Site-specific excitation and decay processes inXeArNclusters

Time- and energy-resolved fluorescence methods with synchrotron radiation excitation are used to investigate excitation and decay processes of electronically excited ${\mathrm{XeAr}}_{\mathit{N}}$ clusters (N=20–5000). For excitations related to the first resonance transition of Xe, pronounced size and site effects are reported. In particular, three distinct sites of atomic Xe are established. Selective excitation of Xe on top of the cluster surface results in an escape of the electronically excited atom, whereas Xe atoms initially located in the interior of the cluster remain after electronic excitation in interior of the cluster.