Photodissociation of mono- and di-anionic tin clusters
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THE EUROPEAN PHYSICAL JOURNAL D
Regular Article
Photodissociation of mono- and di-anionic tin clusters? Markus Wolframa , Steffi Bandelow, Alexander Jankowski, Stephan K¨onig, Gerrit Marx, and Lutz Schweikhard Institute of Physics, University of Greifswald, Greifswald, Germany Received 4 December 2019 / Received in final form 27 March 2020 Published online 25 June 2020 c The Author(s) 2020. This article is published with open access at Springerlink.com
Abstract. Negatively charged tin clusters offer a broad range of decay products, as observed after electroncluster interactions [S. K¨ onig, M. Wolfram, S. Bandelow, G. Marx, L. Schweikhard, Eur. Phys. J. D 72, 153 (2018)]. To get further insight into their decay pathways, size and charge-state selected clusters Sn− n and Sn2− n were photo-excited at the ClusterTrap setup by 532 nm Nd:YAG laser pulses. For small mono− anionic precursor clusters containing up to n ' 45 atoms, Sn− n−7 and Snn−10 are observed as preferred ionic fragments. For bigger clusters a transition to neutral monomer evaporation was found. In the case of − di-anionic precursors, preferred decay products are Sn− 10 and Snn−10 , indicating fission similar to the case of the group 14 neighbor element lead [S. K¨ onig, A. Jankowski, G. Marx, L. Schweikhard, M. Wolfram, Phys. Rev. Lett. 120, 163001 (2018)]. Furthermore, doubly charged fragment clusters such as Sn2− n−7 are observed, originating from break-off of neutral heptamers Sn7 , a behavior which has not been observed previously for di-anionic clusters.
1 Introduction The group 14 elements (C, Si, Ge, Sn, and Pb) show a significant variation in bulk-phase properties, reflecting their different structures and bonding characteristics. In contrast to semiconducting silicon and germanium, bulk tin is metallic under ambient conditions with a tetragonal lattice structure. However, below 286 K the semiconducting covalently bound Sn (cubic diamond) is the thermodynamically most stable allotrope. The large variation of different structures and bonding characteristics holds true not only for the bulk-phases property, but also for the atomic clusters. The question, whether ligand-free tin clusters should be classified as metallic or semiconducting, motivated several experimental [1–3] and theoretical [3–5] studies. Singly charged tin cluster anions have been investigated by photoelectron spectroscopy [6–8]. Based on such measurements Wang and coworkers assigned a nonmetal-to-metal − transition between Sn− 41 and Sn42 [9]. In addition, several theoretical investigations focused on the geometric structures of small tin cluster anions [10,11]. The other clusters of the group 14 show similar fragmentation behavior: they break into bigger fragment clusters instead of evaporating monomers [12]. Singly positive charged silicon and germanium clusters break into charged clusters of size n = 6–11 or break off neutral heptamers and decamers [13–16]. For lead clusters, on the other hand, besides heptamer ?
Contribution to the Topical Issue “Atomic Cluster Collisio
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