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  • 1. Abu-samha, M
    et al.
    Borve, K. J.
    Winkler, M
    Harnes, J
    Saethre, L. J.
    Lindblad, A
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Bergersen, H
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Björneholm, O
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Svensson, S
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Öhrwall, G
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    The local structure of small water clusters: imprints on the core-level photoelectron spectrum2009In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 42, no 5, p. 055201-Article in journal (Refereed)
    Abstract [en]

    We report on an O 1s photoelectron-spectroscopy study of small neutral water clusters produced by adiabatic expansion. The photoelectron spectra were acquired under two different experimental conditions. At intermediate resolution, the cluster signal was characterized by a very broad O 1s peak with a flat top. In the second set of measurements, resolution was significantly increased at the cost of lower count rates. The cluster signal was now partly resolved into a bimodal structure. Extensive theoretical calculations were undertaken to facilitate an interpretation of the spectrum. These results suggest that the bimodal feature may be ascribed to ionization of water molecules in different hydrogen-bonding configurations, more specifically, molecules characterized by donation of either one or both hydrogen atoms in H-bonding.

  • 2.
    Andersson, T.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Zhang, C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Mikkela, M-H
    Oulu Univ, Dept Phys Sci, Box 3000, FI-90014 Oulu, Finland..
    Jankala, K.
    Oulu Univ, Dept Phys Sci, Box 3000, FI-90014 Oulu, Finland..
    Anin, D.
    Oulu Univ, Dept Phys Sci, Box 3000, FI-90014 Oulu, Finland..
    Urpelainen, S.
    Oulu Univ, Dept Phys Sci, Box 3000, FI-90014 Oulu, Finland..
    Huttula, M.
    Oulu Univ, Dept Phys Sci, Box 3000, FI-90014 Oulu, Finland..
    Tchaplyguine, M.
    Lund Univ, Max Lab, Box 118, SE-22363 Lund, Sweden..
    Electronic structure transformation in small bare Au clusters as seen by x-ray photoelectron spectroscopy2017In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 50, no 1, article id 015102Article in journal (Refereed)
    Abstract [en]

    Free bare gold clusters in the size range from few tens to few hundred atoms (<= 1 nm dimensions) have been produced in a beam, and the size-dependent development of their full valence band including the 5d and 6s parts has been mapped 'on the fly' by synchrotron-based photoelectron spectroscopy. The Au 4f core level has been also probed, and the cluster-specific Au 4f ionization energies have been used to estimate the cluster size. The recorded in the present work valence spectra of the small clusters are compared with the spectra of the large clusters (N similar to 10(3)) created by us using a magnetron-based gas aggregation source. The comparison shows a substantially narrower 5d valence band and the decrease in its splitting for gold clusters in the size range of few hundred atoms and below. Our DFT calculations involving the pseudopotential method show that the 5d band width of the ground state increases with the cluster size and by the size N = 20 becomes comparable with the experimental width of the valence photoelectron spectrum. Similar to the earlier observations on supported clusters we interpret our experimental and theoretical results as due to the undercoordination of a large fraction of atoms in the clusters with N similar to 10(2) and below. The consequences of such electronic structure of small gold clusters are discussed in connection with their specific physical and chemical properties related to nanoplasmonics and nanocatalysis.

  • 3.
    Angelova Hamberg, Gergana
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Dissociative recombination of rare gas hydride ions: I. NeH+2005In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455Article in journal (Refereed)
  • 4.
    Angelova Hamberg, Gergana
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    The Dissociative Recombination of CF3+2004In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455Article in journal (Refereed)
  • 5.
    Bao, Zhuo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Fink, Reinhold F.
    Travnikova, Oksana
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Céolin, Denis
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Piancastelli, Maria Novella
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Detailed Theoretical and Experimental Description of Normal Auger Decay in O22008In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 41, no 12, p. 125101-Article in journal (Refereed)
    Abstract [en]

    The normal Auger electron spectrum of the O-2 molecule is assigned in detail on the basis of ab initio valence configuration interaction (CI) wavefunctions. Potential energy curves of the ground state, the core-ionized states and the doubly charged final states are calculated and Auger decay rates are obtained with the one-centre approximation. Using the lifetime vibrational interference method, band shapes are obtained for all contributions to the Auger spectrum. The calculated Auger electron spectrum allows us to identify all features observed experimentally. Significant differences to previous assignments are reported. A quantitative simulation of the spectrum is given on the basis of a curve-fitting procedure, in which the energetic positions and intensities of the theoretical bands were optimized. Besides providing a basis for a refined analysis of the spectrum, the fit allows us to assess the accuracy of the calculation. As expected for this level of theory, the absolute accuracy of the valence CI energies is found to be about 0.3 eV. The inherent error of the one-centre transition rates is less than 5% of the most intense transition in the spectrum. The frequently questioned one-centre Auger transition rates are shown to be rather appropriate if applied with reasonable wavefunctions and if the vibrational band structure of the molecular spectrum is properly taken into account.

  • 6.
    Berggren, P.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Stegeby, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Voronin, A.
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Impact of the strong force on the Coulombic decay of a hydrogen-antihydrogen molecule2008In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 41, no 15, p. 155202-Article in journal (Refereed)
    Abstract [en]

    The lifetime of the meta-stable hydrogen-antihydrogen molecule in various vibrational states is calculated. The partial lifetime with respect to the proton-antiproton annihilation is obtained from complex eigenvalues which arise upon inclusion of the strong force in the adiabatic formulation of the molecular decay problem. We study the influence of the strong force, which causes annihilation, on the transition probability for decay via Coulombic rearrangement to protonium and positronium.

  • 7. Bomme, C.
    et al.
    Guillemin, R.
    Marin, T.
    Journel, L.
    Marchenko, T.
    Trcera, N.
    Kushawaha, R. K.
    Piancastelli, M. N.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Simon, M.
    Stener, M.
    Decleva, P.
    Molecular-frame photoelectron angular distribution imaging studies of OCS S1s photoionization2012In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 45, no 19, p. 194005-Article in journal (Refereed)
  • 8. Bomme, C.
    et al.
    Guillemin, R.
    Sheinerman, S.
    Marin, T.
    Journel, L.
    Marchenko, T.
    Kushawaha, R. K.
    Trcera, N.
    Piancastelli, Maria Novella
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Simon, M.
    Post-collision interaction manifestation in molecular systems probed by photoelectron-molecular ion coincidences2013In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 46, no 21, p. 215101-Article in journal (Refereed)
    Abstract [en]

    S1s photoionization in carbonyl sulfide (OCS), followed by multiple Auger decay is investigated both experimentally and theoretically, by means of photoelectron-ion coincidences. A strong influence of post-collision interaction is observed in the energy shift and the distortion of the photoelectron spectra. The magnitude of this effect depends on the total charge of the ionic fragments, i.e., on the number of electrons emitted during the decay of the inner vacancy. A satisfactory agreement is found between experiment and theory, which allows us to estimate the lifetimes of the various two-hole states of the intermediate OCS2+ ion.

  • 9. Burmeister, F
    et al.
    Andersson, L M
    Ohrwall, G
    Richter, T
    Zimmermann, P
    Godehusen, K
    Martins, M
    Karlsson, H O
    Sorensen, S L
    Bjorneholm, O
    Feifel, R
    Wiesner, K
    Goscinski, O
    Karlsson, L
    Svensson, S
    Yencha, A J
    A study of the inner-valence ionization region in HCl and DCl2004In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 37, no 6, p. 1173-1183Article in journal (Refereed)
    Abstract [en]

    An in-depth photoionization study of the inner-valence electrons in HCl and DCl has been performed using synchrotron radiation. A series of photoelectron spectra of HCl were obtained at a resolution of 23 meV over the binding energy range 25-30.5 eV at various excitation energies and at two different electron collection angles relative to the plane of polarization of the undulator radiation. In addition, photoelectron spectra of DCl were recorded at two different excitation energies. These spectra were compared directly with the threshold photoelectron spectra of HCl and DCl that were recorded previously under similar resolution conditions (similar to30 meV). This comparative study reveals new information on the nature of the numerous band systems observed in this binding energy region. In addition, we present the experimental confirmation of the theoretical prediction given by Andersson et al (2001 Phys. Rev. A 65 012705) that a vibrational progression showing interference structure would appear in the main inner-valence ionization band in the photoelectron spectrum of DCl at a resolution of 10 meV.

  • 10. Cryan, J P
    et al.
    Glownia, J M
    Andreasson, Jakob
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Belkacem, A
    Berrah, N
    Blaga, C I
    Bostedt, C
    Bozek, J
    Cherepkov, N A
    DiMauro, L F
    Fang, L
    Gessner, O
    Guhr, M
    Hajdu, Janos
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Hertlein, M P
    Hoener, M
    Kornilov, O
    Marangos, J P
    March, A M
    McFarland, B K
    Merdji, H
    Messerschmidt, M
    Petrović, V S
    Raman, C
    Ray, D
    Reis, D A
    Semenov, S K
    Trigo, M
    White, J L
    White, W
    Young, L
    Bucksbaum, P H
    Coffee, R N
    Molecular frame Auger electron energy spectrum from N22012In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 45, no 5, p. 055601-Article in journal (Refereed)
    Abstract [en]

    Here we present the first angle-resolved, non-resonant (normal) Auger spectra for impulsively aligned nitrogen molecules. We have measured the angular pattern of Auger electron emission following K -shell photoionization by 1.1 keV photons from the Linac Coherent Light Source (LCLS). Using strong-field-induced molecular alignment to make molecular frame measurements is equally effective for both repulsive and quasi-bound final states. The capability to resolve Auger emission angular distributions in the molecular frame of reference provides a new tool for spectral assignments in congested Auger electron spectra that takes advantage of the symmetries of the final diction states. Based on our experimental results and theoretical predictions, we propose the assignment of the spectral features in the Auger electron spectrum.

  • 11. Decleva, P
    et al.
    Fronzoni, G
    Kivimaeki, A
    Ruiz, J. Alvarez
    Svensson, S
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Shake-up transitions in S 2p, S 2s and F 1s photoionization of the SF6 molecule2009In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 42, no 5, p. 055102-Article in journal (Refereed)
    Abstract [en]

    Shake-up transitions occurring upon core photoionization in the SF6 molecule have been studied experimentally and theoretically. The S 2p, S 2s and F 1s shake-up satellite photoelectron spectra were measured using A1 Ka radiation at 1487 eV photon energy. They have been interpreted with the aid of ab initio configuration interaction calculations in the sudden-limit approximation. For the S 2p spectrum, conjugate shake-up transitions were also calculated. Clear evidence of conjugate processes is observed in the S 2p shake-up spectrum measured at 230 eV photon energy. The experimental and theoretical S 2p and S 2s shake-up spectra show very similar structures mainly due to orbital relaxation involving S 3s and 3p participation. For the calculation of the F 1s shake-up spectrum, the symmetry lowering of the molecule in the final states was considered, resulting in a good agreement with the experiment.

  • 12. Decleva, P.
    et al.
    Stener, M.
    Holland, D. M. P.
    Potts, A. W.
    Karlsson, L.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Perfluoro effects in the occupied and virtual valence orbitals of hexafluorobenzene2007In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 40, no 14, p. 2939-2959Article in journal (Refereed)
    Abstract [en]

    The complete valence shell photoelectron spectrum of hexafluorobenzene has been recorded with synchrotron radiation and the observed structure has been interpreted using ab initio ionization energies and relative spectral intensities. The theoretical predictions for the single-hole ionic states due to outer valence shell ionization agree satisfactorily with the experimental results. Ionization from the inner valence, essential F 2s, orbitals is strongly influenced by many-body effects and the intensity is spread amongst numerous satellites. Photoelectron angular distributions and branching ratios have been determined both experimentally and theoretically, and demonstrate that shape resonances affect the valence shell photoionization dynamics. Some of the shape resonances have been associated with virtual valence orbitals. An assessment of the perfluoro effect on the occupied and virtual valence orbitals of hexafluorobenzene has been carried out by comparing the present results for C6F6 with similar data for C6H6.

  • 13.
    Decleva, Piero
    et al.
    Univ Trieste, Dipartimento Sci Chim & Farmaceut, I-34127 Trieste, Italy.;CNR, Ist Officina Mat, I-34149 Trieste, Italy..
    Toffoli, Daniele
    Univ Trieste, Dipartimento Sci Chim & Farmaceut, I-34127 Trieste, Italy.;CNR, Ist Officina Mat, I-34149 Trieste, Italy..
    Kushawaha, Rajesh Kumar
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, UMR 7614,Lab Chim Phys Mat & Rayonnement, F-75005 Paris, France..
    MacDonald, Michael
    Canadian Light Source Inc, 44 Innovat Blvd, Saskatoon, SK S7N 2V3, Canada..
    Piancastelli, Maria Novella
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. UPMC Univ Paris 06, Sorbonne Univ, CNRS, UMR 7614,Lab Chim Phys Mat & Rayonnement, F-75005 Paris, France..
    Simon, Marc
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, UMR 7614,Lab Chim Phys Mat & Rayonnement, F-75005 Paris, France..
    Zuin, Lucia
    Canadian Light Source Inc, 44 Innovat Blvd, Saskatoon, SK S7N 2V3, Canada..
    Interference effects in photoelectron asymmetry parameter (beta) trends of C 2s(-1) states of ethyne, ethene and ethane2016In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 49, no 23, article id 235102Article in journal (Refereed)
    Abstract [en]

    Photoelectron asymmetry parameters (beta) of the gerade and ungerade C 2s(-1) derived states of ethyne, ethene and ethane as a function of photon energy have been calculated and experimentally measured, to extend the search of interference effects on angular distributions to polyatomic molecules. The calculations cover the electron energy range from 0 to 1100 eV while the experimental measurements cover the electron energy range from 30 to 220 eV. Clear oscillations are interpreted in terms of interference of the photoelectron wave emitted from the two possible C 2s centres, or equivalently from the gerade and ungerade states associated with them. This is a microscopic analog of Young's double-slit experiment. The effect is however quite small and requires very high experimental accuracy to be detected. It is best evidenced in the behaviour of beta difference between the two channels. The connection between beta trends and structural parameters shows the expected inverse correlation between oscillation period and distance between the carbon atoms, but do not simply parallel the analogous behaviour found in cross sections.

  • 14.
    Dubernet, M. L.
    et al.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Antony, B. K.
    Indian Sch Mines, Dept Appl Phys, Dhanbad 826004, Bihar, India..
    Ba, Y. A.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Babikov, Yu L.
    Russian Acad Sci, Inst Atmospher Opt, Zuev Sq 1, Tomsk 634021, Russia.;Tomsk State Univ, Tomsk 634050, Russia..
    Bartschat, K.
    Drake Univ, Dept Phys & Astron, Des Moines, IA 50311 USA..
    Boudon, V.
    Univ Bourgogne Franche Comte, CNRS, UMR 6303, Lab Interdisciplinaire Carnot Bourgogne, 9 Ave Alain Savary,BP 47 870, F-21078 Dijon, France..
    Braams, B. J.
    IAEA, Vienna Int Ctr, Div Phys & Chem Sci, Nucl Data Sect, A-1400 Vienna, Austria..
    Chung, H-K
    IAEA, Vienna Int Ctr, Div Phys & Chem Sci, Nucl Data Sect, A-1400 Vienna, Austria..
    Daniel, F.
    Univ Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France..
    Delahaye, F.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Del Zanna, G.
    Ctr Math Sci, DAMTP, Wilberforce Rd, Cambridge CB3 0WA, England..
    de Urquijo, J.
    Univ Nacl Autonoma Mexico, Inst Ciencias Fis, POB 48-3, Cuernavaca 62251, Morelos, Mexico..
    Dimitrijevic, M. S.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France.;Astron Observ, Volgina 7, Belgrade 11060, Serbia..
    Domaracka, A.
    UCN, ENSICAEN, CNRS, CIMAP,UMR 6252,CEA, Bd Henri Becquerel,BP 5133, F-14070 Caen 5, France..
    Doronin, M.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Drouin, B. J.
    CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA..
    Endres, C. P.
    Max Planck Inst Extraterr Phys, Giessenbachstr, D-85748 Garching, Germany..
    Fazliev, A. Z.
    Russian Acad Sci, Inst Atmospher Opt, Zuev Sq 1, Tomsk 634021, Russia..
    Gagarin, S. V.
    Russian Fed Nucl Ctr All Russian Inst Tech Phys R, Snezhinsk, Russia..
    Gordon, I. E.
    Harvard Smithsonian Ctr Astrophys, Atom & Mol Phys Div, MS50,60 Garden St, Cambridge, MA 02138 USA..
    Gratier, P.
    Univ Bordeaux, LAB, UMR 5804, F-33270 Florac, France.;CNRS, LAB, UMR 5804, F-33270 Florac, France..
    Heiter, Ulrike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Hill, C.
    UCL, Dept Phys & Astron, Mortimer St, London WC1E 6BT, England..
    Jevremovic, D.
    Astron Observ, Volgina 7, Belgrade 11060, Serbia..
    Joblin, C.
    Univ Toulouse, UPS OMP, CNRS, Inst Rech Astrophys & Planetol, 9 Av Colonel Roche, F-31028 Toulouse 4, France..
    Kasprzak, A.
    Observ Paris, SRCV, 61 Av Denfert Rochereau, F-75014 Paris, France..
    Krishnakumar, E.
    Tata Inst Fundamental Res, Dept Nucl & Atom Phys, Homi Bhabha Rd, Bombay 400005, Maharashtra, India..
    Leto, G.
    INAF Osservatorio Astrofis Catania, Via S Sofia 78, I-95123 Catania, Italy..
    Loboda, P. A.
    Russian Fed Nucl Ctr All Russian Inst Tech Phys R, Snezhinsk, Russia.;Natl Res Nucl Univ, Moscow Engn Phys Inst MEPhI, Moscow, Russia..
    Louge, T.
    Univ Toulouse, UPS OMP, CNRS, Inst Rech Astrophys & Planetol, 9 Av Colonel Roche, F-31028 Toulouse 4, France..
    Maclot, S.
    UCN, ENSICAEN, CNRS, CIMAP,UMR 6252,CEA, Bd Henri Becquerel,BP 5133, F-14070 Caen 5, France.;Univ Caen Normandie, Esplanade Paix, CS 14032, F-14032 Caen 5, France..
    Marinkovic, B. P.
    Univ Belgrade, Inst Phys Belgrade, POB 57, Belgrade 11001, Serbia..
    Markwick, A.
    Univ Manchester, Sch Phys & Astron, Jodrell Bank Ctr Astrophys, Oxford Rd, Manchester M13 9PL, Lancs, England..
    Marquart, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Mason, H. E.
    Ctr Math Sci, DAMTP, Wilberforce Rd, Cambridge CB3 0WA, England..
    Mason, N. J.
    Open Univ, Dept Phys Sci, Walton Hall, Milton Keynes MK7 6AA, Bucks, England..
    Mendoza, C.
    IVIC, Ctr Fis, POB 20632, Caracas 1020A, Venezuela..
    Mihajlov, A. A.
    Univ Belgrade, Inst Phys Belgrade, POB 57, Belgrade 11001, Serbia..
    Millar, T. J.
    Queens Univ Belfast, Sch Math & Phys, Univ Rd, Belfast BT7 1NN, Antrim, North Ireland..
    Moreau, N.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Mulas, G.
    Univ Toulouse, UPS OMP, CNRS, Inst Rech Astrophys & Planetol, 9 Av Colonel Roche, F-31028 Toulouse 4, France.;Osservatorio Astron Cagliari, Ist Nazl AstroFis, Via Sci 5, I-09047 Selargius, CA, Italy..
    Pakhomov, Yu
    RAS, Inst Astron, Pyatnitskaya 48, Moscow 119017, Russia..
    Palmeri, P.
    Univ Mons, Phys Atom & Astrophys, B-7000 Mons, Belgium..
    Pancheshnyi, S.
    ABB Corp Res, Segelhofstr 1K, CH-5405 Baden, Switzerland..
    Perevalov, V. I.
    Russian Acad Sci, Inst Atmospher Opt, Zuev Sq 1, Tomsk 634021, Russia..
    Piskunov, Nikolai
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Postler, J.
    Univ Innsbruck, Inst Ion Phys & Appl Phys, Technikerstr 25-3, A-6020 Innsbruck, Austria..
    Quinet, P.
    Univ Mons, Phys Atom & Astrophys, B-7000 Mons, Belgium.;Univ Liege, IPNAS, B-4000 Liege, Belgium..
    Quintas-Sanchez, E.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Ralchenko, Yu
    NIST, Atom Spect Grp, Gaithersburg, MD 20899 USA..
    Rhee, Y-J
    Korea Atom Energy Res Inst, Nucl Data Ctr, Taejon 305353, South Korea..
    Rixon, G.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Rothman, L. S.
    Harvard Smithsonian Ctr Astrophys, Atom & Mol Phys Div, MS50,60 Garden St, Cambridge, MA 02138 USA..
    Roueff, E.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Ryabchikova, T.
    RAS, Inst Astron, Pyatnitskaya 48, Moscow 119017, Russia..
    Sahal-Brechot, S.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Scheier, P.
    Univ Innsbruck, Inst Ion Phys & Appl Phys, Technikerstr 25-3, A-6020 Innsbruck, Austria..
    Schlemmer, S.
    Univ Cologne, Inst Phys 1, zulpicher Str 77, D-50937 Kln, Germany..
    Schmitt, B.
    Univ Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France..
    Stempels, Eric H. C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Tashkun, S.
    Russian Acad Sci, Inst Atmospher Opt, Zuev Sq 1, Tomsk 634021, Russia..
    Tennyson, J.
    UCL, Dept Phys & Astron, Mortimer St, London WC1E 6BT, England..
    Tyuterev, Vl G.
    Univ Reims, GSMA, UMR CNRS 7331, Reims, France..
    Vujcic, V.
    Astron Observ, Volgina 7, Belgrade 11060, Serbia.;Univ Belgrade, Fac Org Sci, Jove Ilica 33, Belgrade 11000, Serbia..
    Wakelam, V.
    Univ Bordeaux, LAB, UMR 5804, F-33270 Florac, France.;CNRS, LAB, UMR 5804, F-33270 Florac, France..
    Walton, N. A.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England..
    Zatsarinny, O.
    Drake Univ, Dept Phys & Astron, Des Moines, IA 50311 USA..
    Zeippen, C. J.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    Zwoelf, C. M.
    Univ Paris 06, Univ Sorbonne, CNRS, LERMA,Observ Paris,PSL Res Univ, 5 Pl Janssen, F-92190 Meudon, France..
    The virtual atomic and molecular data centre (VAMDC) consortium2016In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 49, no 7, article id 074003Article in journal (Refereed)
    Abstract [en]

    The Virtual Atomic and Molecular Data Centre (VAMDC) Consortium is a worldwide consortium which federates atomic and molecular databases through an e-science infrastructure and an organisation to support this activity. About 90% of the inter-connected databases handle data that are used for the interpretation of astronomical spectra and for modelling in many fields of astrophysics. Recently the VAMDC Consortium has connected databases from the radiation damage and the plasma communities, as well as promoting the publication of data from Indian institutes. This paper describes how the VAMDC Consortium is organised for the optimal distribution of atomic and molecular data for scientific research. It is noted that the VAMDC Consortium strongly advocates that authors of research papers using data cite the original experimental and theoretical papers as well as the relevant databases.

  • 15.
    Eland, J. H. D.
    et al.
    Univ Oxford, Dept Chem, Phys & Theoret Chem Lab, Oxford OX1 3QZ, England.;Univ Gothenburg, Dept Phys, SE-41296 Gothenburg, Sweden..
    Slater, C.
    Univ Oxford, Dept Chem, Phys & Theoret Chem Lab, Oxford OX1 3QZ, England.;Univ Gothenburg, Dept Phys, SE-41296 Gothenburg, Sweden..
    Zagorodskikh, Sergey
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics. Univ Gothenburg, Dept Phys, SE-41296 Gothenburg, Sweden..
    Singh, R.
    Univ Gothenburg, Dept Phys, SE-41296 Gothenburg, Sweden..
    Andersson, J.
    Univ Gothenburg, Dept Phys, SE-41296 Gothenburg, Sweden..
    Hult-Roos, A.
    Univ Gothenburg, Dept Phys, SE-41296 Gothenburg, Sweden..
    Lauer, A.
    Univ Oxford, Dept Chem, Phys & Theoret Chem Lab, Oxford OX1 3QZ, England..
    Squibb, R. J.
    Univ Gothenburg, Dept Phys, SE-41296 Gothenburg, Sweden..
    Feifel, R.
    Univ Gothenburg, Dept Phys, SE-41296 Gothenburg, Sweden..
    Ion charge-resolved branching in decay of inner shell holes in Xe up to 1200eV2015In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 48, no 20, article id 205001Article in journal (Refereed)
    Abstract [en]

    Using a new multi-electron multi-ion coincidence apparatus and soft x-ray synchrotron radiation we have determined branching ratios to final Xen+ states with 2 < n < 9 from the 4d(-1), 4p(-1), 4s(-1), 3d(-1) and 3p(-1) Xe+ hole states. The coincident electron spectra give information on the Auger cascade pathways. We show that by judicious choice of coincident electrons, almost pure single charge states of the final ions can be selected.

  • 16.
    Fink, Reinhold
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Eschner, Annika
    Magnuson, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Hjelte, Ingela
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Miron, Catalin
    Bässler, Margit
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Piancastelli, Maria Novella
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Sorensen, Stacey
    Specific production of very long-lived core-excited sulfur atoms by 2p(-1)sigma* excitation of the OCS molecule followed by ultrafast dissociation2006In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 39, no 12, p. L269-L275Article in journal (Refereed)
    Abstract [en]

    A core-excited sulfur state with a lifetime almost one order of magnitude longer than in molecular 2p core-hole states is selectively produced by ultrafast dissociation of S 2p -> sigma* excited OCS. Clear evidence for this is provided by strong atomic peaks (20% of the total intensity) in x-ray fluorescence but very weak ones (2%) in the corresponding resonant Auger spectrum. Corroborating the assignment of the spectra, ab initio calculations explain the enhanced lifetime: the Auger decay of the produced D-3(3) (2p(5)3p(5)) sulfur state is strongly decreased as it contradicts a newly derived propensity rule of the L2,3MM Auger decay.

  • 17.
    Froelich, Piotr
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry.
    Jonsell, Svante
    Kharchenko, Vasili
    Sadeghpour, Hossein
    Dalgarno, Alex
    On the Bose-Einstein Condensation of Exotic Atoms2006In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 39, no 18, p. 3889-3895Article in journal (Refereed)
    Abstract [en]

    The scattering length for hydrogenic atoms with variable lepton mass, ranging from H to p mu, is calculated. The non-trivial sensitivity of the scattering length to non-adiabatic effects is investigated using the coupled-channel approach. The physical conditions for the Bose-Einstein condensation of exotic atoms are expressed in terms of this scattering length, which for the p mu atoms interacting via (3)Sigma(+)(u) potentials, is calculated to be 1.13 x 10(-2) au. The critical temperature for condensing the p mu atoms is estimated to be 0.5 K at a density of 2.2 x 10(20) cm(-3). Under these conditions the phonon velocity in the condensate is 2.2 m s(-1) and the coherence length is nearly 5 mu m.

  • 18.
    Fukuzawa, H.
    et al.
    Tohoku Univ, Inst Multidisciplinary Res Adv Mat, Sendai, Miyagi 9808577, Japan.;RIKEN SPring 8 Ctr, Kouto 1-1-1, Sayo, Hyogo 6795148, Japan..
    Tachibana, T.
    Tohoku Univ, Inst Multidisciplinary Res Adv Mat, Sendai, Miyagi 9808577, Japan..
    Motomura, K.
    Tohoku Univ, Inst Multidisciplinary Res Adv Mat, Sendai, Miyagi 9808577, Japan..
    Xu, W. Q.
    Tohoku Univ, Inst Multidisciplinary Res Adv Mat, Sendai, Miyagi 9808577, Japan.;Bengbu Univ, Dept Math & Phys, Bengbu 233030, Anhui, Peoples R China..
    Nagaya, K.
    RIKEN SPring 8 Ctr, Kouto 1-1-1, Sayo, Hyogo 6795148, Japan.;Kyoto Univ, Dept Phys, Kyoto 6068502, Japan..
    Wada, S.
    RIKEN SPring 8 Ctr, Kouto 1-1-1, Sayo, Hyogo 6795148, Japan.;Hiroshima Univ, Dept Phys Sci, Higashihiroshima 7398526, Japan..
    Johnsson, P.
    Lund Univ, Dept Phys, POB 118, S-22100 Lund, Sweden..
    Siano, M.
    Univ London Imperial Coll Sci Technol & Med, Blackett Lab, Prince Consort Rd, London SW7 2AZ, England..
    Mondal, S.
    Tohoku Univ, Inst Multidisciplinary Res Adv Mat, Sendai, Miyagi 9808577, Japan..
    Ito, Y.
    Tohoku Univ, Inst Multidisciplinary Res Adv Mat, Sendai, Miyagi 9808577, Japan..
    Kimura, M.
    Tohoku Univ, Inst Multidisciplinary Res Adv Mat, Sendai, Miyagi 9808577, Japan..
    Sakai, T.
    Kyoto Univ, Dept Phys, Kyoto 6068502, Japan..
    Matsunami, K.
    Kyoto Univ, Dept Phys, Kyoto 6068502, Japan..
    Hayashita, H.
    Hiroshima Univ, Dept Phys Sci, Higashihiroshima 7398526, Japan..
    Kajikawa, J.
    Hiroshima Univ, Dept Phys Sci, Higashihiroshima 7398526, Japan..
    Liu, X-J
    LOrme des Merisiers, Synchrotron SOLEIL, BP 48, FR-91192 Gif Sur Yvette, France.;Beihang Univ, Sch Phys & Nucl Energy Engn, Beijing 100191, Peoples R China..
    Robert, E.
    LOrme des Merisiers, Synchrotron SOLEIL, BP 48, FR-91192 Gif Sur Yvette, France..
    Miron, C.
    LOrme des Merisiers, Synchrotron SOLEIL, BP 48, FR-91192 Gif Sur Yvette, France.;Horia Hulubei Natl Inst Phys & Nucl Engn, ELI NP, 30 Reactorului St, RO-077125 Magurele, Jud Ilfov, Romania..
    Feifel, Raimund
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Univ Gothenburg, Dept Phys, SE-41296 Gothenburg, Sweden..
    Marangos, J. P.
    Univ London Imperial Coll Sci Technol & Med, Blackett Lab, Prince Consort Rd, London SW7 2AZ, England..
    Tono, K.
    Japan Synchrotron Radiat Res Inst JASRI, Kouto 1-1-1, Sayo, Hyogo 6795198, Japan..
    Inubushi, Y.
    RIKEN SPring 8 Ctr, Kouto 1-1-1, Sayo, Hyogo 6795148, Japan..
    Yabashi, M.
    RIKEN SPring 8 Ctr, Kouto 1-1-1, Sayo, Hyogo 6795148, Japan..
    Yao, M.
    Kyoto Univ, Dept Phys, Kyoto 6068502, Japan..
    Ueda, K.
    Tohoku Univ, Inst Multidisciplinary Res Adv Mat, Sendai, Miyagi 9808577, Japan.;RIKEN SPring 8 Ctr, Kouto 1-1-1, Sayo, Hyogo 6795148, Japan..
    Electron spectroscopy of rare-gas clusters irradiated by x-ray free-electron laser pulses from SACLA2016In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 49, no 3, article id 034004Article in journal (Refereed)
    Abstract [en]

    We have measured electron energy spectra and asymmetry parameters of Ar clusters and Xe clusters illuminated by intense x-rays at 5 and 5.5 keV. A velocity map imaging spectrometer was developed for this purpose and employed at an x-ray free-electron laser facility, SACLA in Japan. The cluster size dependence and the peak fluence dependence of the electron spectra and asymmetry parameters are discussed.

  • 19. Guillemin, Renaud
    et al.
    Stolte, Wayne C.
    Piancastelli, Maria Novella
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Lindle, Dennis W.
    Photofragmentation of BF3 on B and F K-shell excitation by partial ion yield spectroscopy2010In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 43, no 21, p. 215205-Article in journal (Refereed)
    Abstract [en]

    The fragmentation of core-excited BF3 has been studied by means of partial cation and anion yield measurements around the B and F K edges. All detectable ionic fragments are reported, and differences among the fragments are discussed. The observations confirm earlier findings on the dynamics of molecular fragmentation studied by partial ion yields, notably on the influence of Rydberg excitations on fragmentation, the behaviour of anion production near threshold, and the importance of intramolecular rearrangement in the formation of F-2(+) ions.

  • 20. Guitou, M.
    et al.
    Belyaev, A. K.
    Barklem, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Spielfiedel, A.
    Feautrier, N.
    Inelastic Mg plus H collision processes at low energies2011In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 44, no 3, p. 035202-Article in journal (Refereed)
    Abstract [en]

    Full quantum scattering calculations of cross sections for low-energy near-threshold inelastic Mg+H collisions are reported, such processes being of interest for modelling of Mg spectral lines in stellar atmospheres. The calculations are made for three transitions between the ground and two lowest excited Mg states, Mg(3s(2) S-1(0)), Mg(3s3p P-3) and Mg(3s3p P-1). The calculations are based on adiabatic potentials and nonadiabatic couplings for the three low-lying (2)Sigma(+) and the first two (2)Pi states, calculated using large active spaces and basis sets. Non-adiabatic regions associated with radial couplings at avoided ionic crossings in the (2)Sigma(+) molecular potentials are found to be the main mechanism for excitation. Cross sections of similar order of magnitude to those obtained in Li+H and Na+H collisions are found. This, together with the fact that the same mechanism is important, suggests that as has been found earlier for Li and Na, processes such as ion pair production may be important in astrophysical modelling of Mg, and motivates continued study of this system including all states up to and including the ionic limit.

  • 21.
    Hedin, L
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Soft X-Ray Physics.
    Eland, D
    Karlsson, L
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Soft X-Ray Physics.
    Feifel, R
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Soft X-Ray Physics.
    An x-ray absorption and a normal Auger study of the fine structure in the S2p(-1) region of the CS2 molecule2009In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 42, no 8, p. 085102-Article in journal (Refereed)
    Abstract [en]

    The photoabsorption spectrum of the CS2 molecule has been recorded in the vicinity of the two S2p(3/2,1/2) ionization limits at 169.806 eV and 171.075 eV. Synchrotron radiation was used with photon energies covering the energy range between 160 eV and 175 eV. Extensive structure is observed below the ionization limits. It is associated with transitions to both valence and Rydberg states. The latter contain vibrational fine structure due to excitations of the nu(3) asymmetric stretching mode. The vibrational energy is approximately 195 meV in close agreement with previous results obtained from photoelectron spectra for the S2p(3/2,1/2) single-hole states. Above the ionization limits, a resonance is observed in the ionization continuum. An electron spectrum recorded on top of this resonance reveals S2p(-1) VV Auger transitions at high resolution.

  • 22. Holland, D. M. P.
    et al.
    Potts, A. W.
    Karlsson, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Novak, I.
    Zaytseva, I. L.
    Trofimov, A. B.
    Gromov, E. V.
    Schirmer, J.
    An experimental and theoretical study of the valence shell photoelectron spectrum of bromochlorofluoromethane2010In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 43, no 13, p. 135101-Article in journal (Refereed)
    Abstract [en]

    The complete valence shell photoelectron spectrum of bromochlorofluoromethane (CHFClBr), covering the binding energy range similar to 10-50 eV, has been recorded using synchrotron radiation and the observed structure has been interpreted using ionization energies and relative spectral intensities computed using the third-order algebraic-diagrammatic-construction (ADC(3)) scheme for the one-particle Green's function and the outer valence Green's function (OVGF) method. The theoretical results demonstrate that the inner valence region of the photoelectron spectrum is dominated by satellite structure. Angle-resolved photoelectron spectra, recorded at selected excitation energies, have enabled the orbital assignments for the outer valence bands to be confirmed. The four outermost photoelectron bands, ascribed to the two pairs of orbitals associated with the nominally chlorine and bromine lone-pairs, exhibit characteristic angular distributions. The photon energy dependent variations in the relative photoelectron band intensities provide additional support for the orbital assignments.

  • 23. Jonsell, Svante
    et al.
    Saenz, Alejandro
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Zygelman, Bernard
    Dalgarno, Alexei
    Hydrogen: Antihydrogen Scattering in the Born-Oppenheimer Approximation2004In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 37, no 6, p. 1195-Article in journal (Refereed)
    Abstract [en]

    We calculate the low-energy scattering between hydrogen and antihydrogen atoms in their ground states using the Born–Oppenheimer approximation. Improved results for rearrangement, direct annihilation and elastic scattering are presented. The elastic cross section agrees well with other calculations. For the rearrangement process we confirm a recent result (Armour E A G and Chamberlain C W 2002 J. Phys. B: At. Mol. Opt. Phys. 35 L489) that rearrangement to the N = 23 state of protonium has a larger cross section than rearrangement to the N = 24 state. For both rearrangement cross sections our results are smaller than those obtained by Armour and Chamberlain. The direct annihilation, and its influence on elastic scattering, is calculated using the scattering length for the strong force between the proton and antiproton. This approach gives strong-force effects qualitatively similar, but smaller than those obtained in another recent work (Voronin A Yu and Carbonell J 2001 Nucl. Phys. A 689 529c).

  • 24.
    Karlsson, Hans O.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Accelerating the convergence of the Lanczos algorithm by the use of a complex symmetric Cholesky factorization: application to correlation functions in quantum molecular dynamics2011In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 44, no 20, p. 205102-Article in journal (Refereed)
    Abstract [en]

    The theoretical description of reactive scattering, photo dissociation and a number of other problems in chemical physics can be formulated in terms of a correlation function between an initial and final state. It is shown by example that the convergence of correlation functions computed using a complex symmetric Lanczos algorithm can be significantly accelerated by using a complex symmetric version of the Cholesky decomposition. In fact, using the standard Lanczos approach without the Cholesky transformation, the correlation function might not converge at all. It is further demonstrated that a stopping criterion for the Lanczos recursions, based on an estimate for the upper bound of the error of the correlation function, can be extended to complex symmetric matrices and used as a reliable stopping criterion for the Cholesky-Lanczos approach.

  • 25.
    Karlsson, Hans O.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Stability of the complex symmetric Lanczos algorithm for computing photodissociation cross sections using smooth exterior scaling or absorbing potentials.2009In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 42, no 12, p. 125205-Article in journal (Refereed)
    Abstract [en]

    The stability of the Lanczos algorithm for computing photodissociation cross sections is studied. The system is discretized on a grid and the discrete variable representation (DVR) is used to represent system operators. The Hamiltonian is augmented with an absorbing potential (AP) or smooth exterior scaling (SES), to enforce outgoing boundary conditions, making it complex symmetric. The main difference between the AP and the SES is that the former adds to the potential energy whereas the latter modifies the kinetic energy operator. Grozdanov et al (2004 J. Phys. B: At. Mol. Opt. Phys. 31 173) observed the fact that the Lanczos recursions could slow down and even stagnate for certain choices of parameters in the AP or SES. Here we show that for the SES, it is important that the maximum kinetic energy of the DVR is adapted to the physical problem or else the Lanczos recursions might be unstable. A similar result was found for the AP; that is, the Lanczos algorithm in order to converge the strength of the absorbing potential should be of the order of the scattering energy of interest. It is shown that with a discretization adopted to the physical problem at hand and a proper choice of parameters, the Lanczos recursions converge and provide accurate results for both the absorbing potential and the smooth exterior scaling.

  • 26.
    Karlsson, Hans O
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry.
    Goscinski, Osvaldo
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry.
    A direct recursive residue generation method: application to photoionization of hydrogen in static electric fields1994In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 27, no 6, p. 1061-1072Article in journal (Refereed)
    Abstract [en]

    In studies of hydrogenic systems via the recursive residue generation method (RRGM) the major bottleneck is the matrix vector product HC, between the Hamiltonian matrix H and a Lanczos vector C. For highly excited states and/or strong perturbations the size of H grows fast leading to storage problems. By making-use of direct methods, i.e. avoidance of explicit construction on of large Hamiltonian matrices, such problems can be overcome. Utilizing the underlying analytical properties of the Laguerre basis e(-lambdar)L(k)2I+2(2lambdar) a direct RRGM (D-RRGM) for the unperturbed hydrogenic Hamiltonian is derived, changing the storage needs from scaling as N2 to 4N where N is the number of radial functions for each factorized H-0(l, m) block with the possibility of parallel processing. A further computational simplification is introduced by putting the expression for the photoionization (PI) cross section in the rational form conventionally used in the representation of density or states (DOS). This allows the construction of the PI cross section directly from the tridiagonal Lanczos matrix avoiding the explicit calculation of individual eigenvalues and eigenvectors. To illustrate and verify the method the PI cross section for a hydrogen atom in a static electric field, for both pi and cr polarization, was calculated for an electric field strength of F = 5714 V cm-1. Sufficiently large basis sets could be employed so that good comparison with experiment and other theoretical work was obtained, including the field-induced modulations near the zero-field ionization limit.

  • 27.
    Karlsson, Hans O
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry.
    Goscinski, Osvaldo
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry.
    Perturbed hydrogenic manifolds studied by the recursive residue generation method1992In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 25, no 23, p. 5015-5028Article in journal (Refereed)
    Abstract [en]

    A method for calculating the perturbation of hydrogenic manifolds, the emerging bound states and resonances, for arbitrary combinations of external fields, is presented. It requires the combined use of complex dilation, an orthonormal Laguerre basis e(-lambdar) L(k)2l+2 (lambdar) rather than the non-orthogonal Sturmians e(-lambdar) L(k)2l+1 (lambdar), and the recursive residue generation method (RRGM) version of the Lanczos algorithm. Generalized eigenvalue problems are avoided. Furthermore, direct computation of the residues of resolvents, transition amplitudes and sum rules is achieved, Comparison with other methods and with previous calculations, suitable for one perturbation at a time, indicates that high accuracy is achieved separately both for the 1s Stark resonance and for the 1s Zeeman effect. Accurate results for the 1s Stark-Zeeman resonance, for various combinations of fields, are given.

  • 28. KARLSSON, HO
    et al.
    GOSCINSKI, O
    A DIRECT RECURSIVE RESIDUE GENERATION METHOD - APPLICATION TO PHOTOIONIZATION OF HYDROGEN IN STATIC ELECTRIC-FIELDS1994In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 27, no 6, p. 1061-1072Article in journal (Refereed)
    Abstract [en]

    In studies of hydrogenic systems via the recursive residue generation method (RRGM) the major bottleneck is the matrix vector product HC, between the Hamiltonian matrix H and a Lanczos vector C. For highly excited states and/or strong perturbations the size of H grows fast leading to storage problems. By making-use of direct methods, i.e. avoidance of explicit construction on of large Hamiltonian matrices, such problems can be overcome. Utilizing the underlying analytical properties of the Laguerre basis e(-lambdar)L(k)2I+2(2lambdar) a direct RRGM (D-RRGM) for the unperturbed hydrogenic Hamiltonian is derived, changing the storage needs from scaling as N2 to 4N where N is the number of radial functions for each factorized H-0(l, m) block with the possibility of parallel processing. A further computational simplification is introduced by putting the expression for the photoionization (PI) cross section in the rational form conventionally used in the representation of density or states (DOS). This allows the construction of the PI cross section directly from the tridiagonal Lanczos matrix avoiding the explicit calculation of individual eigenvalues and eigenvectors. To illustrate and verify the method the PI cross section for a hydrogen atom in a static electric field, for both pi and cr polarization, was calculated for an electric field strength of F = 5714 V cm-1. Sufficiently large basis sets could be employed so that good comparison with experiment and other theoretical work was obtained, including the field-induced modulations near the zero-field ionization limit.

  • 29. KARLSSON, HO
    et al.
    GOSCINSKI, O
    PERTURBED HYDROGENIC MANIFOLDS STUDIED BY THE RECURSIVE RESIDUE GENERATION METHOD1992In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 25, no 23, p. 5015-5028Article in journal (Refereed)
    Abstract [en]

    A method for calculating the perturbation of hydrogenic manifolds, the emerging bound states and resonances, for arbitrary combinations of external fields, is presented. It requires the combined use of complex dilation, an orthonormal Laguerre basis e(-lambdar) L(k)2l+2 (lambdar) rather than the non-orthogonal Sturmians e(-lambdar) L(k)2l+1 (lambdar), and the recursive residue generation method (RRGM) version of the Lanczos algorithm. Generalized eigenvalue problems are avoided. Furthermore, direct computation of the residues of resolvents, transition amplitudes and sum rules is achieved, Comparison with other methods and with previous calculations, suitable for one perturbation at a time, indicates that high accuracy is achieved separately both for the 1s Stark resonance and for the 1s Zeeman effect. Accurate results for the 1s Stark-Zeeman resonance, for various combinations of fields, are given.

  • 30. Khodorkovskii, M. A.
    et al.
    Murashov, S. V.
    Artamonova, T. O.
    Beliaeva, A. A.
    Rakcheeva, L. P.
    Pastor, A. A.
    Serdobintsev, P. Yu
    Timofeev, N. A.
    Shevkunov, I. A.
    Dement'ev, I. A.
    Nordgren, Joseph
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Electronic spectra of ArXe molecules in the region of Xe* (5d, 7s, 7p, 6p '), 80 300-89 500 cm(-1), using resonantly enhanced multiphoton ionization2010In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 43, no 23, p. 235101-Article in journal (Refereed)
    Abstract [en]

    The electronic spectra of ArXe molecules in the 80 300-89 500 cm(-1) region were recorded by (2 + n) and (3 + n) REMPI methods. The vibrational progressions attributed to transitions of molecules from the ground state to the bounded excited state and wide unstructured bands related to transitions to the continuous upper state were obtained. The molecular constants of ArXe* were calculated for all the observed progressions in the 80 300-87 000 cm(-1) region as an approximation of an anharmonic oscillator and the Morse potential. For different excited states the energy of harmonic oscillator and the dissociation energy are changed from 10 to 100 cm(-1) and from 70 to 750 cm(-1), respectively.

  • 31. Khodorkovskii, M. A.
    et al.
    Murashov, S. V.
    Artamonova, T. O.
    Beliaeva, A. A.
    Rakcheeva, L. P.
    Pastor, A. A.
    Serdobintsev, P. Yu
    Timofeev, N. A.
    Shevkunov, I. A.
    Dement'ev, I. A.
    Nordgren, Joseph
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Electronic spectra of ArXe molecules in the region of Xe* (6s ', 6p, 5d), 77 000-80 200 cm(-1), using resonantly enhanced multiphoton ionization2010In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 43, no 15, p. 155101-Article in journal (Refereed)
    Abstract [en]

    The excited electronic states of ArXe molecules in the region 77 000-80 200 cm(-1) were studied using the (2+1) and (3+1) resonance-enhanced multiphoton ionization methods. The use of different methods of multi-photon excitation and Ar+ ion registration allowed us to obtain some new data. Molecular constants were obtained for previously unknown excited states of molecules with the following dissociation limits: ArXe* -> (ArS0)-S-1+Xe*6p[5/2](3) with Omega = 2, 3 symmetry; (ArS0)-S-1+Xe*6p[3/2](2) with Omega = 1, 2 symmetry; (XeS1)-S-0 -> Xe*6s'[1/2](1)(0) with Omega = 0(+) symmetry.

  • 32. Larsson, M.
    et al.
    Salen, P.
    van der Meulen, P.
    Schmidt, H. T.
    Thomas, R. D.
    Feifel, Raimund
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Piancastelli, Maria Novella
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Fang, L.
    Murphy, B. F.
    Osipov, T.
    Berrah, N.
    Kukk, E.
    Ueda, K.
    Bozek, J. D.
    Bostedt, C.
    Wada, S.
    Richter, R.
    Feyer, V.
    Prince, K. C.
    Double core-hole formation in small molecules at the LCLS free electron laser2013In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 46, no 16 SI, article id 164030Article in journal (Refereed)
    Abstract [en]

    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 CO2, N2O 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.

  • 33.
    Lawson, K. D.
    et al.
    UKAEA/CCFE, Culham Science Centre, Abingdon, OX14 3DB, United Kingdom.
    Andersson Sundén, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Binda, Federico
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Cecconello, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Dzysiuk, Nataliia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ericsson, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Eriksson, Jacob
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hellesen, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hjalmarsson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Skiba, Mateusz
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Zychor, I
    Natl Ctr Nucl Res NCBJ, PL-05400 Otwock, Poland.
    Population modelling of the He II energy levels in tokamak plasmas: I. Collisional excitation model2019In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 52, no 4, article id 045001Article in journal (Refereed)
    Abstract [en]

    Helium is widely used as a fuel or minority gas in laboratory fusion experiments, and will be present as ash in DT thermonuclear plasmas. It is therefore essential to have a good understanding of its atomic physics. To this end He II population modelling has been undertaken for the spectroscopic levels arising from shells with principal quantum number n = 1-5. This paper focuses on a collisional excitation model; ionisation and recombination will be considered in a subsequent article. Heavy particle collisional excitation rate coefficients have been generated to supplement the currently-available atomic data for He II, and are presented for proton, deuteron, triton and alpha-particle projectiles. The widely-used criterion for levels within an n shell being populated in proportion to their statistical weights is reassessed with the most recent atomic data, and found not to apply to the He II levels at tokamak densities (10(18)-10(21) m(-3)). Consequences of this and other likely sources of errors are quantified, as is the effect of differing electron and ion temperatures. Line intensity ratios, including the so-called 'branching ratios' and the fine-structure beta(1), beta(2), beta(3), and gamma ratios, are discussed, the latter with regard to their possible use as diagnostics.

  • 34.
    Lundwall, Marcus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Fink, Reinhold
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Tchaplyguine, M.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Öhrwall, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Bergersen, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Peredkov, S.
    Rander, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Shell-dependent core-level chemical shifts observed in free xenon clusters2006In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 39, no 24, p. 5225-5235Article in journal (Refereed)
    Abstract [en]

    Photoelectron and Auger electron spectra following Xe-3d and Xe-4d ionization of free xenon clusters have been measured using synchrotron radiation. The atom-to-surface and atom-to-bulk binding energy shifts found in the Xe-3d and the subsequent M5N4,5N4,5 Auger decay are about 15% larger than those observed in the Xe-4d and N 4,5O2,3O2,3 measurements. This experimental result is also considered theoretically.

  • 35.
    Lundwall, Marcus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Bergersen, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Rander, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Öhrwall, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Tchaplyguine, M.
    Peredkov, S.
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Photon energy dependent intensity variations observed in Auger spectra of free argon clusters2006In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 39, no 16, p. 3321-3333Article in journal (Refereed)
    Abstract [en]

    Photon energy dependent intensity variations are experimentally observed in the L2,3M2,3M2,3 Auger spectra of argon clusters. Two cluster sizes are examined in the present study. Extrinsic scattering effects, both elastic and inelastic, involving the photoelectron are discussed and suggested as the explanation of the variations in the Auger signal. The atoms in the first few coordination shells surrounding the core-ionized atom are proposed to be the main targets for the scattering processes.

  • 36. Motomura, K.
    et al.
    Fukuzawa, H.
    Son, S-K
    Mondal, S.
    Tachibana, T.
    Ito, Y.
    Kimura, M.
    Nagaya, K.
    Sakai, T.
    Matsunami, K.
    Wada, S.
    Hayashita, H.
    Kajikawa, J.
    Liu, X-J
    Feifel, Raimund
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Johnsson, P.
    Siano, M.
    Kukk, E.
    Rudek, B.
    Erk, B.
    Foucar, L.
    Robert, E.
    Miron, C.
    Tono, K.
    Inubushi, Y.
    Hatsui, T.
    Yabashi, M.
    Yao, M.
    Santra, R.
    Ueda, K.
    Sequential multiphoton multiple ionization of atomic argon and xenon irradiated by X-ray free-electron laser pulses from SACLA2013In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 46, no 16 SI, article id 164024Article in journal (Refereed)
    Abstract [en]

    We have investigated multiphoton multiple ionization of argon and xenon atoms at 5 keV using a new x-ray free electron laser (XFEL) facility, the SPring-8 Angstrom Compact free electron LAser (SACLA) in Japan. The experimental results are compared with the new theoretical results presented here. The absolute fluence of the XFEL pulse has been determined with the help of the calculations utilizing two-photon processes in the argon atom. The high charge states up to +22 observed for Xe in comparison with the calculations point to the occurrence of sequential L-shell multiphoton absorption and of resonance-enabled x-ray multiple ionization.

  • 37. Nagaya, K.
    et al.
    Sugishima, A.
    Iwayama, H.
    Murakami, H.
    Yao, M.
    Fukuzawa, H.
    Liu, X-J
    Motomura, K.
    Ueda, K.
    Saito, N.
    Foucar, L.
    Rudenko, A.
    Kurka, M.
    Kuehnel, K-U
    Ullrich, J.
    Czasch, A.
    Doerner, R.
    Feifel, Raimund
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Nagasono, M.
    Higashiya, A.
    Yabashi, M.
    Ishikawa, T.
    Togashi, T.
    Kimura, H.
    Ohashi, H.
    Unusual under-threshold ionization of neon clusters studied by ion spectroscopy2013In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 46, no 16 SI, article id 164023Article in journal (Refereed)
    Abstract [en]

    We carried out time-of-flight mass spectrometry for neon clusters that were exposed to intense free electron laser pulses with the wavelength of 62 nm, which induce optical transition from the ground state (2s(2) 2p(6)) to an excited state (2s(2) 2p(5) nl) in the Ne atoms. In contrast to Ne+ ions produced by two-photon absorption from isolated Ne atoms, the Ne+ ion yield from Ne clusters shows a linear dependence on the laser intensity (I). We discuss the ionization mechanisms which give the linear behaviour with respect to I and expected features in the electron emission spectrum.

  • 38. Pedersoli, E.
    et al.
    Loh, N. D.
    Capotondi, F.
    Hampton, C. Y.
    Sierra, R. G.
    Starodub, D.
    Bostedt, C.
    Bozek, J.
    Nelson, A. J.
    Aslam, M.
    Li, S.
    Dravid, V. P.
    Martin, A. V.
    Aquila, A.
    Barty, A.
    Fleckenstein, H.
    Gumprecht, L.
    Liang, M.
    Nass, K.
    Schulz, J.
    White, T. A.
    Coppola, N.
    Bajt, S.
    Barthelmess, M.
    Graafsma, H.
    Hirsemann, H.
    Wunderer, C.
    Epp, S. W.
    Erk, B.
    Rudek, B.
    Rudenko, A.
    Foucar, L.
    Kassemeyer, S.
    Lomb, L.
    Rolles, D.
    Shoeman, R. L.
    Steinbrener, J.
    Hartmann, R.
    Hartmann, A.
    Hauser, G.
    Holl, P.
    Kimmel, N.
    Reich, C.
    Soltau, H.
    Weidenspointner, G.
    Benner, W. H.
    Farquar, G. R.
    Hau-Riege, S. P.
    Hunter, M. S.
    Ekeberg, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Hantke, Max
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Maia, Filipe R. N. C.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Tobias, H. J.
    Marchesini, S.
    Frank, M.
    Strueder, L.
    Schlichting, I.
    Ullrich, J.
    Chapman, H. N.
    Bucksbaum, P. H.
    Kiskinova, M.
    Bogan, M. J.
    Mesoscale morphology of airborne core-shell nanoparticle clusters: x-ray laser coherent diffraction imaging2013In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 46, no 16 SI, p. 164033-Article in journal (Refereed)
    Abstract [en]

    Unraveling the complex morphology of functional materials like core-shell nanoparticles and its evolution in different environments is still a challenge. Only recently has the single-particle coherent diffraction imaging (CDI), enabled by the ultrabright femtosecond free-electron laser pulses, provided breakthroughs in understanding mesoscopic morphology of nanoparticulate matter. Here, we report the first CDI results for Co@SiO2 core-shell nanoparticles randomly clustered in large airborne aggregates, obtained using the x-ray free-electron laser at the Linac Coherent Light Source. Our experimental results compare favourably with simulated diffraction patterns for clustered Co@SiO2 nanoparticles with similar to 10 nm core diameter and similar to 30 nm shell outer diameter, which confirms the ability to resolve the mesoscale morphology of complex metastable structures. The findings in this first morphological study of core-shell nanomaterials are a solid base for future time-resolved studies of dynamic phenomena in complex nanoparticulate matter using x-ray lasers.

  • 39.
    Piancastelli, Maria Novella
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Céolin, Denis
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Travnikova, Oksana
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Bao, Zhuo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Hoshino, M.
    Tanaka, T.
    Kato, H.
    Tanaka, H.
    Harries, J.R.
    Tamenori, Y.
    Pümper, G.
    Lischke, T.
    Liu, X.-J
    Ueda, K.
    A High-resolution Study of Resonant Auger Decay Processes in N2O After Core Electron Excitation from Terminal Nitrogen, Central Nitrogen and Oxygen Atoms to the 3π LUMO2007In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 40, no 17, p. 3357-3365Article in journal (Refereed)
    Abstract [en]

    Decay spectra of N2O following excitation to the N terminal (Nt) → π*, N central (Nc) → π* and O is → π* intermediate states are reported. The final states reached after participator decay show resonant enhancement consistent with a local-density-of-states analysis based on the Mulliken population of the valence molecular orbitals. In particular, the X-state is resonantly enhanced mostly after excitation from the Nt 1s and the O Is core levels to the π*, while the B-state is mostly enhanced following the excitation of the Nc Is → π* intermediate state. Below the Nt Is threshold, the lowest lying peak related to spectator decay falls at lower binding energy than the highest lying participator peak. This can be attributed to a particularly strong screening effect exerted by the excited electron in the LUMO.

  • 40.
    Piancastelli, Maria Novella
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Goldsztejn, Gildas
    Marchenko, Tatiana
    Guillemin, Renaud
    Kushawaha, Rajesh K.
    Journel, Loic
    Carniato, Stephane
    Rueff, Jean-Pascal
    Ceolin, Denis
    Simon, Marc
    Core-hole-clock spectroscopies in the tender x-ray domain2014In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 47, no 12, p. 124031-Article in journal (Refereed)
    Abstract [en]

    The core-hole-clock method to observe dynamical phenomena in molecular photoexcitation on the 1 fs-hundreds-of-attoseconds time scale is illustrated with examples from resonant inelastic x-ray scattering (RIXS) and resonant-Auger-emission experiments on the prototypical CH3Cl system in the tender x-ray domain. In particular, a direct comparison between RIXS and resonant-Auger data allows us to unravel subtle details of nuclear motion and interplay of potential curves of the intermediate and final states reached upon deep-core excitation.

  • 41.
    Piancastelli, Maria Novella
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. UPMC Univ Paris 06, Sorbonne Univ, CNRS, Lab Chim Phys Mat & Rayonnement,UMR 7614, F-75005 Paris, France.
    Guillemin, R.
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, Lab Chim Phys Mat & Rayonnement,UMR 7614, F-75005 Paris, France..
    Marchenko, T.
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, Lab Chim Phys Mat & Rayonnement,UMR 7614, F-75005 Paris, France..
    Journel, L.
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, Lab Chim Phys Mat & Rayonnement,UMR 7614, F-75005 Paris, France..
    Travnikova, O.
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, Lab Chim Phys Mat & Rayonnement,UMR 7614, F-75005 Paris, France..
    Marin, T.
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, Lab Chim Phys Mat & Rayonnement,UMR 7614, F-75005 Paris, France..
    Goldsztejn, G.
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, Lab Chim Phys Mat & Rayonnement,UMR 7614, F-75005 Paris, France..
    de Miranda, B. Cunha
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, Lab Chim Phys Mat & Rayonnement,UMR 7614, F-75005 Paris, France..
    Ismail, I.
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, Lab Chim Phys Mat & Rayonnement,UMR 7614, F-75005 Paris, France..
    Simon, M.
    UPMC Univ Paris 06, Sorbonne Univ, CNRS, Lab Chim Phys Mat & Rayonnement,UMR 7614, F-75005 Paris, France..
    New achievements on relaxation dynamics of atoms and molecules photoexcited in the tender x-ray domain at synchrotron SOLEIL2017In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 50, no 4, article id 042001Article, review/survey (Refereed)
    Abstract [en]

    The so-called 'tender' x-ray domain, from 2 to 13 keV, has recently become available for atomic and molecular studies at the French synchrotron SOLEIL with state-of-the-art photon and electron energy resolution. We investigated a wealth of new phenomena by means of photoelectron and Auger spectroscopy and electron-ion coincidence techniques. The list includes recoil due to the photoelectron's momentum, ultrafast nuclear motion on the femto-and sub-femtosecond time scale, double-core-hole studies, electron recapture effects, exotic Auger decay pathways, deep-edge molecular-frame photoelectron angular distribution studies, and core-hole localization/delocalization phenomena for deep-core vacancies. We demonstrate that the newly accessible extended photon energy range does not simply allow studying more systems with deeper core edges, but opens a totally new horizon in what concerns electron and nuclear dynamics of deep-core-excited and core-ionized isolated species.

  • 42. Powis, I.
    et al.
    Zaytseva, I. L.
    Trofimov, A. B.
    Schirmer, J.
    Holland, D. M. P.
    Potts, A. W.
    Karlsson, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    A study of the valence shell electronic structure and photoionization dynamics of selenophene2007In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 40, no 11, p. 2019-2041Article in journal (Refereed)
    Abstract [en]

    The photoelectron spectrum of selenophene has been recorded using synchrotron radiation in the photon energy range 20-80 eV and the inner valence region has been studied in detail for the first time. Green's function methods have been employed to evaluate the energies and spectral intensities of all valence shell ionization transitions and the results have facilitated an interpretation of the experimental spectra. Strong configuration interaction results in a redistribution of the intensity associated with the low lying pi(1)( 1b(1)) orbital amongst several satellite states located in the outer valence region. The continuum multiple scattering approach has been used to calculate photoelectron asymmetry parameters for selenophene, thiophene and hydrogen sulphide, and these theoretical predictions have been compared with the corresponding experimental data to assess the influence of Cooper minima and shape resonances. The comparison indicates that the Se 4p and the S 3p Cooper minima have little effect on the valence shell photoionization dynamics of selenophene and thiophene, respectively. This outcome is discussed in connection with the closely related hydrogen selenide and hydrogen sulphide molecules where strong resonant phenomena are observed.

  • 43.
    Rosso, A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Öhrwall, G.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Tchaplyguine, M.
    Svensson, S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Rander, T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Lundwall, M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Lindblad, A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Björneholm, O.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Adsorption of chloromethane molecules on free argon clusters2008In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 41, no 8, p. 085102(1)-085102(6)Article in journal (Refereed)
    Abstract [en]

    Binary chloromethane-argon clusters were investigated by means of synchrotron-radiation-based valence and core level photoelectron spectroscopies. The host argon clusters were produced by adiabatic expansion and exposed to chloromethane molecules using the pick-up technique. The study of the valence spectrum showed that heterogeneous clusters were formed. The spatial distribution of chloromethane in the clusters was determined through the analysis of core level photoelectron spectra recorded at the Ar 2p and Cl 2p thresholds and by comparisons with pure argon cluster and pure chloromethane cluster spectra. By analysing the peak positions, widths and integrated intensities of the cluster components we concluded that the chloromethane molecules are mainly located near surface sites.

  • 44. Saenz, Alejandro
    et al.
    Weyrich, Wolf
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    The first Born approximation and absolute scattering cross sections1996In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 29, no 1, p. 97-113Article in journal (Refereed)
    Abstract [en]

    The problem of bringing experimental electron-scattering cross sections to the absolute scale using the so-called Lassettre theorem is addressed. Experimental data that have been measured by electron-scattering experiments for different incident energies (in the range of 100 to 600 eV) and have been normalized on the basis of this theorem are compared with absolute cross sections that have been calculated within the first Born approximation by means of the complex-scaling method. The agreement is not found to be satisfactory even for the smallest values of momentum transfer. This, however, is a contradiction to Lassettre's theorem. A new normalization procedure for the experimental data is suggested that has yielded good agreement between the present calculated and the measured data even for a comparatively large range of momentum transfer. This indicates an extended range of validity of the first Born approximation.

  • 45.
    Sanchez-Gonzalez, A.
    et al.
    Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London SW7 2AZ, England..
    Barillot, T. R.
    Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London SW7 2AZ, England..
    Squibb, R. J.
    Univ Gothenburg, Dept Phys, SE-41296 Gothenburg, Sweden..
    Kolorenc, P.
    Charles Univ Prague, Fac Math & Phys, Inst Theoret Phys, CR-18000 Prague, Czech Republic..
    Agåker, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Averbukh, V.
    Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London SW7 2AZ, England..
    Bearpark, M. J.
    Univ London Imperial Coll Sci Technol & Med, Dept Chem, London SW7 2AZ, England..
    Bostedt, C.
    SLAC Natl Accelerator Lab, LCLS, Menlo Pk, CA 94025 USA..
    Bozek, J. D.
    SOLEIL Synchrotron, PLEIADES Beamline, LOrme Merisiers, F-91192 Gif Sur Yvette, France..
    Bruce, S.
    Univ Texas, Texas Ctr High Energy Dens Sci CHEDS, Austin, TX 78712 USA..
    Montero, S. Carron
    SLAC Natl Accelerator Lab, LCLS, Menlo Pk, CA 94025 USA..
    Coffee, R. N.
    SLAC Natl Accelerator Lab, LCLS, Menlo Pk, CA 94025 USA..
    Cooper, B.
    Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London SW7 2AZ, England..
    Cryan, J. P.
    SLAC Natl Accelerator Lab, PULSE Inst, Menlo Pk, CA 94025 USA..
    Dong, Minjie
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Eland, J. H. D.
    Univ Oxford, Dept Chem, Oxford OX1 3QZ, England..
    Fang, L.
    Univ Texas, Texas Ctr High Energy Dens Sci CHEDS, Austin, TX 78712 USA..
    Fukuzawa, H.
    Tohoku Univ, Inst Multidisciplinary Res Adv Mat, Sendai, Miyagi 9808577, Japan..
    Guehr, M.
    SLAC Natl Accelerator Lab, PULSE Inst, Menlo Pk, CA 94025 USA..
    Ilchen, M.
    European XFEL GmbH, D-22761 Hamburg, Germany..
    Johnsson, A. S.
    Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London SW7 2AZ, England..
    Liekhus-S, C.
    SLAC Natl Accelerator Lab, PULSE Inst, Menlo Pk, CA 94025 USA.;Stanford Univ, Dept Phys, Stanford, CA 94305 USA.;Stanford Univ, Dept Appl Phys, Stanford, CA 94305 USA..
    Marinelli, A.
    SLAC Natl Accelerator Lab, LCLS, Menlo Pk, CA 94025 USA..
    Maxwell, T.
    SLAC Natl Accelerator Lab, LCLS, Menlo Pk, CA 94025 USA..
    Motomura, K.
    Tohoku Univ, Inst Multidisciplinary Res Adv Mat, Sendai, Miyagi 9808577, Japan..
    Mucke, Melanie
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Natan, A.
    SLAC Natl Accelerator Lab, PULSE Inst, Menlo Pk, CA 94025 USA.;Stanford Univ, Dept Phys, Stanford, CA 94305 USA.;Stanford Univ, Dept Appl Phys, Stanford, CA 94305 USA..
    Osipov, T.
    SLAC Natl Accelerator Lab, LCLS, Menlo Pk, CA 94025 USA..
    Östlin, Christofer
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Pernpointner, M.
    Heidelberg Univ, Theoret Chem, D-69120 Heidelberg, Germany..
    Petrovic, V. S.
    SLAC Natl Accelerator Lab, PULSE Inst, Menlo Pk, CA 94025 USA.;Stanford Univ, Dept Phys, Stanford, CA 94305 USA.;Stanford Univ, Dept Appl Phys, Stanford, CA 94305 USA..
    Robb, M. A.
    Univ London Imperial Coll Sci Technol & Med, Dept Chem, London SW7 2AZ, England..
    Sathe, C.
    Lund Univ, MAX IV Lab, SE-22100 Lund, Sweden..
    Simpson, E. R.
    Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London SW7 2AZ, England..
    Underwood, J. G.
    UCL, Dept Phys & Astron, London WC1E 6BT, England..
    Vacher, Morgane
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Theoretical Chemistry. Univ London Imperial Coll Sci Technol & Med, Dept Chem, London SW7 2AZ, England..
    Walke, D. J.
    Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London SW7 2AZ, England..
    Wolf, T. J. A.
    SLAC Natl Accelerator Lab, PULSE Inst, Menlo Pk, CA 94025 USA..
    Zhaunerchyk, V.
    Univ Gothenburg, Dept Phys, SE-41296 Gothenburg, Sweden..
    Rubensson, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Berrah, N.
    Western Michigan Univ, Dept Phys, Kalamazoo, MI 49008 USA..
    Bucksbaum, P. H.
    SLAC Natl Accelerator Lab, PULSE Inst, Menlo Pk, CA 94025 USA.;Stanford Univ, Dept Phys, Stanford, CA 94305 USA.;Stanford Univ, Dept Appl Phys, Stanford, CA 94305 USA..
    Ueda, K.
    Tohoku Univ, Inst Multidisciplinary Res Adv Mat, Sendai, Miyagi 9808577, Japan..
    Feifel, R.
    Univ Gothenburg, Dept Phys, SE-41296 Gothenburg, Sweden..
    Frasinski, L. J.
    Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London SW7 2AZ, England..
    Marangos, J. P.
    Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London SW7 2AZ, England..
    Auger Electron and Photoabsorption Spectra of Glycine in the Vicinity of the Oxygen K-edge Measured with an X-FEL2015In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 48, no 23, article id 234004Article in journal (Refereed)
    Abstract [en]

    We report the first measurement of the near oxygen K-edge auger spectrum of the glycine molecule. Our work employed an x-ray free electron laser as the photon source operated with input photon energies tunable between 527 and 547 eV. Complete electron spectra were recorded at each photon energy in the tuning range, revealing resonant and non-resonant auger structures. Finally ab initio theoretical predictions are compared with the measured above the edge auger spectrum and an assignment of auger decay channels is performed.

  • 46.
    Seibert, M. Marvin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Boutet, Sebastien
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Svenda, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Ekeberg, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Maia, Filipe R. N. C.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Bogan, Michael J.
    Timneanu, Nicusor
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Barty, Anton
    Hau-Riege, Stefan
    Caleman, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Frank, Matthias
    Benner, Henry
    Lee, Joanna Y.
    Marchesini, Stefano
    Shaevitz, Joshua W.
    Fletcher, Daniel A.
    Bajt, Sasa
    Andersson, Inger
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Chapman, Henry N.
    Hajdu, Janos
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Femtosecond diffractive imaging of biological cells2010In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 43, no 19, p. 194015-Article in journal (Refereed)
    Abstract [en]

    In a flash diffraction experiment, a short and extremely intense x-ray pulse illuminates the sample to obtain a diffraction pattern before the onset of significant radiation damage. The over-sampled diffraction pattern permits phase retrieval by iterative phasing methods. Flash diffractive imaging was first demonstrated on an inorganic test object (Chapman et al 2006 Nat. Phys. 2 839-43). We report here experiments on biological systems where individual cells were imaged, using single, 10-15 fs soft x-ray pulses at 13.5 nm wavelength from the FLASH free-electron laser in Hamburg. Simulations show that the pulse heated the sample to about 160 000 K but not before an interpretable diffraction pattern could be obtained. The reconstructed projection images return the structures of the intact cells. The simulations suggest that the average displacement of ions and atoms in the hottest surface layers remained below 3 angstrom during the pulse.

  • 47. Sorensen, S. L.
    et al.
    Borve, K. J.
    Feifel, R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Soft X-Ray Physics.
    de Fanis, A.
    Ueda, K.
    The O 1s photoelectron spectrum of molecular oxygen revisited2008In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 41, no 9, p. 095101-Article in journal (Refereed)
    Abstract [en]

    High-resolution photoelectron spectra of the inner-shell levels of molecular oxygen have been measured using synchrotron radiation. The vibrational structure of the two magnetically-split core-shell components is analyzed based upon ab initio calculations. The ratio between the intensities of the two components was analyzed at several different ionization energies up to about 600 eV, and the same is discussed and compared to high-energy ionization intensities. A theoretical calculation shows very good agreement with the measured spectra. The calculation implements a model where two parity components make up the 4Σ peak profile. The gerade-ungerade energy split for this state is found to be 50 meV.

  • 48.
    Stegeby, Henrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Theoretical Chemistry.
    Kowalewski, Markus
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computational Science.
    Piszczatowski, Konrad
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Theoretical Chemistry.
    Karlsson, Hans O.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Theoretical Chemistry.
    Wave packet simulations of antiproton scattering on molecular hydrogen2015In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 48, no 19, p. 195204:1-7, article id 195204Article in journal (Refereed)
  • 49.
    Stegeby, Henrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Theoretical Chemistry.
    Piszczatowski, Konrad
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Theoretical Chemistry.
    Resonance states in the hydrogen-antihydrogen system from a nonadiabatic treatment2016In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 49, no 1, article id 014002Article in journal (Refereed)
    Abstract [en]

    The quantum-mechanical four-body problem for the hydrogen-antihydrogen system has been solved by means of the variational implementation of the coupled-arrangement channel method. Wave functions have been formed using the Gaussian expansion method (GEM) in Jacobi coordinates; they explicitly include components corresponding to the rearrangement from hydrogen and antihydrogen (H + (H) over bar into protonium and positronium (Pn + Ps). We analyze the solutions belonging to the discretized spectrum of the four-body eigenvalue problem, searching for resonance states at energies just below the H-(H) over bar dissociation energy threshold by means of the stabilization method and complex scaling.

  • 50. Stolte, W. C.
    et al.
    Guillemin, R.
    Demchenko, I. N.
    Öhrwall, G.
    Yu, S-W
    Young, J. A.
    Taupin, M.
    Hemmers, O.
    Piancastelli, Maria Novella
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Lindle, D. W.
    Inner-shell photofragmentation of Cl-22010In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 43, no 15, p. 155202-Article in journal (Refereed)
    Abstract [en]

    We report an extensive study on partial-ion-yield spectroscopy around the Cl 1s and 2p ionization thresholds for Cl-2. All positive ion channels, several with the same mass/charge ratio, which could be distinguished by taking the advantage of the Cl-37 isotope, have been measured at a photon resolution of nearly 6500. At the Cl 1s ionization threshold, no significant differences are reported between the absorption and the partial-ion yields. In contrast, near the 2p ionization thresholds, we detect large variations in the fragmentation patterns following excitations to the Rydberg series when comparing the atomic fragment ions to the molecular fragment ions. We attribute the different behaviours to the more-or-less diffuse nature of Rydberg states with different angular momenta.

12 1 - 50 of 58
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