title: Monochromatic soft-x-ray-induced reactions of CF2Cl2 adsorbed on Si(111)-7 × 7 studied by continuous-time photon-stimulated desorption spectroscopy near the F(1s) edge.
abstract: Continuous-time core-level photon-stimulated desorption (PSD) spectroscopy was used to investigate the monochromatic soft x-ray photoreactions of CF(2)Cl(2) adsorbed on Si(111)-7 × 7 near the F(1s) edge (681-704 eV). Sequential F(+) PSD spectra were observed as a function of photon exposure at the CF(2)Cl(2)-covered surface (dose = 2.0 × 10(14) molecules cm(-2), ∼0.75 monolayer). The F(+) PSD and total electron yield (TEY) spectra of solid CF(2)Cl(2) near the F(1s) edge were also measured. Both F(+) PSD and TEY spectra depict three features in the energy range of 687-695 eV, and are assigned to the excitations of F(1s) to (13a(1) + 9b(2))[(C-Cl)(∗)], (7b(1) + 14a(1))[(C-F)∗] antibonding and 5p Rydberg orbitals, respectively. Following the Auger decay process, two holes are created in the C-F bonding orbitals producing the 2h1e final state which results in the F(+) desorption. This PSD mechanism, responsible for the F(+) PSD of solid CF(2)Cl(2), is used to explain the first F(+) PSD spectrum in the sequential F(+) PSD spectra. The variation of spectral shapes in the sequential F(+) PSD spectra shows the consumption of adsorbed CF(2)Cl(2) molecules and the production of surface SiF species as a function of photon exposure. The photolysis cross section of the adsorbed CF(2)Cl(2) molecules by photons with varying energy (681-704 eV) is deduced from the sequential F(+) PSD spectra and found to be ∼6.0 × 10(-18) cm(2).
authors: Department of Physics, National Cheng Kung University, Tainan, Taiwan.
authors: S-K
authors: SK
authors: Wang
authors: W-C
authors: WC
authors: Tsai
authors: L-C
authors: LC
authors: Chou
authors: Y-C
authors: YC
authors: Hsieh
authors: K-H
authors: KH
authors: Chen
authors: T-M
authors: TM
authors: He
authors: K-S
authors: KS
authors: Feng
authors: C-R
authors: CR
authors: Wen
mesh_terms: D000327:Adsorption; D002244:Carbon / Q000737:chemistry; D002627:Chemistry, Physical / Q000379:methods; D002713:Chlorine / Q000737:chemistry; D005617:Chlorofluorocarbons, Methane / Q000737:chemistry*; D004583:Electrons; D005461:Fluorine / Q000737:chemistry; D007477:Ions; D008956:Models, Chemical; D017785:Photons; D012825:Silicon / Q000737:chemistry*; D013053:Spectrophotometry / Q000379:methods*; D013499:Surface Properties; D014965:X-Rays
chemical_list: D005617:Chlorofluorocarbons, Methane; D007477:Ions; D005461:Fluorine; D002713:Chlorine; D002244:Carbon; C007782:dichlorodifluoromethane; D012825:Silicon