Rostock 2019 – scientific programme
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MO: Fachverband Molekülphysik
MO 4: Electronic Spectroscopy
MO 4.6: Talk
Monday, March 11, 2019, 12:00–12:15, S HS 002 Biologie
Optically-induced collapse of Mg foam in helium nanodroplets — •Lev Kazak1, Sebastian Göde2, Josef Tiggesbäumker1, and Karl-Heinz Meiwes-Broer1 — 1Institute of Physics, University of Rostock, Albert-Einstein-Str. 23-24, 18059 Rostock, Germany — 2European XFEL GmbH, Holzkoppel 4, 22869 Schenefeld, Germany
Magnesium embedded in helium droplets exist in form of metastable network of atoms surrounded by the layer of helium or so-called foam. At the conditions where only one Mg atom is presented in droplet, resonant two-photon ionization spectroscopy in the vicinity of 31P1← 31S0 atomic transition reveals a narrow peak at 279 nm, blue-shifted relative to free atom. When the number of Mg atoms increases, a second peak at 282 nm arise and independent on further change of number of atoms. The presence of this feature, indicates that Mg atoms in He droplet have a interatomic distance of about 10 Å. In present work, the results on photoelectron spectroscopy of activated Mg foam are present. Instead of a single photoemission line, complex photoelectron spectra are obtained when several magnesium atom are present in the droplet, but almost no specific doping dependence is observed. New photoelectron peaks are attributed to highly excited states of Mg atoms. Analysis of electron yield with respect to pick-up statistics reveals the maximum number of Mg atoms which could be stabilized in foam. The behavior of photoelectron spectra indicates a foam collapse. The excess of energy during this process is transferred to single Mg atoms, leading to population of highly excited states.