Monochromatic soft X-ray-induced reactions of CCl2F2 adsorbed on Si(111)-7x7 near the Si(2p) edge

Continuous-time photoelectron spectroscopy (PES) and continuous-time core-level photon-stimulated desorption (PSD) spectroscopy were used to study the monochromatic soft X-ray-induced reactions of CCl2F2 molecules adsorbed on Si(111)-7 x 7 at 30 K (CCl2F2 dose = 2.0 x 10(14)molecules/cm(2), similar to 0.75 monolayer) near the Si(2p) core level. Evolution of adsorbed CCl2F2 molecules was monitored by using continuous-time photoelectron spectroscopy at two photon energies of 98 and 120 eV to deduce the photolysis cross section as a function of energy. It was found that the photolysis cross sections for 98 and 120 eV photons are _1.4 x 10(-18) and similar to 8.0 x 10(-18) cm(2), respectively. Sequential F+ PSD spectra obtained by using continuous-time core-level photon-stimulated desorption spectroscopy in the photon energy range of 98-110 eV show the variation of their shapes with photon exposure and depict the formation of surface SiF species. The dissociation of CCl2F2 molecules adsorbed on 51(111)-7 x 7, irradiated by monochromatic soft X-ray in the photon energy range of 98-110 eV, is mainly due to dissociative electron attachment and indirect dipolar dissociation induced by photoelectrons emitted from the silicon surface. (C) 2012 Elsevier B.V. All rights reserved.