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arXiv · 0902.4713

Alkali-helium snowball complexes formed on helium nanodroplets

S. Muller·M. Mudrich·F. Stienkemeier
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Abstract

We systematically investigate the formation and stability of snowballs formed by femtosecond photo-ionization of small alkali clusters bound to helium nanodroplets. For all studied alkali species Ak=(Na, K, Rb, Cs) we observe the formation of snowballs (AkHe_N)^+ when multiply doping the droplets. Fragmentation of clusters Ak_N upon ionization appears to enhance snowball formation. In the case of Na and Cs we also detect snowballs (Ak_2He_N)^+ formed around Ak dimer ions. While the snowball progression for Na and K is limited to less than 11 helium atoms, the heavier atoms Rb and Cs feature wide distributions at least up to (AkHe_41)^+. Characteristic steps in the mass spectra of Cs-doped helium droplets are found at positions consistent with predictions on the closure of the 1st shell of helium atoms around the Ak^+ ion based on variational Monte Carlo simulations.

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S. Muller, M. Mudrich, F. Stienkemeier. 2009-02-26. Alkali-helium snowball complexes formed on helium nanodroplets. https://doi.org/10.1063/1.3180819

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