0.5 mrad probably have large contributions from the Thomas proton-electron-nucleus scattering mechanism, the third maxima at similar to 0.75 mrad are most likely mainly due to projectile de Broglie wave diffraction.}",
doi = "{10.1088/0953-4075/43/18/185209}",
article-number = "{185209}",
issn = "{0953-4075}",
researcherid-numbers = "{Misra, Deepankar/C-8813-2009}",
unique-id = "{ISI:000281530700013}"
}

36. H Zettergren, H A B Johansson, H T Schmidt, J Jensen, P Hvelplund, S Tomita, Y Wang, F Martin, M Alcami, B Manil, L Maunoury, B A Huber and H Cederquist.
Magic and hot giant fullerenes formed inside ion irradiated weakly bound C-60 clusters. JOURNAL OF CHEMICAL PHYSICS 133(10), 2010.
DOI BibTeX

@article{ ISI:000282475400015,
author = "Zettergren, H. and Johansson, H. A. B. and Schmidt, H. T. and Jensen, J. and Hvelplund, P. and Tomita, S. and Wang, Y. and Martin, F. and Alcami, M. and Manil, B. and Maunoury, L. and Huber, B. A. and Cederquist, H.",
title = "{Magic and hot giant fullerenes formed inside ion irradiated weakly bound C-60 clusters}",
journal = "{JOURNAL OF CHEMICAL PHYSICS}",
year = "{2010}",
volume = "{133}",
number = "{10}",
month = "{SEP 14}",
abstract = "{We find that the most stable fullerene isomers, C-70-C-94, form efficiently in close-to central collisions between keV atomic ions and weakly bound clusters of more than 15 C-60-molecules. We observe extraordinarily high yields of C-70 and marked preferences for C-78 and C-84. Larger even-size carbon molecules, C-96-C-180, follow a smooth log-normal (statistical) intensity distribution. Measurements of kinetic energies indicate that C-70-C-94 mainly are formed by coalescence reactions between small carbon molecules and Coo, while C-n with n >= 96 are due to self-assembly (of small molecules) and shrinking hot giant fullerenes. (C) 2010 American Institute of Physics. {[}doi:10.1063/1.3479584]}",
doi = "{10.1063/1.3479584}",
article-number = "{104301}",
issn = "{0021-9606}",
researcherid-numbers = "{Alcami, Manuel/F-1366-2010}",
orcid-numbers = "{Alcami, Manuel/0000-0002-3753-5215}",
unique-id = "{ISI:000282475400015}"
}

37. P Reinhed, A Orban, S Rosen, R D Thomas, I Kashperka, H A B Johansson, D Misra, A Fardi, L Brannholm, M Bjorkhage, H Cederquist and H T Schmidt.
Cryogenic keV ion-beam storage in ConeTrap-A tool for ion-temperature control. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 621(1-3):83-90, September 2010.
DOI BibTeX

@article{ ISI:000281109100011,
author = "Reinhed, P. and Orban, A. and Rosen, S. and Thomas, R. D. and Kashperka, I. and Johansson, H. A. B. and Misra, D. and Fardi, A. and Brannholm, L. and Bjorkhage, M. and Cederquist, H. and Schmidt, H. T.",
title = "{Cryogenic keV ion-beam storage in ConeTrap-A tool for ion-temperature control}",
journal = "{NUCLEAR INSTRUMENTS \& METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT}",
year = "{2010}",
volume = "{621}",
number = "{1-3}",
pages = "{83-90}",
month = "{SEP}",
abstract = "{We have tested the ion-storage capabilities of the compact triple-electrode electrostatic ion-beam trap, ConeTrap, down to cryogenic temperatures. The low-temperature operation of this electrostatic storage device is an important test for the double electrostatic ion-ring experiment, DESIREE, which is presently under construction at Stockholm University. In the present work we measured the pressure dependent storage lifetimes of 2.5 keV He(+) and 2.8 keV Ar(+) ion beams in ConeTrap at temperatures down to 28 K and pressures down to 1.3 x 10(-10) mbar. The so far longest measured ion storage lifetime using this system is 21.5 +/- 3.8 s for Ar(+) ions. The present combination of ConeTrap and the cryogenic experimental chamber was recently applied in the first black-body-correction free measurement of the lifetime of the metastable He(-) ion at 10 K {[}1]. (C) 2010 Elsevier B.V. All rights reserved.}",
doi = "{10.1016/j.nima.2010.06.008}",
issn = "{0168-9002}",
researcherid-numbers = "{Misra, Deepankar/C-8813-2009}",
unique-id = "{ISI:000281109100011}"
}

38. D Fischer, M Gudmundsson, Z Berenyi, N Haag, H A B Johansson, D Misra, P Reinhed, A Kallberg, A Simonsson, K Stochkel, H Cederquist and H T Schmidt.
Importance of Thomas single-electron transfer in fast p-He collisions. PHYSICAL REVIEW A 81(1), January 2010.
DOI BibTeX

@article{ ISI:000277958100023,
author = "Fischer, D. and Gudmundsson, M. and Berenyi, Z. and Haag, N. and Johansson, H. A. B. and Misra, D. and Reinhed, P. and Kallberg, A. and Simonsson, A. and Stochkel, K. and Cederquist, H. and Schmidt, H. T.",
title = "{Importance of Thomas single-electron transfer in fast p-He collisions}",
journal = "{PHYSICAL REVIEW A}",
year = "{2010}",
volume = "{81}",
number = "{1}",
month = "{JAN}",
abstract = "{We report experimental angular differential cross sections for nonradiative single-electron capture in p-He collisions (p + He -> H + He(+)) with a separate peak at the 0.47 mrad Thomas scattering angle for energies in the 1.3-12.5 MeV range. We find that the intensity of this peak scales with the projectile velocity as v(P)(-11). This constitutes the first experimental test of the prediction from 1927 by L. H. Thomas {[}Proc. R. Soc. 114, 561 (1927)]. At our highest energy, the peak at the Thomas angle contributes with 13.5\% to the total integrated nonradiative single-electron capture cross section.}",
doi = "{10.1103/PhysRevA.81.012714}",
article-number = "{012714}",
issn = "{1050-2947}",
researcherid-numbers = "{Misra, Deepankar/C-8813-2009}",
unique-id = "{ISI:000277958100023}"
}

39. P Reinhed, A Orban, J Werner, S Rosen, R D Thomas, I Kashperka, H A B Johansson, D Misra, L Brannholm, M Bjorkhage, H Cederquist and H T Schmidt.
Precision Lifetime Measurements of He- in a Cryogenic Electrostatic Ion-Beam Trap. PHYSICAL REVIEW LETTERS 103(21), 2009.
DOI BibTeX

@article{ ISI:000272054300014,
author = "Reinhed, P. and Orban, A. and Werner, J. and Rosen, S. and Thomas, R. D. and Kashperka, I. and Johansson, H. A. B. and Misra, D. and Brannholm, L. and Bjorkhage, M. and Cederquist, H. and Schmidt, H. T.",
title = "{Precision Lifetime Measurements of He- in a Cryogenic Electrostatic Ion-Beam Trap}",
journal = "{PHYSICAL REVIEW LETTERS}",
year = "{2009}",
volume = "{103}",
number = "{21}",
month = "{NOV 20}",
abstract = "{We have developed a small purely electrostatic ion-beam trap which may be operated in thermal equilibrium at precisely controlled temperatures down to 10 K. Thus, we avoid magnetic field induced mixing of quantum states and may effectively eliminate any influence from absorption of photons from blackbody radiation. We report the first correction-free measurement of the lifetime of the 1s2s2p P-4(5/2)o level of He-4(-) yielding the high-precision result 359.0 +/- 0.7 mu s. This result is an essential proof-of-principle for cryogenic electrostatic storage rings and traps for atomic and molecular physics.}",
doi = "{10.1103/PhysRevLett.103.213002}",
article-number = "{213002}",
issn = "{0031-9007}",
unique-id = "{ISI:000272054300014}"
}

40. Henning Zettergren, Lamri Adoui, Virgile Bernigaud, Henrik Cederquist, Nicole Haag, Anne I S Holm, Bernd A Huber, Preben Hvelplund, Henrik Johansson, Umesh Kadhane, Mikkel Koefoed Larsen, Bo Liu, Bruno Manil, Steen Brondsted Nielsen, Subhasis Panja, Jimmy Rangama, Peter Reinhed, Henning T Schmidt and Kristian Stochkel.
Electron-Capture-Induced Dissociation of Microsolvated Di- and Tripeptide Monocations: Elucidation of Fragmentation Channels from Measurements of Negative Ions. CHEMPHYSCHEM 10(9-10):1619-1623, 2009.
DOI BibTeX

@article{ ISI:000267928100039,
author = "Zettergren, Henning and Adoui, Lamri and Bernigaud, Virgile and Cederquist, Henrik and Haag, Nicole and Holm, Anne I. S. and Huber, Bernd A. and Hvelplund, Preben and Johansson, Henrik and Kadhane, Umesh and Larsen, Mikkel Koefoed and Liu, Bo and Manil, Bruno and Nielsen, Steen Brondsted and Panja, Subhasis and Rangama, Jimmy and Reinhed, Peter and Schmidt, Henning T. and Stochkel, Kristian",
title = "{Electron-Capture-Induced Dissociation of Microsolvated Di- and Tripeptide Monocations: Elucidation of Fragmentation Channels from Measurements of Negative Ions}",
journal = "{CHEMPHYSCHEM}",
year = "{2009}",
volume = "{10}",
number = "{9-10}",
pages = "{1619-1623}",
month = "{JUL 13}",
abstract = "{{The results from an experimental study of bare and microsolvated peptide monocations in high-energy collision with cesium vapor are reported. Neutral radicals form after electron capture from cesium, which decay by H loss, NH, loss or N-C bond cleavage into characteristic z and c fragments. The neutral fragments are converted into negatively charged species in a second collision with cesium and are identified by means of mass spectrometry. For protonated GA (G = glycan",
a = "",
doi = "{10.1002/cphc.200800782}",
issn = "{1439-4235}",
unique-id = "{ISI:000267928100039}"
}

41. Deepankar Misra, H T Schmidt, M Gudmundsson, D Fischer, N Haag, H A B Johansson, A Kallberg, B Najjari, P Reinhed, R Schuch, M Schoeffler, A Simonsson, A B Voitkiv and H Cederquist.
Two-Center Double-Capture Interference in Fast He2++H-2 Collisions. PHYSICAL REVIEW LETTERS 102(15), 2009.
DOI BibTeX

@article{ ISI:000265285700025,
author = "Misra, Deepankar and Schmidt, H. T. and Gudmundsson, M. and Fischer, D. and Haag, N. and Johansson, H. A. B. and Kallberg, A. and Najjari, B. and Reinhed, P. and Schuch, R. and Schoeffler, M. and Simonsson, A. and Voitkiv, A. B. and Cederquist, H.",
title = "{Two-Center Double-Capture Interference in Fast He2++H-2 Collisions}",
journal = "{PHYSICAL REVIEW LETTERS}",
year = "{2009}",
volume = "{102}",
number = "{15}",
month = "{APR 17}",
abstract = "{We report the first observation of Young-type interference effects in a two-electron transfer process. These effects change strongly as the projectile velocity changes in fast (1.2 and 2.0 MeV) He2++H-2 collisions as manifested in strong variations of the double-electron capture rates with the H-2 orientation. This is consistent with fully quantum mechanical calculations, which ignore sequential electron transfer, and a simple projectile de Broglie wave picture assuming that two-electron transfer probabilities are higher in collisions where the projectile passes close to either one of the H-2 nuclei.}",
doi = "{10.1103/PhysRevLett.102.153201}",
article-number = "{153201}",
issn = "{0031-9007}",
researcherid-numbers = "{Misra, Deepankar/C-8813-2009}",
unique-id = "{ISI:000265285700025}"
}

42. Jean Ann Wyer, Henrik Cederquist, Nicote Haag, Bernd A Huber, Preben Hvelplund, Henrik A B Johansson, Remi Maisonny, Steen Brondsted Nielsen, Jimmy Rangama, Patrick Rousseau and Henning T Schmidt.
On the hydrogen loss from protonated nucleobases after electronic excitation or collisional electron capture. EUROPEAN JOURNAL OF MASS SPECTROMETRY 15(6):681-688, 2009.
DOI BibTeX

@article{ ISI:000272826100002,
author = "Wyer, Jean Ann and Cederquist, Henrik and Haag, Nicote and Huber, Bernd A. and Hvelplund, Preben and Johansson, Henrik A. B. and Maisonny, Remi and Nielsen, Steen Brondsted and Rangama, Jimmy and Rousseau, Patrick and Schmidt, Henning T.",
title = "{On the hydrogen loss from protonated nucleobases after electronic excitation or collisional electron capture}",
journal = "{EUROPEAN JOURNAL OF MASS SPECTROMETRY}",
year = "{2009}",
volume = "{15}",
number = "{6}",
pages = "{681-688}",
abstract = "{In this work, we have subjected protonated nucleobases MH(+) (M = guanine, adenine, thymine, uracil and cytosine) to a range of experiments that involve high-energy (50 keV) collision-induced dissociation (CID) and electron capture-induced dissociation. In the tatter case, both neutralisation reionisation and charge reversal were done. For the CID experiments, the ions interacted with O(2). In neutral reionisation, caesium atoms were used as the target gas and the protonated nucleobases captured electrons to give neutrals. These were reionised to cations a microsecond later in collisions with O(2). In choosing Cs as the target gas, we have ensured that the first electron transfer process is favourable (by about 0.1-0.8 eV depending on the base). In the case of protonated adenine, charge reversal experiments (two Cs collisions) were also carried out, with the results corroborating those from the neutralisation-reionisation experiments. We find that white collisional excitation of protonated nucleobases in O(2) may lead to hydrogen loss with limited probabilities, this channel becomes dominant for electron capture events. Indeed, when sampling reionised neutrals on a microsecond timescale, we see that the ratio between MH(+) and M(+) is 0.2-0.4 when one electron is captured from Cs. There are differences in these ratios between the bases but no obvious correlation with recombination energies was found.}",
doi = "{10.1255/ejms.1039}",
issn = "{1469-0667}",
researcherid-numbers = "{Wyer, Jean/B-2455-2010}",
unique-id = "{ISI:000272826100002}"
}

43. Virgile Bernigaud, Henrik Cederquist, Nicole Haag, Anne I S Holm, Bernd A Huber, Preben Hvelplund, Umesh Kadhane, Mikkel Koefoed Larsen, Bruno Manil, Steen Brondsted Nielsen, Subhasis Panja, Sylwia Ptasinska, Jimmy Rangama, Peter Reinhed, Henning T Schmidt, Alexey V Streletskii, Kristian Stochkel, Esben S Worm and Henning Zettergren.
Electron capture-induced dissociation of AK dipeptide dications: Influence of ion velocity, crown-ether complexation and collision gas. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 276(2-3):77-81, 2008.
DOI BibTeX

@article{ ISI:000259846000002,
author = "Bernigaud, Virgile and Cederquist, Henrik and Haag, Nicole and Holm, Anne I. S. and Huber, Bernd A. and Hvelplund, Preben and Kadhane, Umesh and Larsen, Mikkel Koefoed and Manil, Bruno and Nielsen, Steen Brondsted and Panja, Subhasis and Ptasinska, Sylwia and Rangama, Jimmy and Reinhed, Peter and Schmidt, Henning T. and Streletskii, Alexey V. and Stochkel, Kristian and Worm, Esben S. and Zettergren, Henning",
title = "{Electron capture-induced dissociation of AK dipeptide dications: Influence of ion velocity, crown-ether complexation and collision gas}",
journal = "{INTERNATIONAL JOURNAL OF MASS SPECTROMETRY}",
year = "{2008}",
volume = "{276}",
number = "{2-3}",
pages = "{77-81}",
month = "{OCT 1}",
abstract = "{The fragmentation of doubly protonated AK dipeptide ions has been investigated after collisional electron transfer. Electron capture leads to three dominant channels, H loss, NH3 loss, and N-C-alpha bond breakage to give either c(+) or z(+) fragment ions. The relative importance of these channels has been explored as a function of ion velocity, the degree of complexation with crown ether, and collision gas. Our results indicate that H loss and NH3 loss are competing channels whereas the probability of N-C-alpha bond breakage is more or less constant. (C) 2008 Elsevier B.V. All rights reserved.}",
doi = "{10.1016/j.ijms.2008.05.004}",
issn = "{1387-3806}",
unique-id = "{ISI:000259846000002}"
}

44. N Haag, Z Berenyi, P Reinhed, D Fischer, M Gudmundsson, H A B Johansson, H T Schmidt, H Cederquist and H Zettergren.
Kinetic-energy-release distributions and barrier heights for C(2)a+ emission from multiply charged C(60) and C(70) fullerenes. PHYSICAL REVIEW A 78(4), October 2008.
DOI BibTeX

@article{ ISI:000260574100097,
author = "Haag, N. and Berenyi, Z. and Reinhed, P. and Fischer, D. and Gudmundsson, M. and Johansson, H. A. B. and Schmidt, H. T. and Cederquist, H. and Zettergren, H.",
title = "{Kinetic-energy-release distributions and barrier heights for C(2)a+ emission from multiply charged C(60) and C(70) fullerenes}",
journal = "{PHYSICAL REVIEW A}",
year = "{2008}",
volume = "{78}",
number = "{4}",
month = "{OCT}",
doi = "{10.1103/PhysRevA.78.043201}",
article-number = "{043201}",
issn = "{1050-2947}",
unique-id = "{ISI:000260574100097}"
}

45. H T Schmidt, D Fischer, Z Berenyi, C L Cocke, M Gudmundsson, N Haag, H A B Johansson, A Kaellberg, S B Levin, P Reinhed, U Sassenberg, R Schuch, A Simonsson, K Stochkel and H Cederquist.
Evidence of wave-particle duality for single fast hydrogen atoms. PHYSICAL REVIEW LETTERS 101(8), 2008.
DOI BibTeX

@article{ ISI:000258643600021,
author = "Schmidt, H. T. and Fischer, D. and Berenyi, Z. and Cocke, C. L. and Gudmundsson, M. and Haag, N. and Johansson, H. A. B. and Kaellberg, A. and Levin, S. B. and Reinhed, P. and Sassenberg, U. and Schuch, R. and Simonsson, A. and Stochkel, K. and Cederquist, H.",
title = "{Evidence of wave-particle duality for single fast hydrogen atoms}",
journal = "{PHYSICAL REVIEW LETTERS}",
year = "{2008}",
volume = "{101}",
number = "{8}",
month = "{AUG 22}",
abstract = "{We report the direct observation of interference effects in a Young's double-slit experiment where the interfering waves are two spatially separated components of the de Broglie wave of single 1.3 MeV hydrogen atoms formed close to either target nucleus in H(+) + H(2) electron-transfer collisions. Quantum interference strongly influences the results even though the hydrogen atoms have a de Broglie wavelength, lambda(dB), as small as 25 fm.}",
doi = "{10.1103/PhysRevLett.101.083201}",
article-number = "{083201}",
issn = "{0031-9007}",
unique-id = "{ISI:000258643600021}"
}

46. Henning T Schmidt, Henrik A B Johansson, Richard D Thomas, Wolf D Geppert, Nicole Haag, Peter Reinhed, Stefan Rosen, Mats Larsson, Hakan Danared, K -G Rensfelt, Leif Liljeby, Lars Bagge, Mikael Bjorkhage, Mikael Blom, Patrik Lofgren, Anders Kallberg, Ansgar Simonsson, Andras Paal, Henning Zettergren and Henrik Cederquist.
DESIREE as a new tool for interstellar ion chemistry. INTERNATIONAL JOURNAL OF ASTROBIOLOGY 7(3-4):205-208, 2008.
DOI BibTeX

@article{ ISI:000273383100003,
author = "Schmidt, Henning T. and Johansson, Henrik A. B. and Thomas, Richard D. and Geppert, Wolf D. and Haag, Nicole and Reinhed, Peter and Rosen, Stefan and Larsson, Mats and Danared, Hakan and Rensfelt, K. -G. and Liljeby, Leif and Bagge, Lars and Bjorkhage, Mikael and Blom, Mikael and Lofgren, Patrik and Kallberg, Anders and Simonsson, Ansgar and Paal, Andras and Zettergren, Henning and Cederquist, Henrik",
title = "{DESIREE as a new tool for interstellar ion chemistry}",
journal = "{INTERNATIONAL JOURNAL OF ASTROBIOLOGY}",
year = "{2008}",
volume = "{7}",
number = "{3-4}",
pages = "{205-208}",
month = "{JUL-OCT}",
abstract = "{A novel cryogenic electrostatic storage device consisting of two ion-beam storage rings with a common straight section for studies of interactions between oppositely charged ions at low and well-defined relative velocities is under construction at Stockholm University. Here we consider the prospect Of using this new tool to measure cross-sections and rate coefficients for Mutual neutralization reactions of importance in interstellar ion chemistry in general and specifically in cosmic pre-biotic ion chemistry.}",
doi = "{10.1017/S1473550408004229}",
issn = "{1473-5504}",
unique-id = "{ISI:000273383100003}"
}

47. J Bernard, G Montagne, R Bredy, B Terpend-Ordaciere, A Bourgey, M Kerleroux, L Chen, H T Schmidt, H Cederquist and S Martin.
{A “tabletop” electrostatic ion storage ring: Mini-Ring}. REVIEW OF SCIENTIFIC INSTRUMENTS 79(7), July 2008.
DOI BibTeX

@article{ ISI:000258179400053,
author = "Bernard, J. and Montagne, G. and Bredy, R. and Terpend-Ordaciere, B. and Bourgey, A. and Kerleroux, M. and Chen, L. and Schmidt, H. T. and Cederquist, H. and Martin, S.",
title = "{A tabletop{''} electrostatic ion storage ring: Mini-Ring}",
journal = "{REVIEW OF SCIENTIFIC INSTRUMENTS}",
year = "{2008}",
volume = "{79}",
number = "{7}",
month = "{JUL}",
abstract = "{We report on the design, construction, and commissioning of a novel electrostatic ion storage ring of small dimensions-in the following referred to as Mini-Ring.{''} Mini-Ring consists of four horizontal parallel-plate deflectors and two conical electrostatic mirrors. Ions are injected through the two deflectors on the injection side and off axis with respect to the conical mirrors which face each other. The first injection deflector, originally at zero voltage, is switched to its set value such that the ions after one turn follow stable trajectories of lengths of roughly 30 cm. This design reduces the number of electrodes necessary to guide the ion beam through the ring in stable orbits. The six elements (deflectors and mirrors) are placed on a common grounded plate-the tabletop. Here, we present the design, ion trajectory simulations, and results of the first test experiments demonstrating the successful room-temperature operation of Mini-Ring at background pressures of 10(-6)-10(-7) mbar. (c) 2008 American Institute of Physics.}",
doi = "{10.1063/1.2957609}",
article-number = "{075109}",
issn = "{0034-6748}",
unique-id = "{ISI:000258179400053}"
}

48. B Liu, N Haag, H Johansson, H T Schmidt, H Cederquist, Brondsted S Nielsen, H Zettergren, P Hvelplund, B Manil and B A Huber.
Electron capture induced dissociation of nucleotide anions in water nanodroplets. JOURNAL OF CHEMICAL PHYSICS 128(7), 2008.
DOI BibTeX

@article{ ISI:000253336800043,
author = "Liu, B. and Haag, N. and Johansson, H. and Schmidt, H. T. and Cederquist, H. and Nielsen, S. Brondsted and Zettergren, H. and Hvelplund, P. and Manil, B. and Huber, B. A.",
title = "{Electron capture induced dissociation of nucleotide anions in water nanodroplets}",
journal = "{JOURNAL OF CHEMICAL PHYSICS}",
year = "{2008}",
volume = "{128}",
number = "{7}",
month = "{FEB 21}",
abstract = "{We have studied the outcome of collisions between the hydrated nucleotide anion adenosine 5(')-monophosphate (AMP) and sodium. Electron capture leads to hydrogen loss as well as water evaporation regardless of the initial number m of water molecules attached to the parent ion (m <= 16). The yield of dianions with microsecond lifetimes increases strongly with m, which is explained from dielectric screening of the two charges by the water nanodroplet. For comparison, collision induced dissociation results in water losses with no or very little damage of the AMP molecule itself.}",
doi = "{10.1063/1.2839597}",
article-number = "{075102}",
issn = "{0021-9606}",
unique-id = "{ISI:000253336800043}"
}

49. Stefan Rosen, Henning T Schmidt, Peter Reinhed, Daniel Fischer, Richard D Thomas, Henrik Cederquist, Leif Liljeby, Lars Bagge, Sven Leontein and Mikael Blom.
Operating a triple stack microchannel plate-phosphor assembly for single particle counting in the 12-300 K temperature range. REVIEW OF SCIENTIFIC INSTRUMENTS 78(11), November 2007.
DOI BibTeX

@article{ ISI:000251325900012,
author = "Rosen, Stefan and Schmidt, Henning T. and Reinhed, Peter and Fischer, Daniel and Thomas, Richard D. and Cederquist, Henrik and Liljeby, Leif and Bagge, Lars and Leontein, Sven and Blom, Mikael",
title = "{Operating a triple stack microchannel plate-phosphor assembly for single particle counting in the 12-300 K temperature range}",
journal = "{REVIEW OF SCIENTIFIC INSTRUMENTS}",
year = "{2007}",
volume = "{78}",
number = "{11}",
month = "{NOV}",
abstract = "{An assembly consisting of a stack of three microchannel plates (MCPs) and a phosphor screen anode has been operated over the temperature range from 300 to 12 K. We report on measurements at 6.4 kHz (using an alpha source) and with dark counts only (15 Hz). Without any particle source, the MCP bias current decreased by a factor of 2.1x10(3) when the temperature was lowered from 300 to 12 K. Using the alpha source, and a photomultiplier tube (PMT) to monitor the phosphor screen anode, we first observed an increase in the decay time of the phosphor from 12 to 45 mu s when the temperature was decreased from 300 to 100 K while the decay time then decreased and reached a value of 5 mu s at 12 K. The pulse height distribution from the PMT was measured between 300 and 12 K and shows a spectrum typical for a MCP phosphor setup at 300 K and 12 K but is strongly degraded for intermediate temperatures. We conclude that the present MCP-phosphor detector assembly is well suited for position-sensitive particle counting operation at temperatures down to at least 12 K even for count rates beyond 6 kHz. This result is crucial and an important part of ongoing developments of new instrumentation for investigations of, e.g., interactions involving complex molecular ions with internal quantum state control. (C) 2007 American Institute of Physics.}",
doi = "{10.1063/1.2814030}",
article-number = "{113301}",
issn = "{0034-6748}",
unique-id = "{ISI:000251325900012}"
}

50. Henning Zettergren, Henning T Schmidt, Peter Reinhed, Henrik Cederquist, Jens Jensen, Preben Hvelplund, Shigeo Tomita, Bruno Manil, Jimmy Rangama and Bernd A Huber.
Stabilities of multiply charged dimers and clusters of fullerenes. JOURNAL OF CHEMICAL PHYSICS 126(22), 2007.
DOI BibTeX

@article{ ISI:000247247400015,
author = "Zettergren, Henning and Schmidt, Henning T. and Reinhed, Peter and Cederquist, Henrik and Jensen, Jens and Hvelplund, Preben and Tomita, Shigeo and Manil, Bruno and Rangama, Jimmy and Huber, Bernd A.",
title = "{Stabilities of multiply charged dimers and clusters of fullerenes}",
journal = "{JOURNAL OF CHEMICAL PHYSICS}",
year = "{2007}",
volume = "{126}",
number = "{22}",
month = "{JUN 14}",
abstract = "{The authors find even-odd variations as functions of r (<= 7) for multiple ionization of van der Waals dimers in slow Xe(30+)+{[}C(60)](2)({[}C(60)C(70)])->center dot+{[}C(60)](2)(r+)({[}C(60)C(70)](r+)) electron-transfer collisions. This even-odd behavior is in sharp contrast to the smooth one for fullerene monomers and may be related to even-odd effects in dimer ionization energies in agreement with results from an electrostatic model. The kinetic energy releases for dimer dissociations {[}predominantly yielding intact fullerenes {[}C(60)](2)(r+)-> C(60)(r1+)+C(60)(r2+) in the same (r1=r2) or nearby (r1=r2 +/- 1) charge states] are found to be low in comparison with the corresponding model results indicating that internal excitations of the separating (intact) fullerenes are important. Experimental appearance sizes for the heavier clusters of fullerenes {[}C(60)](n)(r+) (n > 3 and r=2-5) compare well with predictions from a new nearest-neighbor model assuming that r unit charges in {[}C(60)](n)(r+) are localized to r C(60) molecules such that the Coulomb energy of the system is minimized. The system is then taken to be stable if (i) two (singly) charged C(60) are not nearest neighbors and (ii) the r C(60)(+) molecules have binding energies to their neutral nearest neighbors which are larger than the repulsive energies for the (r-1) C(60)(+)-C(60)(+) pairs. Essential ingredients in the nearest-neighbor model are cluster geometries and the present results on dimer stabilities. (c) 2007 American Institute of Physics.}",
doi = "{10.1063/1.2743433}",
article-number = "{224303}",
issn = "{0021-9606}",
unique-id = "{ISI:000247247400015}"
}

51. H Zettergren, H T Schmidt, P Reinhed, H Cederquist, J Jensen, P Hvelplund, S Tomita, B Manil, J Rangama and B A Huber.
{Even-odd effects in the ionization cross sections of [C-60](2) and [C60C70] dimers}. PHYSICAL REVIEW A 75(5), May 2007.
DOI BibTeX

@article{ ISI:000246890400009,
author = "Zettergren, H. and Schmidt, H. T. and Reinhed, P. and Cederquist, H. and Jensen, J. and Hvelplund, P. and Tomita, S. and Manil, B. and Rangama, J. and Huber, B. A.",
title = "{Even-odd effects in the ionization cross sections of {[}C-60](2) and {[}C60C70] dimers}",
journal = "{PHYSICAL REVIEW A}",
year = "{2007}",
volume = "{75}",
number = "{5}",
month = "{MAY}",
abstract = "{We report strong even-odd effects in multiple ionization yields of van der Waals dimers in slow Xe30++{[}C-60](2)({[}C60C70])->center dot center dot center dot+{[}C-60](2)(r+)({[}C60C70](r+)) electron-transfer collisions as functions of r <= 7. This behavior may be due to even-odd variations in the sequences of dimer ionization energies as calculated with an electrostatic model including an electrical fullerene-fullerene contact at the 19a(0) center-center separation in {[}C-60](2)(+). Prompt dissociations predominantly yield intact fullerenes {[}C-60](2)(r+)-> C-60(1)r++C-60(2)r+ in the same (r(1)=r(2), even r) or nearby (r(1)=r(2)+/- 1, odd r>1) charge states.}",
doi = "{10.1103/PhysRevA.75.051201}",
article-number = "{051201}",
issn = "{1050-2947}",
unique-id = "{ISI:000246890400009}"
}

52. O Kamalou, B Manil, H Lebius, J Rangama, B A Huber, P Hvelplund, S Tomita, J Jensen, H T Schmidt, H Zettergren and H Cederquist.
Fullerene collisions and clusters of fullerenes. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 252(2):117-125, 2006.
DOI BibTeX

@article{ ISI:000237768900006,
author = "Kamalou, O. and Manil, B. and Lebius, H. and Rangama, J. and Huber, B. A. and Hvelplund, P. and Tomita, S. and Jensen, J. and Schmidt, H. T. and Zettergren, H. and Cederquist, H.",
title = "{Fullerene collisions and clusters of fullerenes}",
journal = "{INTERNATIONAL JOURNAL OF MASS SPECTROMETRY}",
year = "{2006}",
volume = "{252}",
number = "{2}",
pages = "{117-125}",
month = "{MAY 15}",
abstract = "{Electron capture processes were studied in glancing collisions between multiply charged C(60)(q+) ions and neutral C(60) molecules at low collision energies where nuclear stopping dominates the interaction (typical energy: 10 keV; velocity v = 0.024 a.u.). In addition, clusters of fullerenes were multiply ionized in collisions with highly charged slow ions and their fragmentation spectra were measured by applying multi-coincidence techniques in a second, separate experiment. Through the first experiment we show that non-fragmenting electron capture collisions do not produce free electrons in C(60)(q+)-C(60) collisions (q = 1-5), i.e., the cross sections for transfer ionization processes are negligible in this charge state regime. This is in contrast to the case of atomic projectile ions where transfer ionization processes, as e.g., C(q+) + C(60) -> C((q-r)+) + C(60)(r+) -> C((q-r+1)+) + C(60)(r+) +e(-), are strong for q > 2. These results are rationalized by means of the classical over-the-barrier model for electron transfer between two C(60) molecules, or between an atomic ion and a C(60) molecule, where the molecules are modeled as conducting spheres. Further, the same model may also be used as a basis for understanding the present observations of limitations in the maximum numbers of charges, which might be transferred in non-fragmenting C(60)(q+)-C(60) collisions (q/2 for even q and (q + 1)/2 for odd q) and in C(q+)-C(60) collision (here up to q charges may be transferred). In the same experiment, we have further measured scattering angles, theta, and energy losses, epsilon, for the fullerene projectiles in C(60)(q+)-C(60) collisions and we have found low values for both theta and epsilon, which, however, increase with the number of C(2)-units lost from the projectile fullerene in electron capture collisions. The critical distances for electron transfer which are deduced from the C(60)(q+)-C(60) collision experiment and the Zettergren model are then used to explain the high charge mobility between the individual C(60) molecules in charged (C(60))(n) van der Waal's clusters of fullerenes, which we observe in the second experiment. (C) 2006 Elsevier BX All rights reserved.}",
doi = "{10.1016/j.ijms.2005.12.054}",
issn = "{1387-3806}",
unique-id = "{ISI:000237768900006}"
}

53. H Zettergren, P Reinhed, K Stochkel, HT Schmidt, H Cederquist, J Jensen, S Tomita, SB Nielsen, P Hvelplund, B Manil, J Rangama and BA Huber.
Fragmentation and ionization of C-70 and C-60 by slow ions of intermediate charge. EUROPEAN PHYSICAL JOURNAL D 38(2):299-306, May 2006.
DOI BibTeX

@article{ ISI:000236841000009,
author = "Zettergren, H and Reinhed, P and Stochkel, K and Schmidt, HT and Cederquist, H and Jensen, J and Tomita, S and Nielsen, SB and Hvelplund, P and Manil, B and Rangama, J and Huber, BA",
title = "{Fragmentation and ionization of C-70 and C-60 by slow ions of intermediate charge}",
journal = "{EUROPEAN PHYSICAL JOURNAL D}",
year = "{2006}",
volume = "{38}",
number = "{2}",
pages = "{299-306}",
month = "{MAY}",
abstract = "{We have measured total and coincident (with outgoing charge-state analyzed projectiles) ionization and fragmentation spectra of C-60 and C-70 following collisions with Xe4+ and Kr4+ at v = 0.06 a.u. Intact positive fullerene ions in charge states up to five (C-60(5+) and C-70(5+)) are produced with both projectiles and for Kr4++C-70 collisions we even observe a small C-70(6+) peak. The C-60/70-2m(3+) (m=1-7) intensity distributions are predominantly associated with the stabilization of three electrons on the projectile (s=3) and are significantly different for Xe4+- and Kr4+-projectiles. On the other hand, we find remarkable similarities in the C-3(+)-C-11(+) multi-fragmentation pattern regardless of projectile species (mass) although they are associated with closer encounters in which the projectile is fully neutralized (s=4). Simple Monte Carlo calculations of nuclear and electronic loss processes show that both these contributions are very similar in glancing Xe4++C-60 and Kr4++C-60 collisions, suggesting that frontal (and more violent) collisions are strongly suppressed under the present experimental conditions. Nevertheless it is surprising that the more distant collisions (s=3) are projectile mass dependent, while the closer collisions (s=4) are not. This indicates that this simple approach (although it reproduces more advanced quantum mechanical calculations for slow collisions with singly charged atomic ions rather well) is not valid for a comprehensive description of the energy transfer processes in the present collision systems involving projectiles of higher charge states.}",
doi = "{10.1140/epjd/e2006-00005-7}",
issn = "{1434-6060}",
unique-id = "{ISI:000236841000009}"
}

54. D Fischer, K Stochkel, H Cederquist, H Zettergren, P Reinhed, R Schuch, A Kallberg, A Simonsson and H T Schmidt.
Experimental separation of the Thomas charge-transfer process in high-velocity p-He collisions. PHYSICAL REVIEW A 73(5), May 2006.
DOI BibTeX

@article{ ISI:000237949300078,
author = "Fischer, D. and Stochkel, K. and Cederquist, H. and Zettergren, H. and Reinhed, P. and Schuch, R. and Kallberg, A. and Simonsson, A. and Schmidt, H. T.",
title = "{Experimental separation of the Thomas charge-transfer process in high-velocity p-He collisions}",
journal = "{PHYSICAL REVIEW A}",
year = "{2006}",
volume = "{73}",
number = "{5}",
month = "{MAY}",
abstract = "{We present differential cross sections of electron capture in 7.5 MeV and 12.5 MeV proton-helium collisions. Complete experimental separations of the Thomas and the kinematic single electron capture processes in the two-dimensional He+ momentum distribution in the plane perpendicular to the fast ion beam have been achieved. We compare the resulting projectile angular differential cross section with the two most recent theoretical calculations and expose significant deviations.}",
doi = "{10.1103/PhysRevA.73.052713}",
article-number = "{052713}",
issn = "{1050-2947}",
unique-id = "{ISI:000237949300078}"
}

55. S Tomita, JU Andersen, H Cederquist, B Concina, O Echt, JS Forster, K Hansen, BA Huber, P Hvelplund, J Jensen, B Liu, B Manil, L Maunoury, SB Nielsen, J Rangama, HT Schmidt and H Zettergren.
Lifetimes of C-60(2-) and C-70(2-) dianions in a storage ring. JOURNAL OF CHEMICAL PHYSICS 124(2), 2006.
DOI BibTeX

@article{ ISI:000234607700027,
author = "Tomita, S and Andersen, JU and Cederquist, H and Concina, B and Echt, O and Forster, JS and Hansen, K and Huber, BA and Hvelplund, P and Jensen, J and Liu, B and Manil, B and Maunoury, L and Nielsen, SB and Rangama, J and Schmidt, HT and Zettergren, H",
title = "{Lifetimes of C-60(2-) and C-70(2-) dianions in a storage ring}",
journal = "{JOURNAL OF CHEMICAL PHYSICS}",
year = "{2006}",
volume = "{124}",
number = "{2}",
month = "{JAN 14}",
abstract = "{C-60(2-) and C-70(2-) dianions have been produced by electrospray of the monoanions and subsequent electron pickup in a Na vapor cell. The dianions were stored in an electrostatic ring and their decay by electron emission was measured up to 1 s after injection. While C-70(2-) ions are stable on this time scale, except for a small fraction of the ions which have been excited by gas collisions, most of the C-60(2-) ions decay on a millisecond time scale, with a lifetime depending strongly on their internal temperature. The results can be modeled as decay by electron tunneling through a Coulomb barrier, mainly from thermally populated triplet states about 120 meV above a singlet ground state. At times longer than about 100 ms, the absorption of blackbody radiation plays an important role for the decay of initially cold ions. The tunneling rates obtained from the modeling, combined with WKB estimates of the barrier penetration, give a ground-state energy 200 +/- 30 meV above the energy of the monoanion plus a free electron and a ground-state lifetime of the order of 20 s. (c) 2006 American Institute of Physics.}",
doi = "{10.1063/1.2155435}",
article-number = "{024310}",
issn = "{0021-9606}",
researcherid-numbers = "{Hansen, Klavs/J-1959-2012}",
unique-id = "{ISI:000234607700027}"
}

56. K Stochkel, O Eidem, H Cederquist, H Zettergren, P Reinhed, R Schuch, CL Cocke, SB Levin, VN Ostrovsky, A Kalberg, A Simonsson, J Jensen and HT Schmidt.
Two-center interference in fast proton-H-2-electron transfer and excitation processes. PHYSICAL REVIEW A 72(5), November 2005.
DOI BibTeX

@article{ ISI:000233603400010,
author = "Stochkel, K and Eidem, O and Cederquist, H and Zettergren, H and Reinhed, P and Schuch, R and Cocke, CL and Levin, SB and Ostrovsky, VN and Kalberg, A and Simonsson, A and Jensen, J and Schmidt, HT",
title = "{Two-center interference in fast proton-H-2-electron transfer and excitation processes}",
journal = "{PHYSICAL REVIEW A}",
year = "{2005}",
volume = "{72}",
number = "{5}",
month = "{NOV}",
abstract = "{We present experimental evidence for a strong dependence on the angle between the molecular axis of H-2 and the direction of the incoming projectile (p) in the cross section for transfer excitation in fast p-H-2 collisions. For collision energies of 1.0 and 1.3 MeV we find good agreement between the observed data and an analytical expression based on a two-atomic-center description using Brinkman-Kramers amplitudes. This clearly shows that the observed angular dependence is a result of quantum mechanical interference and not a trivial geometrical effect.}",
doi = "{10.1103/PhysRevA.72.050703}",
article-number = "{050703}",
issn = "{1050-2947}",
unique-id = "{ISI:000233603400010}"
}

57. B Manil, L Maunoury, J Jensen, H Cederquist, HT Schmidt, H Zettergren, P Hvelplund, S Tomita and BA Huber.
Fragmentation of charged fullerene dimers: Kinetic energy release. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 235:419-424, July 2005.
DOI BibTeX

@article{ ISI:000230334400084,
author = "Manil, B and Maunoury, L and Jensen, J and Cederquist, H and Schmidt, HT and Zettergren, H and Hvelplund, P and Tomita, S and Huber, BA",
title = "{Fragmentation of charged fullerene dimers: Kinetic energy release}",
journal = "{NUCLEAR INSTRUMENTS \& METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS}",
year = "{2005}",
volume = "{235}",
pages = "{419-424}",
month = "{JUL}",
note = "{12th International Conference on the Physics of Highly Charged Ions, Vilnius, LITHUANIA, SEP 06-11, 2004}",
abstract = "{We have performed an experimental study of highly charged clusters of fullerenes produced in slow collisions with highly charged ions. Collision products are analysed with respect to their mass to charge ratio and their initial kinectic energy by a linear time-of-flight mass spectrometer. An event-by-event data registration mode allows to study the correlation between the different detected fragments. In this paper, we focus on the kinetic energy releases (KER) in the fragmentation of charged dimers of fullerenes. The results are compared with theoretical values obtained from the conducting sphere model. (c) 2005 Elsevier B.V. All rights reserved.}",
doi = "{10.1016/j.nimb.2005.03.217}",
issn = "{0168-583X}",
unique-id = "{ISI:000230334400084}"
}

58. HT Schmidt, J Jensen, P Reinhed, R Schuch, K Stochkel, H Zettergren, H Cederquist, L Bagge, H Danared, A Kallberg, H Schmidt-Bocking and CL Cocke.
Recoil-ion momentum distributions for transfer ionization in fast proton-He collisions. PHYSICAL REVIEW A 72(1), July 2005.
DOI BibTeX

@article{ ISI:000230887300093,
author = "Schmidt, HT and Jensen, J and Reinhed, P and Schuch, R and Stochkel, K and Zettergren, H and Cederquist, H and Bagge, L and Danared, H and Kallberg, A and Schmidt-Bocking, H and Cocke, CL",
title = "{Recoil-ion momentum distributions for transfer ionization in fast proton-He collisions}",
journal = "{PHYSICAL REVIEW A}",
year = "{2005}",
volume = "{72}",
number = "{1}",
month = "{JUL}",
abstract = "{We present high-luminosity experimental investigations of the transfer ionization (TI:p+He -> H-0+He2++e(-)) process in collisions between fast protons and neutral helium atoms in the earlier inaccessibly high-energy range 1.4-5.8 MeV. The protons were stored in the heavy-ion storage and cooler ring CRYRING, where they intersected a narrow supersonic helium gas jet. We discuss the longitudinal recoil-ion momentum distribution, as measured by means of cold-target recoil-ion momentum spectroscopy and find that this distribution splits into two completely separated peaks at the high end of our energy range. These separate contributions are discussed in terms of the earlier proposed Thomas TI (TTI) and kinematic TI mechansims. The cross section of the TTI process is found to follow a sigma proportional to v(-b) dependence with b=10.78 +/- 0.27 in accordance with the expected v(-11) asymptotic behavior. Further, we discuss the probability for shake-off accompanying electron transfer and the relation of this TI mechanism to photodouble ionization. Finally the influence of the initial-state electron velocity distribution on the TTI process is discussed.}",
doi = "{10.1103/PhysRevA.72.012713}",
article-number = "{012713}",
issn = "{1050-2947}",
unique-id = "{ISI:000230887300093}"
}

59. H Schmidt-Bocking, MS Schoffler, T Jahnke, A Czasch, V Mergel, L Schmidt, R Dorner, O Jagutzki, M Hattass, T Weber, E Weigold, HT Schmidt, R Schuch, H Cederquist, Y Demkov, C Whelan, A Godunov and J Walters.
Many-particle fragmentation processes in atomic and molecular physics - new insight into the world of correlation. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 233:3-11, May 2005.
DOI BibTeX

@article{ ISI:000230063600003,
author = "Schmidt-Bocking, H and Schoffler, MS and Jahnke, T and Czasch, A and Mergel, V and Schmidt, L and Dorner, R and Jagutzki, O and Hattass, M and Weber, T and Weigold, E and Schmidt, HT and Schuch, R and Cederquist, H and Demkov, Y and Whelan, C and Godunov, A and Walters, J",
title = "{Many-particle fragmentation processes in atomic and molecular physics - new insight into the world of correlation}",
journal = "{NUCLEAR INSTRUMENTS \& METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS}",
year = "{2005}",
volume = "{233}",
pages = "{3-11}",
month = "{MAY}",
note = "{8th Workshop on Fast Ion-Atom Collisions, Debrecen, HUNGARY, SEP 01-03, 2004}",
abstract = "{Correlated many-particle dynamics in Coulombic systems, which is one of the unsolved fundamental problems in AMO-physics, can now be experimentally approached with so far unprecedented completeness and precision. The recent development of the COLTRIMS technique (COLd Target Recoil Ion Momentum Spectroscopy) provides a coincident multi-fragment imaging technique for eV and sub-eV fragment detection. In its completeness it is as powerful as the bubble chamber in high energy physics. In recent benchmark experiments quasi snapshots (duration as short as an attosecond) of the correlated dynamics between electrons and nuclei have been made for atomic and molecular objects. This new imaging technique has opened a powerful observation window into the hidden world of many-particle dynamics. (c) 2005 Published by Elsevier B.V.}",
doi = "{10.1016/j.nimb.2005.03.079}",
issn = "{0168-583X}",
researcherid-numbers = "{Schoeffler, Markus/B-6261-2008 Godunov, Alexander/G-4266-2011 Doerner, Reinhard/A-5340-2008}",
orcid-numbers = "{Doerner, Reinhard/0000-0002-3728-4268}",
unique-id = "{ISI:000230063600003}"
}

60. HT Schmidt, A Fardi, J Jensen, P Reinhed, R Schuch, K Stochkel, H Zettergren, H Cederquist and CL Cocke.
Transfer ionization in p+He collisions. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 233:43-47, May 2005.
DOI BibTeX

@article{ ISI:000230063600008,
author = "Schmidt, HT and Fardi, A and Jensen, J and Reinhed, P and Schuch, R and Stochkel, K and Zettergren, H and Cederquist, H and Cocke, CL",
title = "{Transfer ionization in p+He collisions}",
journal = "{NUCLEAR INSTRUMENTS \& METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS}",
year = "{2005}",
volume = "{233}",
pages = "{43-47}",
month = "{MAY}",
note = "{8th Workshop on Fast Ion-Atom Collisions, Debrecen, HUNGARY, SEP 01-03, 2004}",
abstract = "{Using the unique combination of the high-quality ion beams available in the heavy-ion storage ring CRYRING at the Manne Siegbahn Laboratory, Stockholm and our COLTRIMS (cold target recoil-ion-momentum spectroscopy) setup with a pulsed extraction system we have investigated the recoil-ion-momentum distributions for transfer ionization in p-He collisions at energies up to 5.8 MeV. This technique allows us to determine the separate contribution to the cross section from the Thomas p-e-e scattering mechanism. Unlike the situation at lower collision energies we find that the cross section follows the expected asymptotic v(-11) scaling. (c) 2005 Published by Elsevier B.V.}",
doi = "{10.1016/j.nimb.2005.03.084}",
issn = "{0168-583X}",
unique-id = "{ISI:000230063600008}"
}

61. L Maunoury, B Manil, J Rangama, H Lebius, BA Huber, JY Pacquet, R Leroy, UV Pedersen, P Hvelplund, J Jensen, S Tomita, H Zettergren, HT Schmidt, H Cederquist and F Gustavo.
Ion beams of carbon clusters and multiply charged fullerenes produced with electron cyclotron resonance ion sources. REVIEW OF SCIENTIFIC INSTRUMENTS 76(5), May 2005.
DOI BibTeX

@article{ ISI:000229064300015,
author = "Maunoury, L and Manil, B and Rangama, J and Lebius, H and Huber, BA and Pacquet, JY and Leroy, R and Pedersen, UV and Hvelplund, P and Jensen, J and Tomita, S and Zettergren, H and Schmidt, HT and Cederquist, H and Gustavo, F",
title = "{Ion beams of carbon clusters and multiply charged fullerenes produced with electron cyclotron resonance ion sources}",
journal = "{REVIEW OF SCIENTIFIC INSTRUMENTS}",
year = "{2005}",
volume = "{76}",
number = "{5}",
month = "{MAY}",
abstract = "{The production of carbon cluster ions by injecting C-60 fullerene vapor into different electron cyclotron resonance (ECR) ion sources (MONO1001/2.45 GHz and CAPRICE/14 GHz) is described. The extracted ion mass spectra show a bimodal distribution, well known from collisions between electrons or ions and fullerenes. In addition to small carbon clusters and even-numbered fullerene ions, odd-numbered clusters with (n > 30) are detected with low intensities. In particular, we have analyzed the mass spectra as a function of the rf power applied to the ECR plasma. Optimum power values are found for the production of individual carbon cluster ions, which increase with decreasing cluster size. Whereas at low power the production of fullerene ions dominates, the intensity of the very small carbon clusters is found to strongly increase with the injected power. This difference in the power dependence is used to vary and to determine the beam composition for ions with identical mass/charge ratios. (c) 2005 American Institute of Physics.}",
doi = "{10.1063/1.1900663}",
article-number = "{053304}",
issn = "{0034-6748}",
unique-id = "{ISI:000229064300015}"
}

62. JU Andersen, H Cederquist, JS Forster, BA Huber, P Hvelplund, J Jensen, B Liu, B Manil, L Maunoury, SB Nielsen, UV Pedersen, J Rangama, HT Schmidt, S Tomita and H Zettergren.
Photodissociation of protonated amino acids and peptides in an ion storage ring. Determination of Arrhenius parameters in the high-temperature limit. PHYSICAL CHEMISTRY CHEMICAL PHYSICS 6(10):2676-2681, 2004.
DOI BibTeX

@article{ ISI:000222182100018,
author = "Andersen, JU and Cederquist, H and Forster, JS and Huber, BA and Hvelplund, P and Jensen, J and Liu, B and Manil, B and Maunoury, L and Nielsen, SB and Pedersen, UV and Rangama, J and Schmidt, HT and Tomita, S and Zettergren, H",
title = "{Photodissociation of protonated amino acids and peptides in an ion storage ring. Determination of Arrhenius parameters in the high-temperature limit}",
journal = "{PHYSICAL CHEMISTRY CHEMICAL PHYSICS}",
year = "{2004}",
volume = "{6}",
number = "{10}",
pages = "{2676-2681}",
month = "{MAY 21}",
abstract = "{We have measured the time dependence of the fragmentation of protonated amino acids and peptides upon UV excitation in an electrostatic ion storage ring. After absorption of a 266 nm photon, protonated Trp (TrpH(+)) has a lifetime of 10-20 mus but also a component with a millisecond lifetime is present. The long lifetime may be due to fluorescence, which leads to ions with lower excitation energy, or to the decay of the Trp(+.) radical cation formed after prompt hydrogen loss in the laser interaction region. Only one component with a lifetime of about 10 mus was detected for TyrH(+). The lifetime of photoexcited PheH(+) is even shorter with an upper limit of a few microseconds. For the singly protonated tripeptides (LysTrpLysH(+) and LysTyrLysH(+)), the decay curves are found to consist of a single component that can be reproduced with an assumption of statistical decay after equilibration of the photon energy among all vibrational modes. The rate constant is expressed in the Arrhenius form in terms of the microcanonical temperature, and the decay rate is obtained by integration over the energy distribution, which has a spread corresponding to the canonical energy distribution at room temperature. The resulting deviation from exponential decay makes it possible to determine the decay parameters from a measurement at a single photon wavelength. Activation energies of E(a), 1.24 +/- 0.07 and 1.5 +/- 0.4 eV were determined for LysTrpLysH(+) and LysTyrLysH(+), respectively, with pre-exponential factors of A(d) = 10(11.1+/-0.5) and 10(12.9+/-2.6) s(-1).}",
doi = "{10.1039/b316845j}",
issn = "{1463-9076}",
unique-id = "{ISI:000222182100018}"
}

63. J Jensen, H Zettergren, HT Schmidt, H Cederquist, S Tomita, SB Nielsen, J Rangama, P Hvelplund, B Manil and BA Huber.
Ionization of C-70 and C-60 molecules by slow highly charged ions: A comparison. PHYSICAL REVIEW A 69(5), May 2004.
DOI BibTeX

@article{ ISI:000221813700102,
author = "Jensen, J and Zettergren, H and Schmidt, HT and Cederquist, H and Tomita, S and Nielsen, SB and Rangama, J and Hvelplund, P and Manil, B and Huber, BA",
title = "{Ionization of C-70 and C-60 molecules by slow highly charged ions: A comparison}",
journal = "{PHYSICAL REVIEW A}",
year = "{2004}",
volume = "{69}",
number = "{5}",
month = "{MAY}",
abstract = "{We have studied collisions between slow highly charged ions and pure C-70 and C-60 molecular targets, and report on measurements of target ionization and fragmentation in electron transfer processes. The intensity distributions in the fragmentation spectra for C-60 and C-70 are rather similar, indicating that similar roles are played by evaporation (neutral C-2 emission) and fission processes (charged particle emission) in the two systems. For C-70, intact molecular ions are formed in charge states up to 10+, while the maximum charge state for C-60 molecules is 9+ following collisions with Xe23+ at 69 keV. The kinetic-energy releases measured for asymmetric fission of C-70 ions (C-70(r+)-->C-68((r-1))+C-2(+)) are mostly close to the corresponding ones for C-60, while both sets of results are significantly lower than those reported for electron-impact ionization studies of C-60 and C-70. Kinetic-energy releases and fission barrier heights are estimated for C-60 and C-70 ions using an electrostatic model. An increased intensity of the higher charge states of C-70 ions is observed compared to the C-60 case, which most likely is due to a larger number of degrees of freedom on which the internal excitation energy may be distributed.}",
doi = "{10.1103/PhysRevA.69.053203}",
article-number = "{053203}",
issn = "{1050-2947}",
unique-id = "{ISI:000221813700102}"
}

64. H Zettergren, J Jensen, HT Schmidt and H Cederquist.
Electrostatic model calculations of fission barriers for fullerene ions. EUROPEAN PHYSICAL JOURNAL D 29(1):63-68, April 2004.
DOI BibTeX

@article{ ISI:000221058100010,
author = "Zettergren, H and Jensen, J and Schmidt, HT and Cederquist, H",
title = "{Electrostatic model calculations of fission barriers for fullerene ions}",
journal = "{EUROPEAN PHYSICAL JOURNAL D}",
year = "{2004}",
volume = "{29}",
number = "{1}",
pages = "{63-68}",
month = "{APR}",
abstract = "{We present model calculations of kinetic energy releases and fission barriers in asymmetric fission of C-60(r+) ions, using a simple electrostatic model where the fragments are treated as conducting spheres. The kinetic energy releases are calculated using two different approaches for deducing the radii of the spheres. Both approaches give results in qualitative agreement with experimental results. The fission barriers, oil the other hand, depend strongly on the model radii and the activation energies for neutral fragment emission. A comparison between the model calculations shows that the choice of the finite size of the smaller fragments become important as r increases and have large influences on the prediction for the C-60(r+) stability limit. The competition between neutral (evaporation) and charged-fragment emission (fission) are discussed within a static over-the-barrier model for electron transfer between conducting spheres.}",
doi = "{10.1140/epjd/e2004-00006-6}",
issn = "{1434-6060}",
unique-id = "{ISI:000221058100010}"
}

65. B Manil, L Maunoury, BA Huber, J Jensen, HT Schmidt, H Zettergren, H Cederquist, S Tomita and P Hvelplund.
Highly charged clusters of fullerenes: Charge mobility and appearance sizes. PHYSICAL REVIEW LETTERS 91(21), 2003.
DOI BibTeX

@article{ ISI:000186757000035,
author = "Manil, B and Maunoury, L and Huber, BA and Jensen, J and Schmidt, HT and Zettergren, H and Cederquist, H and Tomita, S and Hvelplund, P",
title = "{Highly charged clusters of fullerenes: Charge mobility and appearance sizes}",
journal = "{PHYSICAL REVIEW LETTERS}",
year = "{2003}",
volume = "{91}",
number = "{21}",
month = "{NOV 21}",
abstract = "{Clusters of fullerenes (C-60,C-70)(n) are produced in a gas aggregation source and are multiply ionized in collisions with highly charged Xe-20+,Xe-30+ ions. Their stabilities and decay processes are analyzed with high-resolution time-of-flight mass spectrometry. Fullerene clusters in charge states up to q=5 have been observed and appearance sizes are found to be as small as n(app)=5, 10, 21, and 33 for q=2, 3, 4, and 5, respectively. The analysis of the multicoincident fragmentation spectra indicates a high charge mobility. This is in contrast to charge localization effects which have been reported for Ar-n(q+) rare gas clusters. Clusters of fullerenes are found to be conducting when multiply charged.}",
doi = "{10.1103/PhysRevLett.91.215504}",
article-number = "{215504}",
issn = "{0031-9007}",
unique-id = "{ISI:000186757000035}"
}

66. JU Andersen, H Cederquist, JS Forster, BA Huber, P Hvelplund, J Jensen, B Liu, B Manil, L Maunoury, SB Nielsen, UV Pedersen, HT Schmidt, S Tomita and H Zettergren.
Power-law decay of collisionally excited amino acids and quenching by radiative cooling. EUROPEAN PHYSICAL JOURNAL D 25(2):139-148, August 2003.
DOI BibTeX

@article{ ISI:000184935300005,
author = "Andersen, JU and Cederquist, H and Forster, JS and Huber, BA and Hvelplund, P and Jensen, J and Liu, B and Manil, B and Maunoury, L and Nielsen, SB and Pedersen, UV and Schmidt, HT and Tomita, S and Zettergren, H",
title = "{Power-law decay of collisionally excited amino acids and quenching by radiative cooling}",
journal = "{EUROPEAN PHYSICAL JOURNAL D}",
year = "{2003}",
volume = "{25}",
number = "{2}",
pages = "{139-148}",
month = "{AUG}",
abstract = "{We have investigated the time dependence of the fragmentation of protonated amino acids stored at 22 keV in the electrostatic ring ELISA. The ions were produced in an electrospray source and after bunching in a quadrupole trap they were excited by collisions in a Ne gas. As in earlier studies of metal clusters and fullerenes produced in hot{''} ion sources we find that the dissociation of metastable molecules follows approximately a 1/t decay law until a time tau after which the yield falls off much more rapidly. We interpret this reduction as a result of radiative cooling with a characteristic cooling time, tau(c) similar or equal to G(T), where G is the magnitude of the exponent in an Arrhenius expression for the rate of the dominant fragmentation process. The values of tau obtained from fits to the data are in the range 9-17 ms corresponding to cooling times of a few hundred milliseconds, in good accord with the expected rate of cooling by emission from IR-active vibrations. The power-law behaviour for t < tau varies somewhat between the different amino acids, with powers between -0.9 and -1.1. We argue that this may be due to a competition between fragmentation channels with different Arrhenius parameters.}",
doi = "{10.1140/epjd/e2003-00093-9}",
issn = "{1434-6060}",
unique-id = "{ISI:000184935300005}"
}

67. H Cederquist, J Jensen, HT Schmidt, H Zettergren, S Tomita, BA Huber and B Manil.
Barriers for asymmetric fission of multiply charged C-60 fullerenes. PHYSICAL REVIEW A 67(6), June 2003.
DOI BibTeX

@article{ ISI:000183915200077,
author = "Cederquist, H and Jensen, J and Schmidt, HT and Zettergren, H and Tomita, S and Huber, BA and Manil, B",
title = "{Barriers for asymmetric fission of multiply charged C-60 fullerenes}",
journal = "{PHYSICAL REVIEW A}",
year = "{2003}",
volume = "{67}",
number = "{6}",
month = "{JUN}",
abstract = "{We have measured kinetic energy releases in asymmetric fission, C-60(r+)-->C-58((r-1)+)+C-2(+) (r=6-9) and evaporation C-60(r+)-->C-58(r+)+C-2 (r=2,3), following multiple-electron removal from C-60 in He2+ and Xe17+ collisions at 3q keV (q=2,17). We used the recoil-ion momentum technique and limited the initial momentum distribution of the target molecules by collimation of the effusive C-60 jet. This yielded a resolution of 3 meV for the final kinetic energies of the charged C-58 fragments, mapped out as two-dimensional position distributions at the end of a linear time-of-flight mass spectrometer. The present results for asymmetric fission are in agreement with earlier ones deduced from time-of-flight C-2(+) peak-shape and sector-field C-58((r-1)+)-energy analysis. Model calculations treating C-58((r-1)+) and C-2(+) as conducting spheres indicate that the autocharge-transfer process, which has been proposed to link asymmetric fission to neutral C-2 emission, most likely is inactive for all r. Using a charge-independent activation energy for C-2 emission from C-60(r+) of E-a=10 eV, we deduce fission barriers indicating lower (semiempirical) and upper (model) C-60(r+)-stability limits of r=11 and r=18, respectively.}",
doi = "{10.1103/PhysRevA.67.062719}",
article-number = "{062719}",
issn = "{1050-2947}",
unique-id = "{ISI:000183915200077}"
}

68. H Schmidt-Bocking, V Mergel, R Dorner, CL Cocke, O Jagutzki, L Schmidt, T Weber, HJ Ludde, E Weigold, J Berakdar, H Cederquist, HT Schmidt, R Schuch and AS Kheifets.
Revealing the non-s(2) contributions in the momentum wave function of ground-state He. EUROPHYSICS LETTERS 62(4):477-483, May 2003.
DOI BibTeX

@article{ ISI:000182961600004,
author = "Schmidt-Bocking, H and Mergel, V and Dorner, R and Cocke, CL and Jagutzki, O and Schmidt, L and Weber, T and Ludde, HJ and Weigold, E and Berakdar, J and Cederquist, H and Schmidt, HT and Schuch, R and Kheifets, AS",
title = "{Revealing the non-s(2) contributions in the momentum wave function of ground-state He}",
journal = "{EUROPHYSICS LETTERS}",
year = "{2003}",
volume = "{62}",
number = "{4}",
pages = "{477-483}",
month = "{MAY}",
abstract = "{The correlated Tunneling Transfer Ionization (TuTI) channel in fast 4-body processes p + He --> H-0 + He2+ + e is utilized to probe the highly correlated asymptotic parts of the He ground-state momentum space wave function. In this reaction, predominantly at large nuclear impact parameters, one electron in the He ground state is captured by the proton by tunneling through the two-center barrier when electron and proton velocity vectors resonantly match. The measured 3-particle final-state momentum distributions show characteristic features that we trace back to the highly correlated non-s(2) components of the He ground-state momentum wave function. This conclusion is supported by a simple heuristic model.}",
doi = "{10.1209/epl/i2003-00378-5}",
issn = "{0295-5075}",
researcherid-numbers = "{Kheifets, Anatoli/C-9131-2009 Doerner, Reinhard/A-5340-2008}",
orcid-numbers = "{Doerner, Reinhard/0000-0002-3728-4268}",
unique-id = "{ISI:000182961600004}"
}

69. J Jensen, H Zettergren, A Fardi, HT Schmidt and H Cederquist.
Energy releases in the fission of multiply charged C-60 ions. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 205:643-650, May 2003.
DOI BibTeX

@article{ ISI:000183211200125,
author = "Jensen, J and Zettergren, H and Fardi, A and Schmidt, HT and Cederquist, H",
title = "{Energy releases in the fission of multiply charged C-60 ions}",
journal = "{NUCLEAR INSTRUMENTS \& METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS}",
year = "{2003}",
volume = "{205}",
pages = "{643-650}",
month = "{MAY}",
note = "{11th International Conference on the Physics of Highly Charged Ions (HCI 2002), CAEN, FRANCE, SEP 01-06, 2002}",
abstract = "{We have studied electron-transfer and collision-induced fragmentation processes in collisions between slow highly charged ions and C-60 molecules. By using a position sensitive detector, located after a time-of-flight spectrometer, we obtain recoil energies of fragments resulting from post-collisional disintegration of multiply charged C-60 ions. We deduce kinetic energy releases (KERs) for the cases in which multiply charged C-60 ions emit either a single C-2(+) ion or a neutral C-2-unit. We find that C-58(4+) ions predominately are due to the emission of a neutral C-2 molecule. Model calculations of KER-values resulting from C-60(r+) ions emitting a C-2(+) ion are presented, and compared with the corresponding experimental results for C-60(r+) with 5 less than or equal to r less than or equal to 9 (C) 2003 Elsevier Science B.V. All rights reserved.}",
doi = "{10.1016/S0168-583X(03)00532-9}",
issn = "{0168-583X}",
unique-id = "{ISI:000183211200125}"
}

70. P Hvelplund, B Liu, SB Nielsen, S Tomita, H Cederquist, J Jensen, HT Schmidt and H Zettergren.
Electron capture and loss by protonated peptides and proteins in collisions with C-60 and Na. EUROPEAN PHYSICAL JOURNAL D 22(1):75-79, January 2003.
DOI BibTeX

@article{ ISI:000180850000009,
author = "Hvelplund, P and Liu, B and Nielsen, SB and Tomita, S and Cederquist, H and Jensen, J and Schmidt, HT and Zettergren, H",
title = "{Electron capture and loss by protonated peptides and proteins in collisions with C-60 and Na}",
journal = "{EUROPEAN PHYSICAL JOURNAL D}",
year = "{2003}",
volume = "{22}",
number = "{1}",
pages = "{75-79}",
month = "{JAN}",
abstract = "{Electron capture and loss cross-sections have been measured for collisions between fast multiply charged peptide and protein ions {[}M+nH](n+) and Na or C-60. The ions were produced in an electrospray ion source (ESI) and accelerated to an energy of n x 50 keV. We find that the size of the cross-sections depend strongly on molecule size, ionization energy and projectile charge state n. For multiply charged ubiquitin projectiles, the cross-sections for electron capture are found to be several times larger With a Na target than with a C-60 target. This observation is qualitatively explained by means of an over-the-barrier model for electron transfer using metal-sphere descriptions for the electronic responses of the collision partners.}",
doi = "{10.1140/epjd/e2002-00220-2}",
issn = "{1434-6060}",
unique-id = "{ISI:000180850000009}"
}

71. HT Schmidt, A Fardi, R Schuch, SH Schwartz, H Zettergren, H Cederquist, L Bagge, H Danared, A Kallberg, J Jensen, KG Rensfelt, V Mergel, L Schmidt, H Schmidt-Bocking and CL Cocke.
Double-to-single target ionization ratio for electron capture in fast p-He collisions. PHYSICAL REVIEW LETTERS 89(16), 2002.
DOI BibTeX

@article{ ISI:000178384300010,
author = "Schmidt, HT and Fardi, A and Schuch, R and Schwartz, SH and Zettergren, H and Cederquist, H and Bagge, L and Danared, H and Kallberg, A and Jensen, J and Rensfelt, KG and Mergel, V and Schmidt, L and Schmidt-Bocking, H and Cocke, CL",
title = "{Double-to-single target ionization ratio for electron capture in fast p-He collisions}",
journal = "{PHYSICAL REVIEW LETTERS}",
year = "{2002}",
volume = "{89}",
number = "{16}",
month = "{OCT 14}",
abstract = "{We have used the ion storage ring CRYRING and its internal gas-jet target and recoil-ion-momentum spectrometer to measure absolute cross sections for transfer ionization (TI: p+He-->H-0+He2++e(-)) in 2.5-4.5 MeV p-He collisions with separate Thomas (TTI) and kinematic (KTI) TI contributions. The probability for electron emission in kinematical capture decreases with increasing velocity and appears to approach the photoionization shakeoff value (1.63\%) {[}T. Aberg, Phys. Rev. A 2, 1726 (1970)]. The velocity dependence of the TTI cross section is consistent with the theoretically predicted v(-11) scaling {[}J. S. Briggs and K. Taulbjerg, J. Phys. B 12, 2565 (1979)].}",
doi = "{10.1103/PhysRevLett.89.163201}",
article-number = "{163201}",
issn = "{0031-9007}",
unique-id = "{ISI:000178384300010}"
}

72. H Zettergren, HT Schmidt, H Cederquist, J Jensen, S Tomita, P Hvelplund, H Lebius and BA Huber.
Static over-the-barrier model for electron transfer between metallic spherical objects. PHYSICAL REVIEW A 66(3), September 2002.
DOI BibTeX

@article{ ISI:000178382500069,
author = "Zettergren, H and Schmidt, HT and Cederquist, H and Jensen, J and Tomita, S and Hvelplund, P and Lebius, H and Huber, BA",
title = "{Static over-the-barrier model for electron transfer between metallic spherical objects}",
journal = "{PHYSICAL REVIEW A}",
year = "{2002}",
volume = "{66}",
number = "{3}",
month = "{SEP}",
abstract = "{We present a static classical over-the-barrier model (OBM) for electron transfer between two isolated, infinitely conducting spheres with arbitrary and different electrical charges. This model is shown to be very useful for first estimates of single- and multiple-electron transfer cross sections in cluster-cluster collisions when the collision velocities are significantly lower than the typical target electron velocities. For faster collisions, more advanced models such as the dynamical OBM, or the time-dependent local density approximation (TDLDA) or the solutions of their semiclassical counterparts-the Vlasov equations have to be used. The latter two methods clearly provide the most detailed information on the electronic response, but they are also computationally very demanding and have, so far, only been used for collisions involving one cluster (and an atomic ion). We compare our static OBM results (in the limit in which one of the sphere radii approaches zero) with TDLDA and Vlasov calculations of cluster charging in Ar8+-Na-40 collisions at different velocities to demonstrate that the present static OBM is valid at sufficiently low velocities. The static OBM is then used in a comparison with experimental target charge state distributions in C-60(q+)-C-60 and Cq+-C-60 collisions at 0.01rootq and 0.06rootq v(0), respectively. Calculated electronic excitation of the projectile after two-electron transfer in C-60(4+)-C-60 collisions readily explains the recently observed suppression of the transfer ionization channel in this reaction. Finally, we model the total projectile electron loss and dissociation cross section in highly protonated Lysozyme-oxygen (Lys-H-9(9+)-O-2) collisions and make comparisons with recent experimental results at 0.01 v(0).}",
doi = "{10.1103/PhysRevA.66.032710}",
article-number = "{032710}",
issn = "{1050-2947}",
unique-id = "{ISI:000178382500069}"
}

73. A Le Padellec, F Rabilloud, D Pegg, A Neau, F Hellberg, R Thomas, HT Schmidt, M Larsson, H Danared, A Kallberg, K Andersson and D Hanstorp.
Electron-impact detachment and dissociation of C-4(-) ions. JOURNAL OF CHEMICAL PHYSICS 115(23):10671-10677, 2001.
DOI BibTeX

@article{ ISI:000172536000011,
author = "Le Padellec, A and Rabilloud, F and Pegg, D and Neau, A and Hellberg, F and Thomas, R and Schmidt, HT and Larsson, M and Danared, H and Kallberg, A and Andersson, K and Hanstorp, D",
title = "{Electron-impact detachment and dissociation of C-4(-) ions}",
journal = "{JOURNAL OF CHEMICAL PHYSICS}",
year = "{2001}",
volume = "{115}",
number = "{23}",
pages = "{10671-10677}",
month = "{DEC 15}",
abstract = "{CRYRING was used to study collision processes between an electron and a negative ion cluster C-4(-). The total detachment cross sections for the production of the neutral 4C, 3C, 2C, and C fragments were measured. The cross sections for pure detachment, and for detachment plus dissociation leading to the production of C-3+C, 2C(2), and C-2+2C were extracted using a grid. It was found that the pure detachment process overwhelmingly dominates all other fragmentation processes. The threshold location for the detachment channel is found to be around 6.0 eV. Although the doubly charged negative ion C-4(2-) has received little previous attention, a defined near-threshold resonance observed in the detachment cross section curve, has been associated with the short-lived state C-4(2-) (0.7 fs lifetime). (C) 2001 American Institute of Physics.}",
doi = "{10.1063/1.1421068}",
issn = "{0021-9606}",
researcherid-numbers = "{Rabilloud, Franck/H-4254-2012}",
unique-id = "{ISI:000172536000011}"
}

74. A Le Padellec, K Andersson, D Hanstorp, F Hellberg, M Larsson, A Neau, S Rosen, HT Schmidt, R Thomas, J Semaniak, DJ Pegg, F Osterdahl, H Danared and A Kallberg.
Electron scattering on CN-. PHYSICA SCRIPTA 64(5):467-473, November 2001.
BibTeX

@article{ ISI:000172383000013,
author = "Le Padellec, A and Andersson, K and Hanstorp, D and Hellberg, F and Larsson, M and Neau, A and Rosen, S and Schmidt, HT and Thomas, R and Semaniak, J and Pegg, DJ and Osterdahl, F and Danared, H and Kallberg, A",
title = "{Electron scattering on CN-}",
journal = "{PHYSICA SCRIPTA}",
year = "{2001}",
volume = "{64}",
number = "{5}",
pages = "{467-473}",
month = "{NOV}",
abstract = "{We present the results of an experiment in which electrons have been scattered on CN- ions, over a collision energy range 0-60 eV The experiment was performed at the heavy ion storage ring CRYRING The CN- ions were stored in the ring and merged with a monoenergetic electron beam that was guided in to and out of the ring using strong magnetic fields. Both neutral and positive fragments from the collision process were detected with surface barrier detectors. It was found that pure detachment completely dominates over those channels which involves breaking the molecular bond. The threshold energy for the detachment process was found to be 7 eV The cross section rose from zero to a maximum of about 5.10(-16) cm(2) just below 30 eV, after which it remained essentially constant. The threshold region was carefully investigated in an attempt to find resonance structure arising from the possible existence of the doubly charged ion, CN2-. The statistical uncertainty in the data was, however, too large to conclusively prove or disprove the existence of such a resonance.}",
issn = "{0031-8949}",
unique-id = "{ISI:000172383000013}"
}

75. A Langereis, J Jensen, A Fardi, K Haghighat, HT Schmidt, SH Schwartz, H Zettergren and H Cederquist.
Stabilization of electrons on Arq+ ions after slow collisions with C-60. PHYSICAL REVIEW A 63(6), June 2001.
BibTeX

@article{ ISI:000169134800056,
author = "Langereis, A and Jensen, J and Fardi, A and Haghighat, K and Schmidt, HT and Schwartz, SH and Zettergren, H and Cederquist, H",
title = "{Stabilization of electrons on Arq+ ions after slow collisions with C-60}",
journal = "{PHYSICAL REVIEW A}",
year = "{2001}",
volume = "{63}",
number = "{6}",
month = "{JUN}",
abstract = "{We discuss hollow atom formation and stabilization of electrons on Arq+ following Arq+ + C-60 --> Ar(q-s)+ +... collisions at 3.3q keV (q = 4-18). The experimental information consists of the final projectile charge-state distributions f(q)(s), i.e., the relative distributions of the number of stabilized electrons, s, and the corresponding mean values <s> = Sigma (q)(s) = (1)sf(q)(s) as functions of q. We use the classical over-the-barrier model to deduce sequences of effective principal quantum numbers and find that the hollow atom formation is completed 3-4a(0) above the surface of the C-60 cage for all q. For q less than or equal to8 (filled L shells), the last electrons are transferred from delocalized outer C-60 orbitals directly to the projectile M shell (side-feeding), while several intermediate shells are left open for larger q leading to further electron transfer at intermediate distances and simultaneous electron emission from higher projectile shells. At still closer distances, localized carbon K-shell electrons are transferred directly to the argon L (q = 10 and 11) and M shells (q greater than or equal to 12). The direct transfer to the L shell of Ar10+ and Ar11+ is manifested as significant enhancements of (s) for q = 10 and q = 11.}",
article-number = "{062725}",
issn = "{1050-2947}",
unique-id = "{ISI:000169134800056}"
}

76. K Andersson, D Hanstorp, A Neau, S Rosen, HT Schmidt, R Thomas, M Larsson, J Semaniak, F Osterdahl, H Danared, A Kallberg and A Le Padellec.
Electron impact single detachment on the F- ions using the heavy ion storage ring CRYRING: Cross-section determination. EUROPEAN PHYSICAL JOURNAL D 13(3):323-328, March 2001.
DOI BibTeX

@article{ ISI:000167533100004,
author = "Andersson, K and Hanstorp, D and Neau, A and Rosen, S and Schmidt, HT and Thomas, R and Larsson, M and Semaniak, J and Osterdahl, F and Danared, H and Kallberg, A and Le Padellec, A",
title = "{Electron impact single detachment on the F- ions using the heavy ion storage ring CRYRING: Cross-section determination}",
journal = "{EUROPEAN PHYSICAL JOURNAL D}",
year = "{2001}",
volume = "{13}",
number = "{3}",
pages = "{323-328}",
month = "{MAR}",
abstract = "{Electron Impact Single Detachment (EISD) of F- has been studied using the heavy ion storage ring CRYRING at the Manne Siegbahn Laboratory, Stockholm, Sweden. F- ions stored in the ring were merged with an electron beam in one of the ring sections. Neutral F atoms produced in the EISD process were detected in the zero-degree direction using a surface barrier detector. The threshold for the detachment process was found to be around 7.6 eV, thus more than twice the binding energy of F-. The cross-sections increased smoothly up to 55 eV where it reached a maximum of 1.9 x 10(-16) cm(2). At higher energies slow decrease of the cross-section was observed. which follows the energy dependence predicted by the Bethe-Born approximation. The experiment showed that CRYRING can be used favourably for studies of anions, and several experiments ale forthcoming.}",
doi = "{10.1007/s100530170248}",
issn = "{1434-6060}",
unique-id = "{ISI:000167533100004}"
}

77. HT Schmidt, H Cederquist, J Jensen and A Fardi.
Conetrap: A compact electrostatic ion trap. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 173(4):523-527, February 2001.
DOI BibTeX

@article{ ISI:000166721500016,
author = "Schmidt, HT and Cederquist, H and Jensen, J and Fardi, A",
title = "{Conetrap: A compact electrostatic ion trap}",
journal = "{NUCLEAR INSTRUMENTS \& METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS}",
year = "{2001}",
volume = "{173}",
number = "{4}",
pages = "{523-527}",
month = "{FEB}",
abstract = "{We have developed a very simple and compact fully electrostatic ion storage device. It consists of only three electrodes: two conical and one central cylindrical. This simple setup works as two focusing electrostatic mirrors forming a resonator-like structure and thereby confining the ions. We present the design and show the first test results demonstrating an ion-storage lifetime in the 100 ms-range at modest vacuum conditions. Storage lifetimes in the order of minutes are foreseen when UHV conditions are introduced. (C) 2001 Elsevier Science B.V. All rights reserved.}",
doi = "{10.1016/S0168-583X(00)00415-8}",
issn = "{0168-583X}",
unique-id = "{ISI:000166721500016}"
}

78. H Cederquist, P Hvelplund, H Lebius, HT Schmidt, S Tomita and BA Huber.
Nonfragmenting charge transfer in slow peripheral C-60(q+)-C-60 collisions. PHYSICAL REVIEW A 63(2), February 2001.
DOI BibTeX

@article{ ISI:000166867900125,
author = "Cederquist, H and Hvelplund, P and Lebius, H and Schmidt, HT and Tomita, S and Huber, BA",
title = "{Nonfragmenting charge transfer in slow peripheral C-60(q+)-C-60 collisions}",
journal = "{PHYSICAL REVIEW A}",
year = "{2001}",
volume = "{63}",
number = "{2}",
month = "{FEB}",
abstract = "{We have investigated electron transfer and fragmentation of C-60 molecules in slow (1q-2q keV) collisions with C-60(q+) projectiles (q = 2-5) and atomic Cq+ projectiles at somewhat higher velocities. While the latter give the characteristic fragment distributions the former only yield intact C-60(r+) target molecules. Further, the atomic carbon projectiles ionize the target C-60 up to their incident charges, r(max) = q, while the maximum target charges are limited to r(max) = Int{[}(q + 1)/2] for C-60(q+) projectiles. The latter results are explained by considering the energy minima for q charges distributed on the equipotential surfaces of two touching spheres.}",
doi = "{10.1103/PhysRevA.63.025201}",
article-number = "{025201}",
issn = "{1050-2947}",
unique-id = "{ISI:000166867900125}"
}

79. SH Schwartz, A Fardi, K Haghighat, A Langereis, HT Schmidt and H Cederquist.
Absolute and total electron-capture cross sections in slow Arq+-C-60 collisions. PHYSICAL REVIEW A 63(1), January 2001.
BibTeX

@article{ ISI:000166383000072,
author = "Schwartz, SH and Fardi, A and Haghighat, K and Langereis, A and Schmidt, HT and Cederquist, H",
title = "{Absolute and total electron-capture cross sections in slow Arq+-C-60 collisions}",
journal = "{PHYSICAL REVIEW A}",
year = "{2001}",
volume = "{63}",
number = "{1}",
month = "{JAN}",
abstract = "{We present experimental absolute and total electron-capture cross sections for Arq+-C-60 (q = 4, 6, and 8-18) collisions at 3.3q keV. The absolute scale is based on the C-60 vapor pressure by Abrefah et al. {[}Appl. Phys. Lett. 60, 1313 (1992)], which together with the results of Mathews et al. {[}J. Phys. Chem. 96, 3566, (1992)] are the only possible choices among the many, widely dispersed, vapor pressures reported in the literature. In order to support this statement, we calculate total electron-capture cross sections modeling C-60 as a pointlike object and as an infinitely conducting sphere (ICS). These model results are shown to differ little, since polarization and finite-size effects are relatively unimportant for the distant collisions at which the outermost (first) electrons me transferred. We are thus able to use the semiempirical formula for absolute ion-atom cross sections by Selberg et nl. {[}Phys. Rev. A 54, 4127 (1996)], treating C-60 as a hypothetical atom with ionization potential I-1 = 7.6 eV, and the ICS model to define lower and upper bounds for the absolute cross-section scale. We find significant oscillations in the total electron-capture cross sections as functions of q.}",
article-number = "{013201}",
issn = "{1050-2947}",
unique-id = "{ISI:000166383000072}"
}

80. J Opitz, H Lebius, S Tomita, BA Huber, PM Capelle, DB Montesquieu, AB Montesquieu, A Reinkoster, U Werner, HO Lutz, A Niehaus, M Benndorf, K Haghighat, HT Schmidt and H Cederquist.
Electronic excitation in H+-C-60 collisions: Evaporation and ionization. PHYSICAL REVIEW A 62(2), August 2000.
DOI BibTeX

@article{ ISI:000088683400057,
author = "Opitz, J and Lebius, H and Tomita, S and Huber, BA and Capelle, PM and Montesquieu, DB and Montesquieu, AB and Reinkoster, A and Werner, U and Lutz, HO and Niehaus, A and Benndorf, M and Haghighat, K and Schmidt, HT and Cederquist, H",
title = "{Electronic excitation in H+-C-60 collisions: Evaporation and ionization}",
journal = "{PHYSICAL REVIEW A}",
year = "{2000}",
volume = "{62}",
number = "{2}",
month = "{AUG}",
abstract = "{We have studied energy transfer, fragmentation and ionization in collisions between protons and C-60 molecules. The collision energy is varied between 1 and 300 keV and we thus cover a velocity range from 0.2 to 3.5 atomic units. The distributions of intact and fragmented C-60 ions have been measured by means of time-of-flight mass spectrometry using pulsed beams or emitted electrons to clock the collision events. The processes leading to multiple ionization and evaporation of neutral dimers are analyzed as functions of the projectile velocity. In contrast to recent findings for He+-C-60 collisions by Schlatholter et al., our results show that the cross sections for ionization and evaporation first increase with velocity, have maxims at around 1-2 a.u., and decrease again for higher velocities. This velocity dependence closely resembles the one for the electronic stopping power indicating that electronic excitations are the main means of energy transfer to C-60 and that this energy is rapidly distributed among the vibrational degrees of freedom. This conclusion is supported by Monte Carlo calculations of nuclear and electronic energy loss for protons passing through and closely outside the C-60 cage.}",
doi = "{10.1103/PhysRevA.62.022705}",
article-number = "{022705}",
issn = "{1050-2947}",
researcherid-numbers = "{Werner, Udo/B-6109-2012}",
unique-id = "{ISI:000088683400057}"
}

81. H Cederquist, A Fardi, K Haghighat, A Langereis, HT Schmidt, H Schwartz, JC Levin, IA Sellin, H Lebius, B Huber, MO Larsson and P Hvelplund.
Electronic response of C(60) in slow collisions with highly charged ions. PHYSICAL REVIEW A 61(2), February 2000.
DOI BibTeX

@article{ ISI:000085336900062,
author = "Cederquist, H and Fardi, A and Haghighat, K and Langereis, A and Schmidt, HT and Schwartz, H and Levin, JC and Sellin, IA and Lebius, H and Huber, B and Larsson, MO and Hvelplund, P",
title = "{Electronic response of C(60) in slow collisions with highly charged ions}",
journal = "{PHYSICAL REVIEW A}",
year = "{2000}",
volume = "{61}",
number = "{2}",
month = "{FEB}",
abstract = "{We present measurements of projectile angular differential cross sections, d sigma/d theta, and mean projectile energy gain or loss, Delta E(mean), as functions of the number s of electrons stabilized on the projectile in 16- and 26.4-keV Ar(8+) + C(60) --> Ar((8-s)+) + C(60)(r+) + (r-s)e(-) collisions. These results are discussed in view of two models of the electronic response of C(60). In the infinitely conducting sphere model the charge mobility is sufficiently high in order to average out all effects of localization of individual charge carriers. In the movable-hole model positive holes{''} are assumed to be localized as point charges in their equilibrium positions on the molecular surface{''} within thr times (down to 10(-16) s) between sequential over-the-barrier electron transfers. The two sets of predictions for theta are close for r less than or equal to 8, and for r less than or equal to 5 they are also in agreement with experimental results indicating ultrafast electronic response of ionized C(60). For r > 5, both models underestimate theta and therefore we have developed Monte Carlo calculations for close collisions with individual carbon atoms in C(60). The energy gain first increases with s, has a flat maximum around s = 4 and yields mean energy loss Delta E(mean) = -20 +/- 5 eV for s = 7. The measured fragmentation spectra theta(s) and Delta E(mean)(s) may be partially rationalized by combining each of the two smooth-sphere models with the Monte Carlo calculations for close collisions.}",
doi = "{10.1103/PhysRevA.61.022712}",
article-number = "{022712}",
issn = "{1050-2947}",
unique-id = "{ISI:000085336900062}"
}

82. A Fardi, H Cederquist and HT Schmidt.
Lifetime measurements for metastable He-like ions. HYPERFINE INTERACTIONS 127(1-4):247-250, 2000.
DOI BibTeX

@article{ ISI:000088519000037,
author = "Fardi, A and Cederquist, H and Schmidt, HT",
title = "{Lifetime measurements for metastable He-like ions}",
journal = "{HYPERFINE INTERACTIONS}",
year = "{2000}",
volume = "{127}",
number = "{1-4}",
pages = "{247-250}",
note = "{1st Euroconference on Atomic Physics at Accelerators (APAC 99), JOHANNES GUTENBERG UNIV, MAINZ, GERMANY, SEP 19-24, 1999}",
abstract = "{We present work in progress on the development of a new technique for measurements of mu s lifetimes of metastable excited states of He-like ions. The key element in this new technique is an electrostatic storage device for ions with keV energies.}",
doi = "{10.1023/A:1012603919983}",
issn = "{0304-3843}",
unique-id = "{ISI:000088519000037}"
}

83. K Hansen, JU Andersen, H Cederquist, C Gottrup, P Hvelplund, MO Larsson, VV Petrunin and HT Schmidt.
Thermionic emission laser spectroscopy of stored C-60(-). EUROPEAN PHYSICAL JOURNAL D 9(1-4, SI):351-354, December 1999.
DOI BibTeX

@article{ ISI:000087317100068,
author = "Hansen, K and Andersen, JU and Cederquist, H and Gottrup, C and Hvelplund, P and Larsson, MO and Petrunin, VV and Schmidt, HT",
title = "{Thermionic emission laser spectroscopy of stored C-60(-)}",
journal = "{EUROPEAN PHYSICAL JOURNAL D}",
year = "{1999}",
volume = "{9}",
number = "{1-4, SI}",
pages = "{351-354}",
month = "{DEC}",
note = "{9th International Symposium of Small Particles and Inorganic Clusters, LAUSANNE, SWITZERLAND, SEP 01-05, 1998}",
organization = "{Swiss Fed Inst Technol, Dept Phys; Swiss Natl Sci Fdn; Swiss Acad Sci; Univ Lausanne; Schweizer Gesell Nanowissensch \& Nanotechn}",
abstract = "{Thermal emission of electrons from clusters is enhanced after the absorption of photons. We have used this process to measure the photoabsorption cross sections of hot C-60 anions in the visible and near-infrared part of the spectrum, using the ion storage ring ASTRID (Aarhus STorage RIng, Denmark).}",
doi = "{10.1007/s100530050454}",
issn = "{1434-6060}",
researcherid-numbers = "{Hansen, Klavs/J-1959-2012}",
unique-id = "{ISI:000087317100068}"
}

84. HB Pedersen, N Djuric, MJ Jensen, D Kella, CP Safvan, HT Schmidt, L Vejby-Christensen and LH Andersen.
Electron collisions with diatomic anions. PHYSICAL REVIEW A 60(4):2882-2899, October 1999.
DOI BibTeX

@article{ ISI:000083201000047,
author = "Pedersen, HB and Djuric, N and Jensen, MJ and Kella, D and Safvan, CP and Schmidt, HT and Vejby-Christensen, L and Andersen, LH",
title = "{Electron collisions with diatomic anions}",
journal = "{PHYSICAL REVIEW A}",
year = "{1999}",
volume = "{60}",
number = "{4}",
pages = "{2882-2899}",
month = "{OCT}",
abstract = "{Electron collisions with negative ions (B-2(-), C-2(-), O-2(-), BN-, and OH) have been performed in a merged-beams experiment at the heavy-ion storage ring ASTRID (Aarhus Storage Ring, Denmark). Absolute cross sections for detachment (e(-) + AB(-)-->AB(0) + 2e(-)) and detachment plus dissociation (e(-) + AB(-)-->A(0) + B-0 +2e(-)) are reported for energies below 40 eV. For the homonuclear ions, X-2(-) (X = B, C, O), cross sections are also presented for dissociative reactions leading to an X- particle in the final state. The detachment process is dominant for all investigated systems. The detachment cross section is characterized by an effective threshold larger than the electron binding energy. The shapes of the detachment cross sections are similar for the studied anions pointing to a common nonresonant mechanism for detachment. Also, the cross section for detachment plus dissociation and pure dissociation show regularities pointing to a general nonresonant mechanism. Structures are observed in the detachment cross section of C-2(-) and BN- and in the dissociation cross section of B-2(-) and C-2(-). The structures are attributed to short-lived dianions (resonances) formed during the collision process. The results are supported by ab initio calculations, and it is inferred that electronic excitations are important in the resonant reactions. {[}S1050-2947(99)05109-4].}",
doi = "{10.1103/PhysRevA.60.2882}",
issn = "{1050-2947}",
unique-id = "{ISI:000083201000047}"
}

85. IA Sellin, JC Levin, HT Schmidt, SH Schwartz, A Fardi, K Haghighat, H Cederquist, L Liljeby and A Langereis.
Absolute rates for radiative and non-radiative collisional deexcitation of metastable He+ (2s) in targets of variable polarizability. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 154(1-4):83-89, June 1999.
DOI BibTeX

@article{ ISI:000081399600012,
author = "Sellin, IA and Levin, JC and Schmidt, HT and Schwartz, SH and Fardi, A and Haghighat, K and Cederquist, H and Liljeby, L and Langereis, A",
title = "{Absolute rates for radiative and non-radiative collisional deexcitation of metastable He+ (2s) in targets of variable polarizability}",
journal = "{NUCLEAR INSTRUMENTS \& METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS}",
year = "{1999}",
volume = "{154}",
number = "{1-4}",
pages = "{83-89}",
month = "{JUN}",
note = "{7th Workshop on Fast Ion-Atom Collisions, DEBRECEN, HUNGARY, SEP 09-11, 1998}",
organization = "{BIOGAL Pharmaceut Factory; Chamber of Commerce \& Ind Hajdu-Bihar County; City Council Debrecen; County Council Hadju-Bihar; Hungarian Acad Sci, Budapest; Hungarian Sci Res Fdn, Budapest; Natl Comm Tech Dev, Budapest; Paks Nuclear Power Plant Co; Pfeiffer Vacuum Austria; univ Fdn, Debrecen}",
abstract = "{A method devised to measure separate absolute rates for deexcitation of metastable hydrogenic atoms and ions via radiative (R) and non-radiative (NR, e.g. Penning ionization (PI)) processes has first been applied to 6.6 keV He+(2s) collisions in Ar. Preliminary results of this new method were presented at the 1997 Budapest ISIAC conference by Henning Schmidt; subsequently, refined results have been published in the June 1998 issue of Phys. Rev. A, Rapid Communications, p. R4082. Additional data for the same projectiles have now been acquired for He and Xe targets. Preliminary comparisons of the R and NR rates for these new targets with the now final results for Ar as well as comparisons of the corresponding branching ratios are the primary focus of this paper. (C) 1999 Elsevier Science B.V. All rights reserved.}",
doi = "{10.1016/S0168-583X(99)00024-5}",
issn = "{0168-583X}",
unique-id = "{ISI:000081399600012}"
}

86. H Cederquist, A Fardi, K Haghighat, A Langereis, HT Schmidt and SH Schwartz.
Highly charged ions colliding with atoms, surfaces and clusters. PHYSICA SCRIPTA T80A:46-51, 1999.
DOI BibTeX

@article{ ISI:000082093000007,
author = "Cederquist, H and Fardi, A and Haghighat, K and Langereis, A and Schmidt, HT and Schwartz, SH",
title = "{Highly charged ions colliding with atoms, surfaces and clusters}",
journal = "{PHYSICA SCRIPTA}",
year = "{1999}",
volume = "{T80A}",
pages = "{46-51}",
note = "{IX International Conference on Physics of Highly Charged Ions, BENSHEIM, GERMANY, SEP 09-14, 1998}",
abstract = "{in this review we will start out with an effort to describe the present understanding of the dominant mechanisms for electron transfer in collisions between slow highly charged ions and atoms. We then follow up with an account of the most prominent phenomena in highly charged ion-surface collisions and emphasize the similarities and differences between the collision scenarios for atomic and surface targets Finally we will discuss recent advances in the much less mature field of highly charged ion-cluster (mainly C-60) collisions.}",
doi = "{10.1238/Physica.Topical.080a00046}",
issn = "{0281-1847}",
unique-id = "{ISI:000082093000007}"
}

87. H Cederquist, A Fardi, K Haghighat, B Huber, P Hvelplund, A Langereis, MO Larsson, H Lebius, HT Schmidt and SH Schwartz.
Angular differential cross sections and mean energy gain for single- and multiple-electron capture in slow Ar8+-C-60 collisions. PHYSICA SCRIPTA T80B:203-204, 1999.
DOI BibTeX

@article{ ISI:000082093100013,
author = "Cederquist, H and Fardi, A and Haghighat, K and Huber, B and Hvelplund, P and Langereis, A and Larsson, MO and Lebius, H and Schmidt, HT and Schwartz, SH",
title = "{Angular differential cross sections and mean energy gain for single- and multiple-electron capture in slow Ar8+-C-60 collisions}",
journal = "{PHYSICA SCRIPTA}",
year = "{1999}",
volume = "{T80B}",
pages = "{203-204}",
note = "{IX International Conference on Physics of Highly Charged Ions, BENSHEIM, GERMANY, SEP 09-14, 1998}",
abstract = "{We present experimental results for angular differential cross sections, d sigma/d theta, and mean translational energy gain, Delta E-mean, as functions of the number of electrons, s, stabilized on the projectile in 26.4 keV Ar8++C-60 --> Ar(8-s)++C-60(r+)(r-s)e(-) collisions. The most probable scattering angle increases linearly with s for s=1-7, while processes leading to neutralization (s=8) scatter more strongly than expected from this trend. The Delta E-mean-values are positive and increase with s between s=1 and s=2, are virtually constant up to s=6, and finally decrease to negative values (energy loss) for s=7. The experimental results are compared with Monte Carlo trajectory simulations for impact parameters ranging from small to large values.}",
doi = "{10.1238/Physica.Topical.080a00203}",
issn = "{0281-1847}",
unique-id = "{ISI:000082093100013}"
}

88. HT Schmidt, A Fardi, K Haghighat, A Langereis, JC Levin, L Liljeby, IA Sellin, SH Schwartz and H Cederquist.
Radiative and nonradiative collisional deexcitation of metastable hydrogen-like ions. PHYSICA SCRIPTA T80B:403-404, 1999.
DOI BibTeX

@article{ ISI:000082093100095,
author = "Schmidt, HT and Fardi, A and Haghighat, K and Langereis, A and Levin, JC and Liljeby, L and Sellin, IA and Schwartz, SH and Cederquist, H",
journal = "{PHYSICA SCRIPTA}",
year = "{1999}",
volume = "{T80B}",
pages = "{403-404}",
note = "{IX International Conference on Physics of Highly Charged Ions, BENSHEIM, GERMANY, SEP 09-14, 1998}",
abstract = "{A method is presented to measure separate cross sections for collisional deexcitation of metastable ions via radiative and non-radiative processes. The principle of the experiment is to first determine the total collisional deexcitation cross section in an attenuation-like measurement. After this the non-radiative part is determined separately in a measurement where the ionized target atom (unique to the non-radiative process) is detected. Here we discuss recently published results on deexcitation of metastable He+(2s) ions colliding with Ar at 1.65 keV/amu {[}H. T. Schmidt et al., Phys. Rev A 57, R4082 (1998) and Phys. Rev. A 58 (1998)] as well as preliminary results for a Xe target. In both cases we find that the dominating contribution from radiative deexcitation agrees with the result of a semi-classical calculation of the 2s-2p mixing driven by the induced dipole held of the target atom modified by taking competing processes, for which we measured the cross sections, into account. Finally the extension to H-like projectile ions in higher charge states is discussed.}",
doi = "{10.1238/Physica.Topical.080a00403}",
issn = "{0281-1847}",
unique-id = "{ISI:000082093100095}"
}

89. HT Schmidt, SH Schwartz, J Weimar, R Schuch, H Cederquist, L Bagge, A Kallberg, J Hilke, KG Rensfelt, V Mergel, M Achler, R Dorner, R Moshammer, H Schmidt-Bocking, H Reich, M Unverzagt, W Schmitt and J Ullrich.
Status report on the internal gas-jet target for the heavy-ion storage ring CRYRING. PHYSICA SCRIPTA T80B:527-528, 1999.
DOI BibTeX

@article{ ISI:000082093100145,
author = "Schmidt, HT and Schwartz, SH and Weimar, J and Schuch, R and Cederquist, H and Bagge, L and Kallberg, A and Hilke, J and Rensfelt, KG and Mergel, V and Achler, M and Dorner, R and Moshammer, R and Schmidt-Bocking, H and Reich, H and Unverzagt, M and Schmitt, W and Ullrich, J",
title = "{Status report on the internal gas-jet target for the heavy-ion storage ring CRYRING}",
journal = "{PHYSICA SCRIPTA}",
year = "{1999}",
volume = "{T80B}",
pages = "{527-528}",
note = "{IX International Conference on Physics of Highly Charged Ions, BENSHEIM, GERMANY, SEP 09-14, 1998}",
abstract = "{A supersonic gas-jet target for investigations of the detailed collision dynamics in fast ion-atom collisions by means of recoil-ion-momentum spectroscopy has been constructed for insertion into the heavy-ion storage ring CRYRING, situated at the Manne Siegbahn Laboratory, Stockholm University. The aim is to create a target with a density of 10(12) cm(-3) and a temperature of less than 10 mK (for the case of a He target) without seriously affecting the excellent vacuum conditions of CRYRING. The gas target will become a part of the storage ring, and hence fast beams of protons, highly-charged ions, and molecular ions will be available as projectiles. Here we present test results for parts of the system. These all indicate that the design criteria will be fulfilled.}",
doi = "{10.1238/Physica.Topical.080a00527}",
issn = "{0281-1847}",
researcherid-numbers = "{Doerner, Reinhard/A-5340-2008}",
orcid-numbers = "{Doerner, Reinhard/0000-0002-3728-4268}",
unique-id = "{ISI:000082093100145}"
}

90. HT Schmidt, SH Schwartz, A Fardi, K Haghighat, H Cederquist, L Liljeby, A Langereis, JC Levin and IA Sellin.
Method for determining absolute partial cross sections for radiative and nonradiative deexcitation of metastable hydrogenlike ions. PHYSICAL REVIEW A 58(4):2887-2894, October 1998.
DOI BibTeX

@article{ ISI:000076373900041,
author = "Schmidt, HT and Schwartz, SH and Fardi, A and Haghighat, K and Cederquist, H and Liljeby, L and Langereis, A and Levin, JC and Sellin, IA",
title = "{Method for determining absolute partial cross sections for radiative and nonradiative deexcitation of metastable hydrogenlike ions}",
journal = "{PHYSICAL REVIEW A}",
year = "{1998}",
volume = "{58}",
number = "{4}",
pages = "{2887-2894}",
month = "{OCT}",
abstract = "{In this work we present a method developed to measure separately the radiative and nonradiative contributions to the cross section for collisional deexcitation of metastable hydrogenlike ions. We present the results of the first experiment applying this method, where deexcitation of metastable He+(2s) ions in collisions with argon atoms is considered. First the total deexcitation cross section for 6.6 keV He-4(+)(2s) ions is measured absolutely in a beam-gas attenuation experiment. Then the absolute cross section for nonradiative deexcitation is measured separately by coincident detection of projectiles keeping their initial charge state 1+ and recoil ions (formed only in nonradiative deexcitation events). Further, we discuss a semiclassical calculation of the radiative deexcitation cross section, in which the influence of competing electron-capture processes is taken into account in a semiempirical fashion. The result is in agreement with the measured radiative deexcitation cross section of (5.4+/- 1.3)x 10(-16) cm(2), which amounts to (70+/- 8)\% Of the total deexcitation cross section. {[}S1050-2947(98)04110-9].}",
doi = "{10.1103/PhysRevA.58.2887}",
issn = "{1050-2947}",
unique-id = "{ISI:000076373900041}"
}

91. MO Larsson, P Hvelplund, MC Larsen, H Shen, H Cederquist and HT Schmidt.
Electron capture and energy loss in similar to 100 keV collisions of atomic and molecular ions on C-60. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 177(1):51-62, 1998.
DOI BibTeX

@article{ ISI:000075467700006,
author = "Larsson, MO and Hvelplund, P and Larsen, MC and Shen, H and Cederquist, H and Schmidt, HT",
title = "{Electron capture and energy loss in similar to 100 keV collisions of atomic and molecular ions on C-60}",
journal = "{INTERNATIONAL JOURNAL OF MASS SPECTROMETRY}",
year = "{1998}",
volume = "{177}",
number = "{1}",
pages = "{51-62}",
month = "{AUG 3}",
abstract = "{We have determined absolute attenuation and electron capture cross sections in similar to 100 keV collisions between atomic ions of moderate charge states (He+, He2+, Ar2+, Ar3+, Ar4+, Xe2+, Xe3+, Xe4+) and C-60 molecules in the gas phase. The measured cross-sections support previous findings of the charge dynamics within C-60 from electron capture experiments with higher ionic charges. For a non-negligible fraction of the capture events we observed substantial ionic energy loss (less than or equal to 2 keV), which is ascribed to collisions where the ion passes through the C-60 molecule. Furthermore, we found that a molecular ion (100 keV CO22+) that captures an electron from C-60 can lose similar amounts of energy without dissociating. It is concluded that the predominant contribution to the ionic energy loss comes from electron excitation and ionization. (Int J Mass Spectrom 177 (1998) 51-62). (C) 1998 Elsevier Science B.V.}",
doi = "{10.1016/S1387-3806(98)14029-0}",
issn = "{1387-3806}",
unique-id = "{ISI:000075467700006}"
}

92. HT Schmidt, SH Schwartz, H Cederquist, L Liljeby, JC Levin and IA Sellin.
Absolute rates for radiative and nonradiative collisional deexcitation of metastable He+(2s) ions. PHYSICAL REVIEW A 57(6):R4082-R4085, June 1998.
DOI BibTeX

@article{ ISI:000074160600003,
author = "Schmidt, HT and Schwartz, SH and Cederquist, H and Liljeby, L and Levin, JC and Sellin, IA",
title = "{Absolute rates for radiative and nonradiative collisional deexcitation of metastable He+(2s) ions}",
journal = "{PHYSICAL REVIEW A}",
year = "{1998}",
volume = "{57}",
number = "{6}",
pages = "{R4082-R4085}",
month = "{JUN}",
abstract = "{A method devised to measure separate absolute rates for deexcitation of metastable hydrogenic atoms and ions via radiative and nonradiative processes is applied in a pilot study of 6.6-keV He+(2s)-Ar -->He+(1s)-... collisions. An absolute total deexcitation cross section sigma(de)(tot)= (7.6 +/- 1.2)X 10(-16) cm(2) was measured by attenuation. The cross section for nonradiative deexcitation was then measured independently. A radiative branching ratio R-BR=(70 +/- 8)\% was determined, without requiring absolute photon detection calibrations. The measured radiative deexcitation cross section agrees with the result of a semiclassical calculation when competing capture and ionization precesses are taken into account.}",
doi = "{10.1103/PhysRevA.57.R4082}",
issn = "{1050-2947}",
unique-id = "{ISI:000074160600003}"
}

93. L VejbyChristensen, LH Andersen, O Heber, D Kella, HB Pedersen, HT Schmidt and D Zajfman.
Complete branching ratios for the dissociative recombination of H2O+, H3O+, and CH3+. ASTROPHYSICAL JOURNAL 483(1, 1):531-540, 1997.
BibTeX

@article{ ISI:A1997XJ16700051,
author = "VejbyChristensen, L and Andersen, LH and Heber, O and Kella, D and Pedersen, HB and Schmidt, HT and Zajfman, D",
title = "{Complete branching ratios for the dissociative recombination of H2O+, H3O+, and CH3+}",
journal = "{ASTROPHYSICAL JOURNAL}",
year = "{1997}",
volume = "{483}",
number = "{1, 1}",
pages = "{531-540}",
month = "{JUL 1}",
abstract = "{Dissociative recombination of the polyatomic ions H2O+, H3O+, and CH3+ with electrons has been measured at the heavy-ion storage ring ASTRID. Complete branching ratios for all the possible product channels have been determined at zero relative energy using an energy-sensitive detector masked by grids with known transmissions. In the dissociative recombination of H3O+, water molecules are produced with a probability of 33\%, whereas the production of atomic oxygen is negligible. Atomic carbon is, on the other hand, produced with a branching ratio of 30\% in the dissociative recombination of CH3+. For all three molecular ions, the three-particle breakup is a major process. Relative cross sections for dissociative recombination of H3O+ and for dissociative excitation of H3O+ have been measured for relative electron energies up to 40 eV. Implications for the modeling of the chemistry of interstellar molecular clouds are discussed.}",
issn = "{0004-637X}",
unique-id = "{ISI:A1997XJ16700051}"
}

94. HT Schmidt, H Cederquist, R Schuch, L Bagge, A Kallberg, J Hilke, KG Rensfelt, V Mergel, M Achler, R Dorner, L Spielberger, O Jagutzki, H SchmidtBocking, J Ullrich, H Reich, M Unverzagt, W Schmitt and R Moshammer.
A design study for an internal gas-jet target for the heavy-ion storage ring CRYRING. HYPERFINE INTERACTIONS 108(1-3):339-354, 1997.
DOI BibTeX

@article{ ISI:A1997XE44700036,
author = "Schmidt, HT and Cederquist, H and Schuch, R and Bagge, L and Kallberg, A and Hilke, J and Rensfelt, KG and Mergel, V and Achler, M and Dorner, R and Spielberger, L and Jagutzki, O and SchmidtBocking, H and Ullrich, J and Reich, H and Unverzagt, M and Schmitt, W and Moshammer, R",
title = "{A design study for an internal gas-jet target for the heavy-ion storage ring CRYRING}",
journal = "{HYPERFINE INTERACTIONS}",
year = "{1997}",
volume = "{108}",
number = "{1-3}",
pages = "{339-354}",
note = "{2nd Euroconference on Atomic Physics with Stored Highly Charged Ions, STOCKHOLM, SWEDEN, JUN 03-07, 1996}",
organization = "{Royal Swedish Acad Sci}",
abstract = "{This paper presents the design of the internal gas-jet target, CRYJET, which is being constructed for investigations of, e.g., fast ion-atom collisions in the heavy-ion storage and cooler ring CRYRING at the Manne Siegbahn Laboratory, Stockholm University. The goal for the design work was to create an ultra-cold He target (less than or equal to 10 mK in the longitudinal direction and 0.5 mK transverse temperature) with a density of similar to 10(12) atoms/cm(3). Care was taken in order to minimize the influence from the jet on the very low background pressure in the storage ring (similar to 10(-11) mbar) The low temperature is essential for the resolution in the experiments. The high density will enable us to get sufficient luminosities for investigations of processes with cross sections down to the 10(-27) cm(2) range. The gas-jet target will be equipped with two recoil-ion-momentum spectrometers in order to extract detailed information about the collision dynamics.}",
doi = "{10.1023/A:1012635418262}",
issn = "{0304-3843}",
researcherid-numbers = "{Doerner, Reinhard/A-5340-2008}",
orcid-numbers = "{Doerner, Reinhard/0000-0002-3728-4268}",
unique-id = "{ISI:A1997XE44700036}"
}

95. LH Andersen, P Hvelplund, D Kella, PH Mokler, HB Pedersen, HT Schmidt and L VejbyChristensen.
Resonance structure in the electron-impact detachment cross section of C-2(-) caused by the formation of C-2(2-). JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS 29(17):L643-L649, 1996.
DOI BibTeX

@article{ ISI:A1996VH73900003,
author = "Andersen, LH and Hvelplund, P and Kella, D and Mokler, PH and Pedersen, HB and Schmidt, HT and VejbyChristensen, L",
title = "{Resonance structure in the electron-impact detachment cross section of C-2(-) caused by the formation of C-2(2-)}",
journal = "{JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS}",
year = "{1996}",
volume = "{29}",
number = "{17}",
pages = "{L643-L649}",
month = "{SEP 14}",
abstract = "{Electrons have been scattered on C-2(-) in the energy range from 0-35 eV. A resonance structure in the e(-) + C-2(-) --> C-2 + 2(e)(-) detachment channel was observed at an energy of about 10 eV. To explain the structure, a C-2(2-) potential curve was constructed from the isoelectronic N-2 ground-state potential curve and the repulsive Coulomb potential, and it is argued that the structure may be related to the population of a C-2(2-) state. The state is predicted to decay primarily by electron emission since a large potential barrier prevents dissociation into C- + C-.}",
doi = "{10.1088/0953-4075/29/17/003}",
issn = "{0953-4075}",
unique-id = "{ISI:A1996VH73900003}"
}

96. HT Schmidt, L VejbyChristensen, HB Pedersen, N Bjerre and LH Andersen.
Dissociative recombination for vibrationally excited H-2(+) ions: The effect of laser photodissociation on the initial vibrational distribution. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS 29(12):2485-2496, 1996.
DOI BibTeX

@article{ ISI:A1996UW06700012,
author = "Schmidt, HT and VejbyChristensen, L and Pedersen, HB and Bjerre, N and Andersen, LH",
title = "{Dissociative recombination for vibrationally excited H-2(+) ions: The effect of laser photodissociation on the initial vibrational distribution}",
journal = "{JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS}",
year = "{1996}",
volume = "{29}",
number = "{12}",
pages = "{2485-2496}",
month = "{JUN 28}",
abstract = "{We report on measurements of dissociative recombination of H-2(+) ions populated in a range of initial vibrational levels with free electrons in the energy range of 0-20 eV. A photodissociation technique was applied to modify the vibrational distribution, and the influence on the dissociative-recombination (DR) spectrum was studied. To estimate the vibrational distribution in the experiment, the results of a simple model calculation describing a part of the measured spectrum are presented. From the comparison between the experimental data and the model calculation, we conclude that when laser photodissociation is not applied, our result is consistent with a Franck-Condon vibrational distribution from the ion source. When laser photodissociation is applied, a dramatic change of the DR spectrum is observed, which is consistent with the expected effect, based on theoretical photodissociation cross sections.}",
doi = "{10.1088/0953-4075/29/12/012}",
issn = "{0953-4075}",
unique-id = "{ISI:A1996UW06700012}"
}

97. L VejbyChristensen, D Kella, D Mathur, HB Pedersen, HT Schmidt and LH Andersen.
Electron-impact detachment from negative ions. PHYSICAL REVIEW A 53(4):2371-2378, April 1996.
DOI BibTeX

@article{ ISI:A1996UE92100064,
author = "VejbyChristensen, L and Kella, D and Mathur, D and Pedersen, HB and Schmidt, HT and Andersen, LH",
title = "{Electron-impact detachment from negative ions}",
journal = "{PHYSICAL REVIEW A}",
year = "{1996}",
volume = "{53}",
number = "{4}",
pages = "{2371-2378}",
month = "{APR}",
abstract = "{Electron-impact detachment cross sections have been measured from threshold to about 30 eV for D- and O-. The purpose was to investigate the cross section near threshold and to reinvestigate earlier claims of resonances due to short-lived states of the doubly charged negative ion. Initial results for D- showed no resonances {[}L. H. Andersen, D. Mathur, H. T. Schmidt, and L. Vejby-Christensen, Phys. Rev. Lett. 74, 892 (1995)]. Here we show that there is no detectable resonance structure for O- either. The applied experimental technique is discussed in detail. Classical and semiclassical models for the detachment process are presented and compared with the data.}",
doi = "{10.1103/PhysRevA.53.2371}",
issn = "{1050-2947}",
unique-id = "{ISI:A1996UE92100064}"
}

98. LH ANDERSEN, D MATHUR, HT SCHMIDT and L VEJBYCHRISTENSEN.
ELECTRON-IMPACT DETACHMENT OF D- - NEAR-THRESHOLD BEHAVIOR AND THE NONEXISTENCE OF D2- RESONANCES. PHYSICAL REVIEW LETTERS 74(6):892-895, 1995.
DOI BibTeX

@article{ ISI:A1995QE48700016,
author = "ANDERSEN, LH and MATHUR, D and SCHMIDT, HT and VEJBYCHRISTENSEN, L",
title = "{ELECTRON-IMPACT DETACHMENT OF D- - NEAR-THRESHOLD BEHAVIOR AND THE NONEXISTENCE OF D2- RESONANCES}",
journal = "{PHYSICAL REVIEW LETTERS}",
year = "{1995}",
volume = "{74}",
number = "{6}",
pages = "{892-895}",
month = "{FEB 6}",
doi = "{10.1103/PhysRevLett.74.892}",
issn = "{0031-9007}",
unique-id = "{ISI:A1995QE48700016}"
}

99. HT SCHMIDT, P FORCK, M GRIESER, D HABS, J KENNTNER, G MIERSCH, R REPNOW, U SCHRAMM, T SCHUSSLER, D SCHWALM and A WOLF.
HIGH-PRECISION MEASUREMENT OF THE MAGNETIC-DIPOLE DECAY-RATE OF METASTABLE HELIUM-LIKE CARBON-IONS IN A STORAGE-RING. PHYSICAL REVIEW LETTERS 72(11):1616-1619, 1994.
DOI BibTeX

@article{ ISI:A1994NA49200011,
author = "SCHMIDT, HT and FORCK, P and GRIESER, M and HABS, D and KENNTNER, J and MIERSCH, G and REPNOW, R and SCHRAMM, U and SCHUSSLER, T and SCHWALM, D and WOLF, A",
title = "{HIGH-PRECISION MEASUREMENT OF THE MAGNETIC-DIPOLE DECAY-RATE OF METASTABLE HELIUM-LIKE CARBON-IONS IN A STORAGE-RING}",
journal = "{PHYSICAL REVIEW LETTERS}",
year = "{1994}",
volume = "{72}",
number = "{11}",
pages = "{1616-1619}",
month = "{MAR 14}",
abstract = "{The radiative decay rate of C4+ ions in the metastable 1s2s3S1 state has been measured at the ion storage ring TSR in Heidelberg, observing the time dependence of the dielectronic recombination rate on resonances characteristic for this metastable state. The very accurate result of 48.57+/-0.11 s-1 allows us to distinguish between different theoretical approaches. Our result is in excellent agreement with a calculation of the magnetic-dipole decay rate using nonrelativistic radial wave functions for the heliumlike carbon ion.}",
doi = "{10.1103/PhysRevLett.72.1616}",
issn = "{0031-9007}",
researcherid-numbers = "{Schramm, Ulrich/C-9393-2012}",
unique-id = "{ISI:A1994NA49200011}"
}

100. HT SCHMIDT, GY PAN and LH ANDERSEN.
DIELECTRONIC RECOMBINATION WITH DELTA-N = 0 AND DELTA-N = 1 CORE EXCITATIONS AND RADIATIVE RECOMBINATION FOR C-LIKE F3+ IONS. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS 25(14):3165-3174, 1992.
DOI BibTeX

@article{ ISI:A1992JG79800011,
author = "SCHMIDT, HT and PAN, GY and ANDERSEN, LH",
title = "{DIELECTRONIC RECOMBINATION WITH DELTA-N = 0 AND DELTA-N = 1 CORE EXCITATIONS AND RADIATIVE RECOMBINATION FOR C-LIKE F3+ IONS}",
journal = "{JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS}",
year = "{1992}",
volume = "{25}",
number = "{14}",
pages = "{3165-3174}",
month = "{JUL 28}",
abstract = "{A merged-beams technique has been used to measure the rate coefficient (nu-sigma) for radiative recombination (RR) as well as dielectronic recombination (DR) with C-like F3+ ions at relative energies up to 74 eV. The RR measurement is compared to a theory based on the hydrogenic approximation with an effective charge Z(eff). The data indicate that Z(eff) is larger than the full ionic charge. This is believed to be due to incomplete screening. DR with DELTA-n = 0 core excitations as well as DR with DELTA-n = 1 core excitations is observed. Structures associated with all three terms of the ground-state configuration of F3+ are found in our spectra, whereas no sign is seen of the metastable 1s(2)2s2p3 5S state.}",
doi = "{10.1088/0953-4075/25/14/011}",
issn = "{0953-4075}",
unique-id = "{ISI:A1992JG79800011}"
}

101. LH ANDERSEN, GY PAN, HT SCHMIDT, NR BADNELL and MS PINDZOLA.
ABSOLUTE MEASUREMENTS AND CALCULATIONS OF DIELECTRONIC RECOMBINATION WITH METASTABLE HE-LIKE N, F, AND SI IONS. PHYSICAL REVIEW A 45(11):7868-7875, 1992.
DOI BibTeX

@article{ ISI:A1992HX67700030,
author = "ANDERSEN, LH and PAN, GY and SCHMIDT, HT and BADNELL, NR and PINDZOLA, MS",
title = "{ABSOLUTE MEASUREMENTS AND CALCULATIONS OF DIELECTRONIC RECOMBINATION WITH METASTABLE HE-LIKE N, F, AND SI IONS}",
journal = "{PHYSICAL REVIEW A}",
year = "{1992}",
volume = "{45}",
number = "{11}",
pages = "{7868-7875}",
month = "{JUN 1}",
abstract = "{Measurements and calculations of the rate coefficient {[}upsilon-sigma] for dielectronic recombination associated with He-like ions of nitrogen, fluorine, and silicon are reported for electron energies between 0 and 27 eV. In this energy region, no resonances are associated with excitation of the 1s2 ground state, however, the metastable states 1s2s(1S) and 1s2s(3S) contribute with very large rate coefficients. The population of the 1s2s(3S) metastable state was determined by an independent x-ray measurement. We performed calculations in the LS-coupling and intermediate-coupling approximations for dielectronic recombination from the initial 3S and 1S states. For the 3S initial state, a comparison on an absolute scale between theory and experiment is presented. We flnd good agreement with LS-coupling calculations for N5+(3S), one exception being a structure observed below the 1S and 3P threshold. For Si12+(3S), the intermediate-coupling calculation reproduces the data fairly well. In the case of F7+(3S), we find discrepancies with both the LS- and intermediate-coupling calculations at low energy and just below the 1S and 3P thresholds. The contribution from the initial 1s2s(1S) state is important only for N5+. Here, the experimental data are in excellent agreement with the theory if the 1S metastable fraction is assumed to be about 1\%.}",
doi = "{10.1103/PhysRevA.45.7868}",
issn = "{1050-2947}",
unique-id = "{ISI:A1992HX67700030}"
}

102. LH ANDERSEN, GY PAN, HT SCHMIDT, MS PINDZOLA and NR BADNELL.
STATE-SELECTIVE MEASUREMENTS AND CALCULATIONS OF DIELECTRONIC RECOMBINATION WITH LI-LIKE N4+, F6+, AND SI11+ IONS. PHYSICAL REVIEW A 45(9):6332-6338, 1992.
DOI BibTeX

@article{ ISI:A1992HT73300026,
author = "ANDERSEN, LH and PAN, GY and SCHMIDT, HT and PINDZOLA, MS and BADNELL, NR",
title = "{STATE-SELECTIVE MEASUREMENTS AND CALCULATIONS OF DIELECTRONIC RECOMBINATION WITH LI-LIKE N4+, F6+, AND SI11+ IONS}",
journal = "{PHYSICAL REVIEW A}",
year = "{1992}",
volume = "{45}",
number = "{9}",
pages = "{6332-6338}",
month = "{MAY 1}",
abstract = "{Absolute measurements and calculations of the rate coefficient {[}nu-sigma] for dielectronic recombination associated with Li-like ions of nitrogen, fluorine, and silicon are reported. The measurements were performed with a single-pass merged-beam technique. The excitation associated with the dielectronic recombination reaction is 2s --> 2p. With the present energy resolution, we are able to distinguish between capture into low-lying resonances, which are insensitive to perturbing fields, and capture into the high Rydberg states, which are perturbed by small electric fields present in the experiment. The experimental data are compared with distorted-wave calculations that include the influence of static electric fields in the interaction region.}",
doi = "{10.1103/PhysRevA.45.6332}",
issn = "{1050-2947}",
unique-id = "{ISI:A1992HT73300026}"
}

103. LH ANDERSEN, GY PAN and HT SCHMIDT.
RADIATIVE RECOMBINATION WITH HIGHLY CHARGED SI6+ AND SI11+ IONS. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS 25(1):277-283, 1992.
DOI BibTeX

@article{ ISI:A1992HA95200029,
author = "ANDERSEN, LH and PAN, GY and SCHMIDT, HT",
title = "{RADIATIVE RECOMBINATION WITH HIGHLY CHARGED SI6+ AND SI11+ IONS}",
journal = "{JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS}",
year = "{1992}",
volume = "{25}",
number = "{1}",
pages = "{277-283}",
month = "{JAN 14}",
abstract = "{The rate coefficient  for radiative recombination between free electrons and highly charged Si6+ and Si11+ ions has been measured in the energy region from 0 to 1 eV. The experimental results were obtained with a merged-beams technique. Knowledge about the relative velocity distribution allowed a direct comparison with theory. It was found that for Li-like Si11+, the effective charge to be used in a calculation developed for bare ions is the total ion charge, Z(eff) almost-equal-to 11. This is in agreement with earlier findings for H-like ions and other Li-like ions. For O-like Si6+, the effective charge is found to be Z(eff) almost-equal-to 9. For Si6+, the measured rate coefficient is more than a factor of two larger than calculations based on the total ion charge (Z(eff) = 6). This shows evidence for significant incomplete screening in the case of Si6+.}",
doi = "{10.1088/0953-4075/25/1/029}",
issn = "{0953-4075}",
unique-id = "{ISI:A1992HA95200029}"
}

104. NR BADNELL, MS PINDZOLA, LH ANDERSEN, J BOLKO and HT SCHMIDT.
DIELECTRONIC RECOMBINATION OF LIGHT BE-LIKE AND B-LIKE IONS. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS 24(20):4441-4452, 1991.
DOI BibTeX

@article{ ISI:A1991GN16600014,
author = "BADNELL, NR and PINDZOLA, MS and ANDERSEN, LH and BOLKO, J and SCHMIDT, HT",
title = "{DIELECTRONIC RECOMBINATION OF LIGHT BE-LIKE AND B-LIKE IONS}",
journal = "{JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS}",
year = "{1991}",
volume = "{24}",
number = "{20}",
pages = "{4441-4452}",
month = "{OCT 28}",
abstract = "{Dielectronic recombination cross sections from the ground and metastable states of the Be-like ions C2+, O4+ and F5+, and the B-like ions O3+ and F4+, have been calculated and compared with experimental results obtained by a merged-beams technique. The comparison of theory and experiment is complicated by the presence of weak electric fields in the interaction region. However, we can qualitatively explain the main features of our experimental results. In particular, for Be-like ions we find evidence of a large contribution from the initial 2s2p 3P metastable state recombining into an Auger metastable final state.}",
doi = "{10.1088/0953-4075/24/20/014}",
issn = "{0953-4075}",
unique-id = "{ISI:A1991GN16600014}"
}