On the role of the II(1/2g) state in spontaneous dissociation of krypton and xenon dimer ions

Fedor, Juraj; Echt, Olof; Głuch, K.; Matt-Leubner, S.; Scheier, P.; Märk, T.D.

doi:10.1016/j.cplett.2007.02.030

Cited by 12 publications

(8 citation statements)

References 32 publications

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“… 39 Their multiscale approach is complex; it involves spin–orbit coupling and different time scales to account for initial, nonadiabatic processes as well as radiative and nonradiative transitions between electronically excited states that occur on a microsecond time scale. Metastable dissociation of excited Ng dimer ions has been shown experimentally to occur on this time scale, 76 − 78 with profound differences between light (Ne, Ar) and heavy Ng’s. It remains to be seen if excited states could possibly cause the peculiar broad features in the distributions of He n Kr + and He n Xe + .…”

Section: Resultsmentioning

confidence: 99%

On the Size and Structure of Helium Snowballs Formed around Charged Atoms and Clusters of Noble Gases

et al. 2013

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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 He2084Kr2+ and the isobaric, nonmagic He4184Kr+. 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+ [21568337J. Phys. Chem. A20111157300] 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+ [KimJ. H.16774401J. Chem. Phys.2006124214301] 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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Section: Resultsmentioning

confidence: 99%

On the Size and Structure of Helium Snowballs Formed around Charged Atoms and Clusters of Noble Gases

et al. 2013

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“…H 4 + ͑that merges into a much stronger satellite peak caused by interference with another decay channel 69,70 ͒ and H 5 + are weaker by another order of magnitude. From the width of the H 3 + peak we deduce 71 an average kinetic energy release ͗KER͘ =57Ϯ 2 meV assuming onestep dissociation into H 3 + +H 3 ͑we cannot identify neutral products͒. It is more likely that the reaction proceeds in two distinct steps, emission of a H atom followed by loss of H 2 .…”

Section: A Experimental Resultsmentioning

confidence: 95%

Formation of even-numbered hydrogen cluster cations in ultracold helium droplets

Jaksch

Mauracher

Bacher

et al. 2008

The Journal of Chemical Physics

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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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“…However, it was demonstrated experimentally and theoretically that molecular systems may survive for a long time (microseconds or longer) after the initial excitation trapped in an excited electronic state. In that case, after the faster dark dynamics phase, slow radiative decay is expected to play an important role, as shown experimentally for the dissociation of metastable rare-gas dimers [7][8][9], trimers [16,17], and larger clusters [18][19][20]. This interplay between non-radiative and radiative processes (representing two important decay mechanisms 1 ) is considered here for the first time in a realistic simulation.…”

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confidence: 78%

“…However, because the fast electronic dynamics must be treated carefully, typical time steps are about tenths of femtosecond and integrated trajectories can usually be expanded only up to tens or hundreds of picoseconds, but not much more, due to computational demands. However, experimental time scales are much longer, typically microseconds or more [7][8][9], and this poses a big challenge on the theory. Consequently, methods for a multiscale treatment of molecular dynamics, spanning time scales from picoseconds up to microseconds, have been proposed recently in various fields [10][11][12][13][14][15], usually leaning on an assumption that the fast, picosecond dynamics brings the system to the electronic ground state and internal conversion is achieved.…”

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confidence: 99%

Multiscale non-adiabatic dynamics with radiative decay, case study on the post-ionization fragmentation of rare-gas tetramers

Janeček¹,

Janča²,

Naar³

et al. 2012

EPL

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In this supplementary material, we recollect, for reader's convenience, the general scheme of suggested multiscale model (Sec. 1), and basic informations about approaches used for pilot study: a detailed description of the interaction model (Sec. 2) and dynamical methods used for the dark dynamics step (Sec. 3) reported previously in two preceding studies [1,2]. In addition, a detailed description of the treatment of radiative processes is also given (Sec. 4).

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On the role of the II(1/2g) state in spontaneous dissociation of krypton and xenon dimer ions

Cited by 12 publications

References 32 publications

On the Size and Structure of Helium Snowballs Formed around Charged Atoms and Clusters of Noble Gases

On the Size and Structure of Helium Snowballs Formed around Charged Atoms and Clusters of Noble Gases

Formation of even-numbered hydrogen cluster cations in ultracold helium droplets

Multiscale non-adiabatic dynamics with radiative decay, case study on the post-ionization fragmentation of rare-gas tetramers

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