Change search
Refine search result
1 - 23 of 23
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1. Bernigaud, Virgile
    et al.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Haag, Nicole
    Stockholm University, Faculty of Science, Department of Physics.
    Holm, Anne I. S.
    Stockholm University, Faculty of Science, Department of Physics.
    Huber, Bernd A.
    Hvelplund, Preben
    Kadhane, Umesh
    Larsen, Mikkel Koefod
    Manil, Bruno
    Nielsen, Steen Bröndsted
    Panja, Subhasis
    Ptasinska, Sylwia
    Rangama, Jimmy
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Schmidt, Henning T.
    Stockholm University, Faculty of Science, Department of Physics.
    Streletskii, Alexey V.
    Stöchkel, Kristian
    Worm, Esben S.
    Zettergren, Henning
    Stockholm University, Faculty of Science, Department of Physics.
    Electron capture-induced dissociation of AK dipeptide dications: Influence of ion velocity, crown-ether complexation and collision gas2008In: International Journal of Mass Spectrometry, ISSN 1387-3806, E-ISSN 1873-2798, Vol. 276, no 2-3, p. 77-81Article in journal (Refereed)
    Abstract [en]

    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–Cα 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–Cα bond breakage is more or less constant.

  • 2.
    Bäckström, Erik
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Hanstorp, D.
    Hole, Odd Magnar
    Stockholm University, Faculty of Science, Department of Physics.
    Kaminska, Magdalena
    Stockholm University, Faculty of Science, Department of Physics. Jan Kochanowski University, Poland.
    Nascimento, Rodrigo F.
    Stockholm University, Faculty of Science, Department of Physics.
    Blom, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Björkhage, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Källberg, Anders
    Stockholm University, Faculty of Science, Department of Physics.
    Löfgren, Patrik
    Stockholm University, Faculty of Science, Department of Physics.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Rosén, Stefan
    Stockholm University, Faculty of Science, Department of Physics.
    Simonsson, Ansgar
    Stockholm University, Faculty of Science, Department of Physics.
    Thomas, Richard D.
    Stockholm University, Faculty of Science, Department of Physics.
    Mannervik, Sven
    Stockholm University, Faculty of Science, Department of Physics.
    Schmidt, Henning T.
    Stockholm University, Faculty of Science, Department of Physics.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Storing keV negative ions for an hour: The lifetime of the metastable 2P1/2 level in 32S−2015In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 114, no 14, article id 143003Article in journal (Refereed)
    Abstract [en]

    We use a novel electrostatic ion storage ring to measure the radiative lifetime of the upper level in the 3p 5  P 2  o 1/2 →3p 5  P 2  o 3/2   spontaneous radiative decay in S −  32   to be 503±54  sec . This is by orders of magnitude the longest lifetime ever measured in a negatively charged ion. Cryogenic cooling of the storage ring gives a residual-gas pressure of a few times 10 −14   mbar at 13 K and storage of 10 keV sulfur anions for more than an hour. Our experimental results differ by 1.3σ  from the only available theoretical prediction.

  • 3.
    Chartkunchand, Kiattichart C.
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Kaminska, Magdalena
    Stockholm University, Faculty of Science, Department of Physics. Jan Kochanowski University, Poland.
    Anderson, Emma K.
    Stockholm University, Faculty of Science, Department of Physics.
    Kristiansson, M. K.
    Eklund, Gustav
    Stockholm University, Faculty of Science, Department of Physics.
    Hole, Odd Magnar
    Stockholm University, Faculty of Science, Department of Physics.
    Nascimento, Rodrigo F.
    Stockholm University, Faculty of Science, Department of Physics. Centro Federal de Educação Tecnológica Celso Suckow da Fonseca, Brazil.
    Blom, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Björkhage, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Källberg, Anders
    Stockholm University, Faculty of Science, Department of Physics.
    Löfgren, Patrik
    Stockholm University, Faculty of Science, Department of Physics.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Rosén, Stefan
    Stockholm University, Faculty of Science, Department of Physics.
    Simonsson, Ansgar
    Stockholm University, Faculty of Science, Department of Physics.
    Thomas, Richard D.
    Stockholm University, Faculty of Science, Department of Physics.
    Mannervik, Sven
    Stockholm University, Faculty of Science, Department of Physics.
    Davis, V. T.
    Neill, P. A.
    Thompson, J. S.
    Hanstorp, D.
    Zettergren, Henning
    Stockholm University, Faculty of Science, Department of Physics.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Schmidt, Henning T.
    Stockholm University, Faculty of Science, Department of Physics.
    Radiative lifetimes of the bound excited states of Pt-2016In: Physical Review A, ISSN 2469-9926, Vol. 94, no 3, article id 032501Article in journal (Refereed)
    Abstract [en]

    The intrinsic radiative lifetimes of the 5d(10)6s(2)S(1/2) and 5d(9)6s(2) D-2(3/2) bound excited states in the platinum anion Pt- have been studied at cryogenic temperatures at the Double ElectroStatic Ion Ring Experiment (DESIREE) facility at Stockholm University. The intrinsic lifetime of the higher-lying 5d(10)6s S-2(1/2) state was measured to be 2.54 +/- 0.10 s, while only a lifetime in the range of 50-200 ms could be estimated for the 5d(9)6s(2) D-2(3/2) fine-structure level. The storage lifetime of the Pt- ion beam was measured to be a little over 15 min at a ring temperature of 13 K. The present study reports the lifetime of an atomic negative ion in an excited bound state with an electron configuration different from that of the ground state.

  • 4.
    Chartkunchand, Kiattichart C.
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Stockett, Mark H.
    Stockholm University, Faculty of Science, Department of Physics.
    Anderson, Emma K.
    Stockholm University, Faculty of Science, Department of Physics.
    Eklund, Gustav
    Stockholm University, Faculty of Science, Department of Physics.
    Kristiansson, Moa K.
    Stockholm University, Faculty of Science, Department of Physics.
    Kamińska, Magdalena
    Stockholm University, Faculty of Science, Department of Physics. Jan Kochanowski University, Poland.
    de Ruette, Nathalie
    Stockholm University, Faculty of Science, Department of Physics.
    Blom, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Björkhage, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Källberg, Anders
    Stockholm University, Faculty of Science, Department of Physics.
    Löfgren, Patrik
    Stockholm University, Faculty of Science, Department of Physics.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Rosén, Stefan
    Stockholm University, Faculty of Science, Department of Physics.
    Simonsson, Ansgar
    Stockholm University, Faculty of Science, Department of Physics.
    Zettergren, Henning
    Stockholm University, Faculty of Science, Department of Physics.
    Schmidt, Henning T.
    Stockholm University, Faculty of Science, Department of Physics.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Dianion diagnostics in DESIREE: High-sensitivity detection of C-n(2-) from a sputter ion source2018In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 89, no 3, article id 033112Article in journal (Refereed)
    Abstract [en]

    A sputter ion source with a solid graphite target has been used to produce dianions with a focus on carbon cluster dianions, C-n(2-), with n = 7-24. Singly and doubly charged anions from the source were accelerated together to kinetic energies of 10 keV per atomic unit of charge and injected into one of the cryogenic (13 K) ion-beam storage rings of the Double ElectroStatic Ion Ring Experiment facility at Stockholm University. Spontaneous decay of internally hot C-n(2-) dianions injected into the ring yielded C-n(2-) anions with kinetic energies of 20 keV, which were counted with a microchannel plate detector. Mass spectra produced by scanning the magnetic field of a 90 degrees analyzing magnet on the ion injection line reflect the production of internally hot C-7(2-) - C-24(2-) dianions with lifetimes in the range of tens of microseconds to milliseconds. In spite of the high sensitivity of this method, no conclusive evidence of C-6(2-) was found while there was a clear C-7(2-) signal with the expected isotopic distribution. This is consistent with earlier experimental studies and with theoretical predictions. An upper limit is deduced for a C-6(2-) signal that is two orders-of-magnitude smaller than that for C-7(2-). In addition, CnO2- and CnCu2- dianions were detected.

  • 5.
    Fischer, D.
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Gudmundsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics.
    Berenyi, Zoltan
    Stockholm University, Faculty of Science, Department of Physics.
    Haag, Nicole
    Stockholm University, Faculty of Science, Department of Physics.
    Johansson, Henrik A. B.
    Stockholm University, Faculty of Science, Department of Physics.
    Misra, Deepankar
    Stockholm University, Faculty of Science, Department of Physics.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Kallberg, A.
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Simonsson, Ansgar
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Stochkel, K.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Schmidt, H. T.
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Importance of Thomas single-electron transfer in fast p-He collisions2010In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 81, no 1, p. 12714-Article in journal (Refereed)
    Abstract [en]

    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.

  • 6.
    Gatchell, Michael
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Schmidt, Henning T.
    Stockholm University, Faculty of Science, Department of Physics.
    Alexander, John D.
    Stockholm University, Faculty of Science, Department of Physics.
    Andler, Guillermo
    Stockholm University, Faculty of Science, Department of Physics.
    Björkhage, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Blom, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Brännholm, Lars
    Stockholm University, Faculty of Science, Department of Physics.
    Bäckström, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Chen, Tao
    Stockholm University, Faculty of Science, Department of Physics.
    Geppert, Wolf
    Stockholm University, Faculty of Science, Department of Physics.
    Halldén, Per
    Stockholm University, Faculty of Science, Department of Physics.
    Hanstorp, Dag
    Hellberg, Fredrik
    Stockholm University, Faculty of Science, Department of Physics.
    Källberg, Anders
    Stockholm University, Faculty of Science, Department of Physics.
    Larsson, Mats
    Stockholm University, Faculty of Science, Department of Physics.
    Leontein, Sven
    Stockholm University, Faculty of Science, Department of Physics.
    Liljeby, Leif
    Stockholm University, Faculty of Science, Department of Physics.
    Löfgren, Patrik
    Stockholm University, Faculty of Science, Department of Physics.
    Mannervik, Sven
    Stockholm University, Faculty of Science, Department of Physics.
    Paal, Andras
    Stockholm University, Faculty of Science, Department of Physics.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Rensfelt, Karl-Gunnar
    Stockholm University, Faculty of Science, Department of Physics.
    Rosén, Stefan
    Stockholm University, Faculty of Science, Department of Physics.
    Seitz, Fabian
    Stockholm University, Faculty of Science, Department of Physics.
    Simonsson, Ansgar
    Stockholm University, Faculty of Science, Department of Physics.
    Stockett, Mark H.
    Stockholm University, Faculty of Science, Department of Physics.
    Thomas, Richard D.
    Stockholm University, Faculty of Science, Department of Physics.
    Zettergren, Henning
    Stockholm University, Faculty of Science, Department of Physics.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    First results from the Double ElectroStatic Ion-Ring ExpEriment, DESIREE2014In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 488, p. 092003-Article in journal (Refereed)
    Abstract [en]

    We have stored the first beams in one of the rings of the double electrostatic ion-storage ring, DESIREE at cryogenic and at room temperature conditions. At cryogenic operations the following parameters are found. Temperature; T= 13K, pressure; p <10(-13) mbar, initial number of stored ions; N > 10(7) and storage lifetime of a C-2(-) beam; tau = 450 S.

  • 7.
    Gatchell, Michael
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Schmidt, Henning T.
    Stockholm University, Faculty of Science, Department of Physics.
    Thomas, Richard D.
    Stockholm University, Faculty of Science, Department of Physics.
    Rosén, Stefan
    Stockholm University, Faculty of Science, Department of Physics.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Löfgren, Patrik
    Stockholm University, Faculty of Science, Department of Physics.
    Brännholm, Lars
    Stockholm University, Faculty of Science, Department of Physics.
    Blom, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Björkhage, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Bäckström, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Alexander, John D.
    Stockholm University, Faculty of Science, Department of Physics.
    Leontein, Sven
    Stockholm University, Faculty of Science, Department of Physics.
    Hanstorp, D.
    Zettergren, Henning
    Stockholm University, Faculty of Science, Department of Physics.
    Liljeby, Leif
    Stockholm University, Faculty of Science, Department of Physics.
    Källberg, Anders
    Stockholm University, Faculty of Science, Department of Physics.
    Simonsson, Ansgar
    Stockholm University, Faculty of Science, Department of Physics.
    Hellberg, Fredrik
    Stockholm University, Faculty of Science, Department of Physics.
    Mannervik, Sven
    Stockholm University, Faculty of Science, Department of Physics.
    Larsson, Mats
    Stockholm University, Faculty of Science, Department of Physics.
    Geppert, Wolf D.
    Stockholm University, Faculty of Science, Department of Physics.
    Rensfelt, Karl-Gunnar
    Stockholm University, Faculty of Science, Department of Physics.
    Danared, Håkan
    Stockholm University, Faculty of Science, Department of Physics. European Spallation Source, Sweden.
    Paál, Andras
    Stockholm University, Faculty of Science, Department of Physics.
    Masuda, Masaharu
    Stockholm University, Faculty of Science, Department of Physics.
    Halldén, Per
    Stockholm University, Faculty of Science, Department of Physics.
    Andler, Guillermo
    Stockholm University, Faculty of Science, Department of Physics.
    Stockett, Mark H.
    Stockholm University, Faculty of Science, Department of Physics.
    Chen, Tao
    Stockholm University, Faculty of Science, Department of Physics.
    Källersjö, Gunnar
    Stockholm University, Faculty of Science, Department of Physics.
    Weimer, Jan
    Stockholm University, Faculty of Science, Department of Physics.
    Hansen, K.
    Hartman, H.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Commissioning of the DESIREE storage rings - a new facility for cold ion-ion collisions2014In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 488, p. 012040-Article in journal (Refereed)
    Abstract [en]

    We report on the ongoing commissioning of the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. Beams of atomic carbon anions (C-) and smaller carbon anion molecules (C-2(-), C-3(-), C-4(-) etc.) have been produced in a sputter ion source, accelerated to 10 keV or 20 keV, and stored successfully in the two electrostatic rings. The rings are enclosed in a common vacuum chamber cooled to below 13 Kelvin. The DESIREE facility allows for studies of internally relaxed single isolated atomic, molecular and cluster ions and for collision experiments between cat-and anions down to very low center-of-mass collision energies (meV scale). The total thermal load of the vacuum chamber at this temperature is measured to be 32 W. The decay rates of stored ion beams have two components: a non-exponential component caused by the space charge of the beam itself which dominates at early times and an exponential term from the neutralization of the beam in collisions with residual gas at later times. The residual gas limited storage lifetime of carbon anions in the symmetric ring is over seven minutes while the 1/e lifetime in the asymmetric ring is measured to be about 30 seconds. Although we aim to improve the storage in the second ring, the number of stored ions are now sufficient for many merged beams experiments with positive and negative ions requiring milliseconds to seconds ion storage.

  • 8.
    Gudmundsson, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Fischer, D.
    Stockholm University, Faculty of Science, Department of Physics.
    Haag, N.
    Stockholm University, Faculty of Science, Department of Physics.
    Johansson, H. A. B.
    Stockholm University, Faculty of Science, Department of Physics.
    Misra, Deepankar
    Stockholm University, Faculty of Science, Department of Physics.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Schmidt-Boecking, H.
    Schuch, Reinhold
    Stockholm University, Faculty of Science, Department of Physics.
    Schoeffler, M.
    Stochkel, K.
    Schmidt, Henning T.
    Stockholm University, Faculty of Science, Department of Physics.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Angular scattering in fast ion-atom electron transfer collisions: projectile wave diffraction and Thomas mechanisms2010In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 43, no 18, p. 185209-Article in journal (Refereed)
    Abstract [en]

    We report experimental angular differential cross sections for double-electron capture in He2+ + 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.

  • 9.
    Kamińska, Magdalena
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Jan Kochanowski University, Poland.
    Davis, V. T.
    Hole, Odd Magnar
    Stockholm University, Faculty of Science, Department of Physics.
    Nascimento, Rodrigo F.
    Stockholm University, Faculty of Science, Department of Physics. Centro Federal de Educação Tecnológica Celso Suckow da Fonseca, Brazil.
    Chartkunchand, Kiattichart C.
    Stockholm University, Faculty of Science, Department of Physics. University of Nevada, USA.
    Blom, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Björkhage, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Källberg, Anders
    Stockholm University, Faculty of Science, Department of Physics.
    Löfgren, Patrik
    Stockholm University, Faculty of Science, Department of Physics.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Rosén, Stefan
    Stockholm University, Faculty of Science, Department of Physics.
    Simonsson, Ansgar
    Stockholm University, Faculty of Science, Department of Physics.
    Thomas, Richard D.
    Stockholm University, Faculty of Science, Department of Physics.
    Mannervik, Sven
    Stockholm University, Faculty of Science, Department of Physics.
    Neill, P. A.
    Thompson, J. S.
    Schmidt, Henning T.
    Stockholm University, Faculty of Science, Department of Physics.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Hanstorp, D.
    Lifetime of the bound excited level in Ni-2016In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 93, no 1, article id 012512Article in journal (Refereed)
    Abstract [en]

    The intrinsic lifetime of the upper level in the bound-bound 3d(9) 4s(2) D-2(3/2) -> 3d(9) 4s(2) D-2(5/2) radiative transition in Ni- was measured to be 15.1 +/- 0.4 s. The experiment was performed at cryogenic temperatures in one of the ion-beam storage rings of the Double ElectroStatic Ion Ring ExpEriment facility at Stockholm University. The storage lifetime of the Ni- ion beam was measured to be close to 5 min at a ring temperature of 13 K.

  • 10.
    Misra, Deepankar
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Schmidt, Henning Thordal
    Stockholm University, Faculty of Science, Department of Physics.
    Gudmundsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics.
    Fischer, Daniel
    Max-Planck Institut, Heidelberg.
    Haag, Nicole
    Stockholm University, Faculty of Science, Department of Physics.
    Johansson, Henrik A B
    Stockholm University, Faculty of Science, Department of Physics.
    Källberg, Anders
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Najjari, B
    Max-Planck Institut, Heidelberg.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Schuch, Reinhold
    Stockholm University, Faculty of Science, Department of Physics.
    Schöffler, Marcus
    Frankfurt University.
    Simonsson, Ansgar
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Voitkiv, A B
    Max-Planck Institut, Heidelberg.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Two-Center Double-Capture Interference in Fast He2++H2 Collisions2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 102, no 15, p. 153201-Article in journal (Refereed)
    Abstract [en]

    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) He^{2+}-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.

  • 11.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Ions in cold electrostatic storage devices2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    We have constructed a compact purely electrostatic ion-beam trap, ConeTrap, which we have mounted inside a double-walled vacuum chamber. In the inner vacuum chamber, we can obtain ultra-high vacuum (UHV) conditions and reach thermal equilibrium at well controlled temperatures down to 10 K. The chamber was constructed partly with the purpose of making high-precision measurements in ConeTrap, but also as a test-chamber for testing components (such as the detector-assembly tested and described in this thesis and paper III) to be used in the DESIREE (Double ElectroStatic Ion Ring ExpEriment) facility. The latter is a double electrostatic ion storage-ring being constructed at Stockholm University, in which the conditions are meant to mimic the environment in the interstellar medium. The interaction between two oppositely charged ions at very low relative velocities (controlled collision energies down to 10 meV) may then be studied in a section of the storage device where the two ion beams merge.

    The lifetime of loosely bound electronic systems, for example He-, is, at room temperature (and even at much lower temperatures), significantly affected by photons from blackbody radiation from the experimental device and its surroundings. The cryogenic temperature and low pressure obtained in the test chamber have made it possible to use ConeTrap to make the first correction-free lifetime measurement of the long-lived J=5/2 fine-structure level of the metastable 1s2s2p 4Po state of He-. Under the assumption of a statistical population of the fine-structure levels, at the time when the ions are created, we have also deduced the lifetimes of the short-lived J=1/2 and J=3/2 fine-structure levels. Furthermore, we have used ConeTrap to measure the pressure dependent storage lifetimes of He+ and Ar+ ions over wide ranges of temperatures and pressures, and we have thus been able to store positive ions with storage lifetimes of tens of seconds.

  • 12.
    Reinhed, Peter
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Orbán, Andrea
    Stockholm University, Faculty of Science, Department of Physics.
    Rosén, Stefan
    Stockholm University, Faculty of Science, Department of Physics.
    Thomas, Richard
    Stockholm University, Faculty of Science, Department of Physics.
    Kashperka, Iryna
    Stockholm University, Faculty of Science, Department of Physics.
    Johansson, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Misra, Deepankar
    Stockholm University, Faculty of Science, Department of Physics.
    Fardi, Afshin
    Brännholm, Lars
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Björkhage, Mikael
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Schmidt, Henning
    Stockholm University, Faculty of Science, Department of Physics.
    Cryogenic keV ion-beam storage in ConeTrap - a tool for ion-temperature control2010In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 621, no 1-3, p. 83-90Article in journal (Refereed)
    Abstract [en]

    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 1.3·10-10 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 [Phys. Rev. Lett. 103, 213002(2009)].

  • 13.
    Reinhed, Peter
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Orbán, Andrea
    Stockholm University, Faculty of Science, Department of Physics.
    Werner, Josefina
    Stockholm University, Faculty of Science, Department of Physics.
    Rosén, Stefan
    Stockholm University, Faculty of Science, Department of Physics.
    Thomas, Richard D.
    Stockholm University, Faculty of Science, Department of Physics.
    Kashperka, Iryna
    Stockholm University, Faculty of Science, Department of Physics.
    Johansson, Henrik A. B.
    Stockholm University, Faculty of Science, Department of Physics.
    Misra, Deepankar
    Stockholm University, Faculty of Science, Department of Physics.
    Brännholm, Lars
    Stockholm University, Faculty of Science, Department of Physics, The Manne Siegbahn Laboratory.
    Björkhage, Mikael
    Stockholm University, Faculty of Science, Department of Physics, The Manne Siegbahn Laboratory.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Schmidt, Henning T.
    Stockholm University, Faculty of Science, Department of Physics.
    Precision lifetime measurements of He- in a cryogenic electrostatic ion-beam trap2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 103, no 21, p. 213002-Article in journal (Refereed)
    Abstract [en]

    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 black-body radiation. We report the first correction free measurements of the lifetimes of the 1s2s2p 4PoJ state of 4He- and the high precision result 359.0±0.7 μs for the J=5/2 level. The lifetimes for the J=3/2 and J=1/2 levels are determined to be 12.3±0.5 and 7.8±1.0 μs, respectively.

  • 14.
    Rosén, Stefan
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Schmidt, Henning
    Stockholm University, Faculty of Science, Department of Physics.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Fischer, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Thomas, Richard
    Stockholm University, Faculty of Science, Department of Physics.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Liljeby, Leif
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Bagge, Lars
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Leontein, Sven
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Blom, Mikael
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Operating a triple stack microchannel plate-phosphor assembly for single particle counting in the 12-300 K temperature range2007In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 78, no 11, p. 113301-Article in journal (Refereed)
    Abstract [en]

    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 2.1×103 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 μs when the temperature was decreased from 300 to 100 K while the decay time then decreased and reached a value of 5 μs at 12 K. The pulse height distribution from the PMT was measured between300 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.

  • 15.
    Schmidt, Henning T.
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Thomas, Richard D.
    Stockholm University, Faculty of Science, Department of Physics.
    Gatchell, Michael
    Stockholm University, Faculty of Science, Department of Physics.
    Rosén, Stefan
    Stockholm University, Faculty of Science, Department of Physics.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Löfgren, Patrik
    Stockholm University, Faculty of Science, Department of Physics.
    Brännholm, Lars
    Stockholm University, Faculty of Science, Department of Physics.
    Blom, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Björkhage, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Bäckström, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Alexander, John D.
    Stockholm University, Faculty of Science, Department of Physics.
    Leontein, Sven
    Stockholm University, Faculty of Science, Department of Physics.
    Hanstorp, D.
    Zettergren, Henning
    Stockholm University, Faculty of Science, Department of Physics.
    Liljeby, Leif
    Stockholm University, Faculty of Science, Department of Physics.
    Källberg, Anders
    Stockholm University, Faculty of Science, Department of Physics.
    Simonsson, Ansgar
    Stockholm University, Faculty of Science, Department of Physics.
    Hellberg, Fredrik
    Stockholm University, Faculty of Science, Department of Physics.
    Mannervik, Sven
    Stockholm University, Faculty of Science, Department of Physics.
    Larsson, Mats
    Stockholm University, Faculty of Science, Department of Physics.
    Geppert, Wolf D.
    Stockholm University, Faculty of Science, Department of Physics.
    Rensfelt, Karl-Gunnar
    Stockholm University, Faculty of Science, Department of Physics.
    Danared, Håkan
    Stockholm University, Faculty of Science, Department of Physics.
    Paal, A.
    Stockholm University, Faculty of Science, Department of Physics.
    Masuda, Masaharu
    Stockholm University, Faculty of Science, Department of Physics.
    Hallden, Per
    Stockholm University, Faculty of Science, Department of Physics.
    Andler, Guillermo
    Stockholm University, Faculty of Science, Department of Physics.
    Stockett, Mark H.
    Stockholm University, Faculty of Science, Department of Physics.
    Chen, Tao
    Stockholm University, Faculty of Science, Department of Physics.
    Källersjö, Gunnar
    Stockholm University, Faculty of Science, Department of Physics.
    Weimer, Jan
    Stockholm University, Faculty of Science, Department of Physics.
    Hansen, K.
    Hartman, H.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    First storage of ion beams in the Double Electrostatic Ion-Ring Experiment: DESIREE2013In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 84, no 5, p. 055115-Article in journal (Refereed)
    Abstract [en]

    We report on the first storage of ion beams in the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. We have produced beams of atomic carbon anions and small carbon anion molecules (C-n(-), n = 1, 2, 3, 4) in a sputter ion source. The ion beams were accelerated to 10 keV kinetic energy and stored in an electrostatic ion storage ring enclosed in a vacuum chamber at 13 K. For 10 keV C-2(-) molecular anions we measure the residual-gas limited beam storage lifetime to be 448 s +/- 18 s with two independent detector systems. Using the measured storage lifetimes we estimate that the residual gas pressure is in the 10(-14) mbar range. When high current ion beams are injected, the number of stored particles does not follow a single exponential decay law as would be expected for stored particles lost solely due to electron detachment in collision with the residual-gas. Instead, we observe a faster initial decay rate, which we ascribe to the effect of the space charge of the ion beam on the storage capacity.

  • 16.
    Schmidt, Henning
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Fischer, Daniel
    Stockholm University, Faculty of Science, Department of Physics.
    Berenyi, Zoltan
    Stockholm University, Faculty of Science, Department of Physics.
    Cocke, Charles Lewis
    Gudmundsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics.
    Haag, Nicole
    Stockholm University, Faculty of Science, Department of Physics.
    Johansson, Henrik A. B.
    Stockholm University, Faculty of Science, Department of Physics.
    Källberg, Anders
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Levin, Sergey B.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Sassenberg, Ulf
    Stockholm University, Faculty of Science, Department of Physics.
    Schuch, Reinhold
    Stockholm University, Faculty of Science, Department of Physics.
    Simonsson, Ansgar
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Stöchkel, Kristian
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Evidence of Wave-Particle Duality for Single Fast Hydrogen Atoms2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 8, p. 083201-Article in journal (Refereed)
    Abstract [en]

    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+ + H2 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.

  • 17.
    Schmidt, Henning
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Johansson, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Thomas, Richard
    Stockholm University, Faculty of Science, Department of Physics.
    Geppert, Wolf
    Stockholm University, Faculty of Science, Department of Physics.
    Haag, Nicole
    Stockholm University, Faculty of Science, Department of Physics.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Rosén, Stefan
    Stockholm University, Faculty of Science, Department of Physics.
    Larsson, Mats
    Stockholm University, Faculty of Science, Department of Physics.
    Danared, Håkan
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Rensfelt, K.-G
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Liljeby, Leif
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Bagge, Lars
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Björkhage, Mikael
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Blom, Mikael
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Löfgren, Patrik
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Källberg, Anders
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Simonsson, Ansgar
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Paál, Andras
    Stockholm University, Faculty of Science, The Manne Siegbahn Laboratory .
    Zettergren, Henning
    Stockholm University, Faculty of Science, Department of Physics.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    DESIREE as a new tool for interstellar ion chemistry2008In: International Journal of Astrobiology, ISSN 1473-5504, E-ISSN 1475-3006, Vol. 7, no 3-4, p. 205-208Article in journal (Refereed)
    Abstract [en]

    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.

  • 18.
    Schmidt, Henning T.
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Eklund, Gustav
    Stockholm University, Faculty of Science, Department of Physics.
    Chartkunchand, Kiattichart C.
    Stockholm University, Faculty of Science, Department of Physics.
    Anderson, Emma K.
    Stockholm University, Faculty of Science, Department of Physics.
    Kamińska, Magdalena
    Stockholm University, Faculty of Science, Department of Physics. Jan Kochanowski University, Poland.
    de Ruette, Nathalie
    Stockholm University, Faculty of Science, Department of Physics.
    Thomas, Richard D.
    Stockholm University, Faculty of Science, Department of Physics.
    Kristiansson, Moa K.
    Stockholm University, Faculty of Science, Department of Physics.
    Gatchell, Michael
    Stockholm University, Faculty of Science, Department of Physics.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Rosen, Stefan
    Stockholm University, Faculty of Science, Department of Physics.
    Simonsson, Ansgar
    Stockholm University, Faculty of Science, Department of Physics.
    Källberg, Anders
    Stockholm University, Faculty of Science, Department of Physics.
    Löfgren, Patrik
    Stockholm University, Faculty of Science, Department of Physics.
    Mannervik, Sven
    Stockholm University, Faculty of Science, Department of Physics.
    Zettergren, Henning
    Stockholm University, Faculty of Science, Department of Physics.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Rotationally Cold OH- Ions in the Cryogenic Electrostatic Ion-Beam Storage Ring DESIREE2017In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 119, no 7, article id 073001Article in journal (Refereed)
    Abstract [en]

    We apply near-threshold laser photodetachment to characterize the rotational quantum level distribution of OH- ions stored in the cryogenic ion-beam storage ring DESIREE at Stockholm University. We find that the stored ions relax to a rotational temperature of 13.4 +/- 0.2 K with 94.9 +/- 0.3% of the ions in the rotational ground state. This is consistent with the storage ring temperature of 13.5 +/- 0.5 K as measured with eight silicon diodes but in contrast to all earlier studies in cryogenic traps and rings where the rotational temperatures were always much higher than those of the storage devices at their lowest temperatures. Furthermore, we actively modify the rotational distribution through selective photodetachment to produce an OH- beam where 99.1 +/- 0.1% of approximately one million stored ions are in the J = 0 rotational ground state. We measure the intrinsic lifetime of the J = 1 rotational level to be 145 +/- 28 s.

  • 19.
    Thomas, Richard D.
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Schmidt, Henning T.
    Stockholm University, Faculty of Science, Department of Physics.
    Andler, Guillermo
    Stockholm University, Faculty of Science, Department of Physics.
    Björkhage, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Blom, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Brännholm, Lars
    Stockholm University, Faculty of Science, Department of Physics.
    Bäckstrom, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Danared, Håkan
    Stockholm University, Faculty of Science, Department of Physics.
    Das, Susanta
    Stockholm University, Faculty of Science, Department of Physics.
    Haag, Nicole
    Stockholm University, Faculty of Science, Department of Physics.
    Halldén, Per
    Stockholm University, Faculty of Science, Department of Physics.
    Hellberg, Fredrik
    Stockholm University, Faculty of Science, Department of Physics.
    Holm, Anne I. S.
    Stockholm University, Faculty of Science, Department of Physics.
    Johansson, H. A. B.
    Stockholm University, Faculty of Science, Department of Physics.
    Källberg, Anders
    Stockholm University, Faculty of Science, Department of Physics.
    Källersjö, Gunnar
    Stockholm University, Faculty of Science, Department of Physics.
    Larsson, Mats
    Stockholm University, Faculty of Science, Department of Physics.
    Leontein, Sven
    Stockholm University, Faculty of Science, Department of Physics.
    Liljeby, Leif
    Stockholm University, Faculty of Science, Department of Physics.
    Löfgren, Patrik
    Stockholm University, Faculty of Science, Department of Physics.
    Malm, Bo
    Stockholm University, Faculty of Science, Department of Physics.
    Mannervik, Sven
    Stockholm University, Faculty of Science, Department of Physics.
    Masuda, Masaharu
    Stockholm University, Faculty of Science, Department of Physics.
    Misra, Deepankar
    Stockholm University, Faculty of Science, Department of Physics.
    Orban, A.
    Stockholm University, Faculty of Science, Department of Physics.
    Paál, Andras
    Stockholm University, Faculty of Science, Department of Physics.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Rensfelt, Karl-Gunnar
    Stockholm University, Faculty of Science, Department of Physics.
    Rosén, Stefan
    Stockholm University, Faculty of Science, Department of Physics.
    Schmidt, K.
    Stockholm University, Faculty of Science, Department of Physics.
    Seitz, Fabian
    Stockholm University, Faculty of Science, Department of Physics.
    Simonsson, Ansgar
    Stockholm University, Faculty of Science, Department of Physics.
    Weimer, Jan
    Stockholm University, Faculty of Science, Department of Physics.
    Zettergren, Henning
    Stockholm University, Faculty of Science, Department of Physics.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    The double electrostatic ion ring experiment: A unique cryogenic electrostatic storage ring for merged ion-beams studies2011In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 82, no 6, p. 065112-Article in journal (Refereed)
    Abstract [en]

    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.

  • 20.
    Thomas, Richard D.
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Schmidt, Henning T.
    Stockholm University, Faculty of Science, Department of Physics.
    Gatchell, Michael
    Stockholm University, Faculty of Science, Department of Physics.
    Rosén, Sara
    Stockholm University, Faculty of Science, Department of Physics.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Löfgren, Patrik
    Stockholm University, Faculty of Science, Department of Physics.
    Brännholm, Lars
    Stockholm University, Faculty of Science, Department of Physics.
    Blom, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Björkhage, Mikael
    Stockholm University, Faculty of Science, Department of Physics.
    Bäckström, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Alexander, John D.
    Stockholm University, Faculty of Science, Department of Physics.
    Leontein, Sven
    Stockholm University, Faculty of Science, Department of Physics.
    Hanstorp, D.
    Zettergren, Henning
    Stockholm University, Faculty of Science, Department of Physics.
    Kaminska, Magdalena
    Stockholm University, Faculty of Science, Department of Physics.
    Nascimento, Rodrigo
    Stockholm University, Faculty of Science, Department of Physics.
    Liljeby, Leif
    Stockholm University, Faculty of Science, Department of Physics.
    Källberg, Anders
    Stockholm University, Faculty of Science, Department of Physics.
    Simonsson, Ansgar
    Stockholm University, Faculty of Science, Department of Physics.
    Hellberg, Fredrik
    Stockholm University, Faculty of Science, Department of Physics.
    Mannervik, Sven
    Stockholm University, Faculty of Science, Department of Physics.
    Larsson, Mats
    Stockholm University, Faculty of Science, Department of Physics.
    Geppert, Wolf D.
    Stockholm University, Faculty of Science, Department of Physics.
    Rensfelt, Karl-Gunnar
    Stockholm University, Faculty of Science, Department of Physics.
    Paál, Andras
    Stockholm University, Faculty of Science, Department of Physics.
    Masuda, Masaharu
    Stockholm University, Faculty of Science, Department of Physics.
    Halldén, Per
    Stockholm University, Faculty of Science, Department of Physics.
    Andler, Guillermo
    Stockholm University, Faculty of Science, Department of Physics.
    Stockett, Mark H.
    Stockholm University, Faculty of Science, Department of Physics.
    Chen, Tao
    Stockholm University, Faculty of Science, Department of Physics.
    Källersjö, Gunnar
    Stockholm University, Faculty of Science, Department of Physics.
    Weimer, Jan
    Stockholm University, Faculty of Science, Department of Physics.
    Hansen, K.
    Hartman, H.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    DESIREE: Physics with cold stored ion beams2015In: DR2013: Ninth international conference on dissociative recombination: theory, experiment, and applications, 2015, Vol. 84, article id 01004Conference paper (Refereed)
    Abstract [en]

    Here we will briefly describe the commissioning of the Double ElectroStatic Ion Ring ExpEriment (DESIREE) facility at Stockholm University, Sweden. This device uses purely electrostatic focussing and deflection elements and allows ion beams of opposite charge to be confined under extreme high vacuum and cryogenic conditions in separate rings and then merged over a common straight section. This apparatus allows for studies of interactions between cations and anions at very low and well-defined centre-of-mass energies (down to a few meV) and at very low internal temperatures (down to a few K).

  • 21.
    Zettergren, Henning
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Adoui, Lamri
    Bernigaud, Virgile
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Haag, Nicole
    Stockholm University, Faculty of Science, Department of Physics.
    Holm, Anne I. S.
    Stockholm University, Faculty of Science, Department of Physics.
    Huber, Bernd A.
    Hvelplund, Preben
    Johansson, Henrik A. B.
    Stockholm University, Faculty of Science, Department of Physics.
    Kadhane, Umesh
    Larsen, Mikkel Kofoed
    Liu, Bo
    Manil, Bruno
    Bröndsted Nielsen, Steen
    Panja, Subhasis
    Rangama, Jimmy
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Schmidt, Henning T.
    Stockholm University, Faculty of Science, Department of Physics.
    Stöchkel, Kristian
    Electron-Capture-Induced Dissociation of Microsolvated Di- and > Tripeptide Monocations: Elucidation of Fragmentation Channels from > Measurements of Negative Ions2009In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 10, no 9-10, p. 1619-1623Article in journal (Refereed)
    Abstract [en]

    The branching ratio between ammonia loss and NCα bond cleavage of singly charged microsolvated peptides after electron capture from cesium depends on the solvent molecule attached. Density functional calculations reveal that for [GA+H]+(CE) (G=glycine, A=alanine, CE=crown ether), the singly occupied molecular orbital of the neutral radical is located mainly on the amide group (see picture).

    The results from an experimental study of bare and microsolvated peptide monocations in high-energy collisions with cesium vapor are reported. Neutral radicals form after electron capture from cesium, which decay by H loss, NH3 loss, or NCα 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=glycine, A=alanine), the branching ratio between NH3 loss and NCα bond cleavage is found to strongly depend on the molecule attached (H2O, CH3CN, CH3OH, and 18-crown-6 ether (CE)). Addition of H2O and CH3OH increases this ratio whereas CH3CN and CE decrease it. For protonated AAA ([AAA+H]+), a similar effect is observed with methanol, while the ratio between the z1 and z2 fragment peaks remains unchanged for the bare and microsolvated species. Density functional theory calculations reveal that in the case of [GA+H]+(CE), the singly occupied molecular orbital is located mainly on the amide group in accordance with the experimental results.

  • 22.
    Zettergren, Henning
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Rangama, J.
    Huber, B. A.
    Støchkel, K.
    Schmidt, H. T.
    Cederquist, H.
    Jensen, J.
    Tomita, S.
    Nielsen, S. B.
    Hvelplund, P.
    Manil, B.
    Fragmentation and ionization of C70 and C60 by slow ions of intermediate charge2006In: European Physical Journal D: Atomic, Molecular and Optical Physics, ISSN 1434-6060, E-ISSN 1434-6079, Vol. 38, no 2, p. 299-306Article in journal (Refereed)
    Abstract [en]

    We have measured total and coincident (with outgoing charge-state analyzed projectiles) ionization and fragmentation spectra of C60 and C70 following collisions with Xe4+ and Kr4+ at v = 0.06 a.u. Intact positive fullerene ions in charge states up to five (C605+ and C705+) are produced with both projectiles and for Kr4++C70 collisions we even observe a small C706+ peak. The C60/70-2m3+ (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 C3+-C11+ 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++C60 and Kr4++C60 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.

  • 23.
    Zettergren, Henning
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Reinhed, Peter
    Stockholm University, Faculty of Science, Department of Physics.
    Støchkel, K
    Stockholm University, Faculty of Science, Department of Physics.
    Schmidt, Henning
    Stockholm University, Faculty of Science, Department of Physics.
    Cederquist, Henrik
    Stockholm University, Faculty of Science, Department of Physics.
    Jensen, J
    Tomita, S
    B. Nielsen, S
    Hvelplund, P
    Manil, B
    Rangama, J
    Huber, B.A
    Fragmentation and ionization of C70 and C60 by slow ions of intermediate charge2006In: European Physical Journal D: Atomic, Molecular and Optical Physics, ISSN 1434-6060, E-ISSN 1434-6079, The European physical journal D Atomic, molecular and optical physics, Vol. 38, no 2, p. 299-306Article in journal (Refereed)
    Abstract [en]

      

     

     

     

     

     

        

     

     

     

     

     

     

     

      

     

    We have measured total and coincident (with outgoing charge-state analyzed projectiles) ionization

    and fragmentation spectra of C

     

    60 and C70 following collisions with Xe4+ and Kr4+ at v = 0.

    06 a.u.

    Intact positive fullerene ions in charge states up to five (C

     

    5+

    60

     

    and C

    5+

    70

     

    ) are produced with both projectiles

    and for Kr

     

    4++C70 collisions we even observe a small C

    6+

    70

     

    peak. The C

    3+

    60

     

    /702m (m

    = 1–7) intensity distributions

    are predominantly associated with the stabilization of three electrons on the projectile (

     

    s

    = 3) and

    are significantly different for Xe

     

    4+- 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 Xe

     

    4++C60 and Kr4++C60

    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.

1 - 23 of 23
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf