The continuous-time core-level photon-stimulated desorption (PSD) spectroscopy was employed to monitor the monochromatic soft x-ray-induced reactions of C F3 Cl adsorbed on Si (111) -7×7 near the F (1s) edge (681-704 eV). Sequential F+ PSD spectra were measured as a function of photon exposure at the C F3 Cl -covered surface (dose=0.3× 1015 molecules cm2, ∼0.75 ML). The F+ PSD and total electron yield (TEY) spectra of molecular solid C F3 Cl near the F (1s) edge were also measured. Both F+ PSD and TEY spectra show two features at the energy positions of 690.2 and 692.6 eV, and are attributed to the excitations of F (1s) to 11 a1 [(C-Cl)*] and (8e+12 a1) [(C-F)*] antibonding orbitals, respectively. Following Auger decay, two holes are created in the F (2p) lone pair and/or C-F bonding orbitals forming the 2h1e final state which leads to the F+ desorption. This PSD mechanism, which is responsible for the F+ PSD of solid C F3 Cl, is employed to interpret the first F+ PSD spectrum in the sequential F+ PSD spectra. The variation of spectrum shapes in the sequential F+ PSD spectra indicates the dissipation of adsorbed C F3 Cl molecules and the formation of surface SiF species as a function of photon exposure. From the sequential F+ PSD spectra the photolysis cross section of the adsorbed C F3 Cl molecules by photons with varying energy (681-704 eV) is determined to be ∼1.0× 10-17 cm2.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry