Electron Impact Fragmentation of Size-Selected Krypton Clusters

Steinbach, C.; Fárnı́k, Michal; Buck, U.; Brindle, Carrie A.; Janda, Kenneth C.

doi:10.1021/jp0626061

Cited by 14 publications

(16 citation statements)

References 28 publications

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“…In the experiments by Buck and co-workers, 38,70,71 bare Ng clusters were directly ionized by electrons, whereas in our experiments Ng clusters are embedded in helium droplets and ionized indirectly by charge transfer from He + . 72−74 Still, experiments by Janda and co-workers suggest that these different experimental approaches both show the same striking difference in the fragmentation behavior between heavy Ng clusters and argon clusters.…”

Section: Resultscontrasting

confidence: 52%

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: Resultscontrasting

confidence: 52%

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

et al. 2013

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“…An experimental study has recently been conducted 45 on the fragmentation of size-selected neutral krypton clusters induced by electron impact ionization by Steinbach et al A preliminary analysis of the results shows extensive fragmentation and the appearance of Kr 3 + fragments at the same size as in our simulation. A detailed comparison will be performed in the near future.…”

mentioning

confidence: 58%

“…Very recently, new experiments have been undertaken 45 by Steinbach et al to determine the results of the fragmentation dynamics of krypton clusters following electron impact ionization. This type of experiments has been used in the past by Buck and co-workers to determine the fragmentation pattern of argon clusters following electron impact ionization.…”

Section: B Comparison With Size-selected Neutral Experiments: Role Omentioning

confidence: 99%

Modelization of the fragmentation dynamics of krypton clusters (Krn,n=2–11) following electron impact ionization

Bonhommeau

Bouissou

Halberstadt

et al. 2006

The Journal of Chemical Physics

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We present the first prediction for the fragmentation dynamics following electron impact ionization of neutral krypton clusters from 2 to 11 atoms. Fragment proportions and parent ion lifetimes are deduced from a molecular dynamics with quantum transitions study in which the nuclei are treated classically and the transitions between electronic states quantum mechanically. The potential-energy surfaces are derived from a diatomics-in-molecules model to which induced dipole-induced dipole and spin-orbit interactions are added. The results show surprisingly fast and extensive fragmentation for clusters of such a heavy atom, although not as extensive as in the case of neon clusters studied previously [D. Bonhommeau et al., J. Chem. Phys. 123, 54316 (2005)]. The parent ion lifetimes range from 2.8 to 0.7 ps, and the most abundant fragment is Kr(2) (+) for all studied sizes, followed by Kr(+) for sizes smaller than 7 atoms and by Kr(3) (+) for larger sizes. Trimer and larger fragments are found to originate from the lower electronic states of parent ions. The comparison with preliminary results from experiments on size-selected neutral clusters conducted by Steinbach et al. (private communication) reveal a good agreement on the extensive character of the fragmentation. It is checked that the additional internal energy brought by the helium scattering technique used for size selection does not affect the fragment proportions. In addition, the existence of long-lived trajectories is revealed, and they are found to be more and more important for larger cluster sizes and to favor the stabilization of larger fragments. The implications of this work for microsecond-scale dynamics of ionized rare-gas clusters are discussed. In particular, given the extent of fragmentation of the parent clusters and the fast kinetics of the whole process, the small cluster ions that exhibit a monomer loss in the microsecond time window must originate from much larger neutral precursors. The decay rate of the II(12)(u) state of the ionic dimer Kr(2) (+) by spin-orbit coupling is found to be of the order of 3 ps, in contrast to the expected tens of microseconds, but only reasonably faster than the corresponding state of HeNe(+). Finally, the spin-orbit interaction strongly affects both the Kr(+)Kr(2) (+) ratio and some of the characteristic times of the dynamics, especially for smaller sizes, but not the overall dependence of the fragment proportions as a function of cluster size.

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“…The post-ionization fragmentation of rare-gas clusters has for long been a matter of controversy between theory and experiment, in particular for heavier rare gases (krypton and xenon). While, for these two heavy rare gases, experiment predicted an absolute dominance of monomer ionic fragments resulting from ionized parents decay [68,69], in theory [70,69] ionic dimers dominated for small parent sizes or even larger ionic fragments as the parent size increased. For lighter rare-gases (argon and neon), on the other hand, the agreement between theory and experiment was rather satisfactory [39,71].…”

Section: Post-ionization Fragmentationmentioning

confidence: 99%

Non-adiabatic dynamics combining Ehrenfest, decoherence, and multiscale approaches applied to ionic rare-gas clusters photodissociation, post-ionization fragmentation, and collisions

Kalus

Janeček

Gadéa

2019

Computational and Theoretical Chemistry

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Electron Impact Fragmentation of Size-Selected Krypton Clusters

Cited by 14 publications

References 28 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

Modelization of the fragmentation dynamics of krypton clusters (Krn,n=2–11) following electron impact ionization

Non-adiabatic dynamics combining Ehrenfest, decoherence, and multiscale approaches applied to ionic rare-gas clusters photodissociation, post-ionization fragmentation, and collisions

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