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Janeček I, Stachoň M, Gadea FX, Kalus R. Fragmentation of Kr N+ clusters after electron impact ionization II. Long-time dynamics simulations of Kr 7+ evolution and the role of initial electronic excitation. Phys Chem Chem Phys 2018; 19:25423-25440. [PMID: 28895597 DOI: 10.1039/c7cp03940a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Long time simulations, up to 100 ns, have been performed for the fragmentation of Kr7+ clusters after electron impact ionization. They rely on DIM approaches and hybrid non-adiabatic dynamics combining mean field and decoherence driven either by Tully fewest switches (TFS) algorithm or through electronic amplitude (AMP) calculations. With both methods, for the first time, when the initial electronic excited state belongs to group II correlating to P1/2 atomic ions, the fragmentation ratio in mainly monomer and dimer ions agrees very well with known experimental results. A complex non-adiabatic dynamics is found where initial neutral monomer evaporations due to gradual deexcitation over electronic states of group II are followed by a non-adiabatic transition across a wide energy gap of the spin-orbit origin to electronic states of group I. The resulting excess of kinetic energy causes the final fragmentation of charged intermediate fragments to stable ionic monomers or dimers. Characteristic times of these processes have been estimated. The kinetic energy distribution of the neutral and ionic monomers (the dominating final fragments) has been analyzed in detail. Interestingly they exhibit some signature of the initial excited electronic state which could allow for an experimental identification.
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Affiliation(s)
- Ivan Janeček
- Institute of Geonics of the AS CR, v.v.i., and Institute of Clean Technologies for Mining and Utilization of Raw Materials for Energy Use, Studentská 1768, 708 00 Ostrava, Czech Republic.
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Janeček I, Naar P, Stachoň M, Gadea FX, Kalus R. Fragmentation of KrN+ clusters after electron impact ionization. Short-time dynamics simulations and approximate multi-scale treatment. Phys Chem Chem Phys 2017; 19:2778-2790. [DOI: 10.1039/c6cp07479k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Post-ionization fragmentation of small ionic krypton clusters, KrN+ (N = 3–13), has been investigated using a semiclassical non-adiabatic dynamics approach with inclusion of electronic quantum decoherence, and compared with experiment.
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Affiliation(s)
- Ivan Janeček
- Institute of Geonics of the AS CR, v.v.i
- and Institute of Clean Technologies for Mining and Utilization of Raw Materials for Energy Use
- 708 00 Ostrava
- Czech Republic
| | - Pavel Naar
- Department of Physics
- Faculty of Sciences
- University of Ostrava
- 701 03 Ostrava
- Czech Republic
| | - Martin Stachoň
- IT4Innovations National Supercomputing Center
- VSB – Technical University of Ostrava
- 708 33 Ostrava
- Czech Republic
| | | | - René Kalus
- IT4Innovations National Supercomputing Center and Department of Applied Mathematics
- VŠB – Technical University of Ostrava
- 708 33 Ostrava
- Czech Republic
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Bartl P, Leidlmair C, Denifl S, Scheier P, Echt O. On the size and structure of helium snowballs formed around charged atoms and clusters of noble gases. J Phys Chem A 2014; 118:8050-9. [PMID: 24128371 PMCID: PMC4166691 DOI: 10.1021/jp406540p] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 09/04/2013] [Indexed: 11/30/2022]
Abstract
Helium nanodroplets doped with argon, krypton, or xenon are ionized by electrons and analyzed in a mass spectrometer. HenNgx(+) ions containing up to seven noble gas (Ng) atoms and dozens of helium atoms are identified; the high resolution of the mass spectrometer combined with advanced data analysis make it possible to unscramble contributions from isotopologues that have the same nominal mass but different numbers of helium or Ng atoms, such as the magic He20(84)Kr2(+) and the isobaric, nonmagic He41(84)Kr(+). Anomalies in these ion abundances reveal particularly stable ions; several intriguing patterns emerge. Perhaps most astounding are the results for HenAr(+), which show evidence for three distinct, solid-like solvation shells containing 12, 20, and 12 helium atoms. This observation runs counter to the common notion that only the first solvation shell is solid-like but agrees with calculations by Galli et al. for HenNa(+) [J. Phys. Chem. A 2011, 115, 7300] that reveal three shells of icosahedral symmetry. HenArx(+) (2 ≤ x ≤ 7) ions appear to be especially stable if they contain a total of n + x = 19 atoms. A sequence of anomalies in the abundance distribution of HenKrx(+) suggests that rings of six helium atoms are inserted into the solvation shell each time a krypton atom is added to the ionic core, from Kr(+) to Kr3(+). Previously reported strong anomalies at He12Kr2(+) and He12Kr3(+) [Kim , J. H.; et al. J. Chem. Phys. 2006, 124, 214301] are attributed to a contamination. Only minor local anomalies appear in the distributions of HenXex(+) (x ≤ 3). The distributions of HenKr(+) and HenXe(+) show strikingly similar, broad features that are absent from the distribution of HenAr(+); differences are tentatively ascribed to the very different fragmentation dynamics of these ions.
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Affiliation(s)
- Peter Bartl
- Institut für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Christian Leidlmair
- Institut für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Olof Echt
- Institut für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
- Department of Physics, University of New Hampshire, Durham, New Hampshire 03824, United States
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Liang YN, Wang F, Guo J. Theoretical study on low-lying electronic states of Kr2(+), Xe2(+), and Rn2(+). J Chem Phys 2013; 138:094319. [PMID: 23485306 DOI: 10.1063/1.4792435] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this work, the equation-of-motion coupled-cluster approach with spin-orbit coupling (SOC) for ionization potentials (IP) at the singles and doubles level (EOMIP-CCSD) is employed to calculate spectroscopic constants of low-lying states of rare gas dimer ions Kr2(+), Xe2(+), and Rn2(+). Two approaches are proposed to include contributions of triples: (1) energies of these states are calculated by adding the IPs from EOMIP-CCSD and the CCSD(T) energy of the rare gas dimers and (2) CCSD(T) energies without SOC for Rg2(+) are first calculated and energies of these states with SOC are determined subsequently using the SOC matrix between these states. The first approach can provide accurate results for the three most stable states, while overestimates bond lengths for the other states. The second approach has been adopted previously and the SOC matrix element between (2)Σ1∕2 (+) and (2)Π1∕2 states was set to be 1/2 times that of the SOC constant. In our work, the SOC matrix elements are determined from the calculated IPs and reasonable results for these states can be achieved with this approach, which could be useful for experimental works.
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Affiliation(s)
- Yan-Ni Liang
- Key Laboratory of Chemical Laser, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China
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Janeček I, Janča T, Naar P, Kalus R, Gadea FX. Multiscale approach combining nonadiabatic dynamics with long-time radiative and non-radiative decay: Dissociative ionization of heavy rare-gas tetramers revisited. J Chem Phys 2013; 138:044303. [DOI: 10.1063/1.4775804] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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Mastalerz R, Zehnder O, Reiher M, Merkt F. Spin–Orbit Coupling and Potential Energy Functions of Ar2+ and Kr2+ by High-Resolution Photoelectron Spectroscopy and ab Initio Quantum Chemistry. J Chem Theory Comput 2012; 8:3671-85. [DOI: 10.1021/ct300078m] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- R. Mastalerz
- Laboratorium
für Physikalische Chemie, ETH Zurich,
8093 Zurich, Switzerland
| | - O. Zehnder
- Laboratorium
für Physikalische Chemie, ETH Zurich,
8093 Zurich, Switzerland
| | - M. Reiher
- Laboratorium
für Physikalische Chemie, ETH Zurich,
8093 Zurich, Switzerland
| | - F. Merkt
- Laboratorium
für Physikalische Chemie, ETH Zurich,
8093 Zurich, Switzerland
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Jaksch S, Ferreira da Silva F, Denifl S, Echt O, Märk TD, Scheier P. Experimental evidence for the existence of an electronically excited state of the proposed dihydrogen radical cation He-H-H-He+. Chemistry 2009; 15:4190-4. [PMID: 19248067 DOI: 10.1002/chem.200802545] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Survival of the weakest: The existence of a new class of centrosymmetric radical cations in which H(2) bridges two identical main group elements was recently proposed in this journal by Uggerud and co-workers. By growing complexes inside helium nanodroplets at subkelvin temperatures, we obtained experimental evidence for the existence of the most weakly bound member of this class, He-H-H-He(+) (see picture), although in a metastable, electronically excited state.In a recent report, Uggerud and co-workers (A. Krapp et al., Chem. Eur. J. 2008, 14, 4028) proposed the existence of a new class of radical cations in which a dihydrogen bridges two identical main group elements. Upon electron impact ionization of helium nanodroplets doped with one or more H(2) molecules we observe various He(x)H(y) (+) cluster ions, including He(2)H(2) (+), which would belong to the proposed class of radical cations. Mass-analyzed kinetic energy scans reveal that the ion is metastable; it dissociates in the field-free region of the mass spectrometer. One reaction is into HeH(2) (+) + He with a low kinetic energy release of 15+/-4 meV. Surprisingly, another unimolecular reaction is observed, into HeH(+) + HeH (or He + H). The probability of this reaction is an order of magnitude higher, and the average kinetic energy release is four times larger. These findings suggest the presence of a metastable electronically excited state; they are consistent with the proposed linear, centrosymmetric ion structure of He-H-H-He(+).
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Affiliation(s)
- Stefan Jaksch
- Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität, Technikerstrasse 25, 6020 Innsbruck, Austria
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Jaksch S, Mauracher A, Bacher A, Denifl S, da Silva FF, Schöbel H, Echt O, Märk TD, Probst M, Bohme DK, Scheier P. Formation of even-numbered hydrogen cluster cations in ultracold helium droplets. J Chem Phys 2009; 129:224306. [PMID: 19071915 DOI: 10.1063/1.3035833] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Neutral hydrogen clusters are grown in ultracold helium nanodroplets by successive pickup of hydrogen molecules. Even-numbered hydrogen cluster cations are observed upon electron-impact ionization with and without attached helium atoms and in addition to the familiar odd-numbered H(n)(+). The helium matrix affects the fragmentation dynamics that usually lead to the formation of overwhelmingly odd-numbered H(n)(+). The use of high-resolution mass spectrometry allows the unambiguous identification of even-numbered H(n)(+) up to n approximately = 120 by their mass excess that distinguishes them from He(n)(+), mixed He(m)H(n)(+), and background ions. The large range in size of these hydrogen cluster ions is unprecedented, as is the accuracy of their definition. Apart from the previously observed magic number n=6, pronounced drops in the abundance of even-numbered cluster ions are seen at n=30 and 114, which suggest icosahedral shell closures at H(6)(+)(H(2))(12) and H(6)(+)(H(2))(54). Possible isomers of H(6)(+) are identified at the quadratic configuration interaction with inclusion of single and double excitations (QCISD)/aug-cc-pVTZ level of theory.
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Affiliation(s)
- S Jaksch
- Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität, Technikerstr. 25, A-6020 Innsbruck, Austria
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Zehnder O, Mastalerz R, Reiher M, Merkt F, Dressler RA. On the R-dependence of the spin-orbit coupling constant: Potential energy functions of Xe(2) (+) by high-resolution photoelectron spectroscopy and ab initio quantum chemistry. J Chem Phys 2008; 128:234306. [PMID: 18570498 DOI: 10.1063/1.2937133] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The pulsed-field-ionization zero-kinetic-energy photoelectron spectrum of Xe(2) has been measured between 97 350 and 108 200 cm(-1), following resonant two-photon excitation via selected vibrational levels of the C 0(u) (+) Rydberg state of Xe(2). Transitions to three of the six low-lying electronic states of Xe(2) (+) could be observed. Whereas extensive vibrational progressions were observed for the transitions to the I(32g) and I(32u) states, only the lowest vibrational levels of the II(12u) state could be detected. Assignments of the vibrational quantum numbers were derived from the analysis of the isotopic shifts and from the modeling of the potential energy curves. Adiabatic ionization energies, dissociation energies, and vibrational constants are reported for the I(32g) and the I(32u) states. Multireference configurational interaction and complete active space self-consistent field calculations have been performed to investigate the dependence of the spin-orbit coupling constant on the internuclear distance. The energies of vibrational levels, measured presently and in a previous investigation (Rupper et al., J. Chem. Phys. 121, 8279 (2004)), were used to determine the potential energy functions of the six low-lying electronic states of Xe(2) (+) using a global model that includes the long-range interaction and treats, for the first time, the spin-orbit interaction as dependent on the internuclear separation.
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Affiliation(s)
- O Zehnder
- Laboratorium für Physikalische Chemie, ETH Zurich, 8093 Zurich, Switzerland
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