Chemical selectivity in photon-stimulated desorption of fluorine from silicon

Photon-stimulated desorption of F⁺ from Si(111) was studied with use of photon energies in the region of the Si 2p core level. Fluorinated surfaces with variable amounts of SiFₓ groups were prepared, and distinct photon-stimulated--desorption thresholds in the Si 2p region were observed for F⁺ desorption from SiF vs SiF₃ surface groups. In addition, the angular distributions of the ejected F⁺ showed variations with respect to the Si(111) surface normal dependent on the bonding configuration, which were used to obtain local 2p absorption spectra for the individual SiFₓ groups.