The geometric structure of pure SF6 and mixed Ar/SF6 clusters investigated by core level photoelectron spectroscopy

The S 2p core level photoelectron spectra of Sulphurhexafluoride clusters have been investigated together with heterogeneous Ar/SF6 clusters, created by doping Ar host clusters (with a mean size of 3600 atoms) with the molecule. Surface and bulk features are resolved both in the argon 2p and the sulphur 2p core level photoelectron spectra. For the latter level such features were only observed in the pure cluster case; a single feature characterizes the S 2p core level spectra of SF6 doped argon clusters. From the chemical shifts, investigated with respect to SF6 doping pressure. It can be concluded that the host clusters get smaller with increasing doping pressures and that the SF6 molecules predominantly stay below the cluster surface, whereas the Argon core stays intact. We have neither observed features corresponding to SF6 on the cluster surface, nor features corresponding to molecules deep inside the bulk in any of the spectra from the pick-up experiments.