Electron transfer reactions on Cs/MoS{sub 2}(0002) with chlorine, oxygen, and water: High resolution x-ray photoelectron spectroscopy and theoretical study
- Zettlemoyer Center for Surface Studies and Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)
Supra-valence electron transfer from surface Cs-doped MoS{sub 2}(0002) to electron acceptor adsorbates was investigated by high resolution x-ray photoelectron spectroscopy (HRXPS) in the valence band region and above the valence band maximum (VBM). Deposition of a sub-monolayer amount of Cs onto the basal plane of MoS{sub 2} introduced a new electron density of states at ca. 1.25 eV above VBM. Angle-resolved HRXPS and theoretical analysis located this electron density in the MoS{sub 2} layer. Upon the reaction with Cl{sub 2}, this Cs-induced photoelectron almost completely disappeared and the Cs 3d and Cl 2p core levels indicated the formation of a surface Cs-chloride species. The Cs-covered MoS{sub 2}(0002) surface also reacted with O{sub 2} to form surface peroxides and superoxides, as evidenced by two distinct binding energies of the O 1s core level peaks. However, the reaction with water proved to be more difficult: Exposure of the Cs-covered MoS{sub 2}(0002) surface to H{sub 2}O at 10{sup {minus}5}&hthinsp;Torr did not result in electron transfer reaction, but the Cs/MoS{sub 2}(0002) surface exposed to H{sub 2}O at 1 Torr showed a substantial decrease in the density of states above VBM as well as formation of a surface-hydroxide, indicated by the O 1s core level position. Theoretical calculations using a full-potential linearized augmented plane wave density functional theory (FLAPW-DFT) confirm the conclusion based on experimental intensity anisotropy of the new peak: the Cs 6s electron transfers into the MoS{sub 2} substrate, forming the Cs/MoS{sub 2} electron donor{endash}acceptor complex with Cs{sup {delta}+}. In addition, all phenomena observed during the adsorption of electron donor{endash}acceptor molecules are quantitatively accounted by the theory. {copyright} {ital 1999 American Institute of Physics.}
- OSTI ID:
- 354517
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 4 Vol. 111; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
Similar Records
Surface structure of single-crystal MoS{sub 2}(0002) and Cs/MoS{sub 2}(0002) by X-ray photoelectron diffraction
Valence-band electronic structure of MoS{sub 2} and Cs/MoS{sub 2}(0002) studied by angle-resolved x-ray photoemission spectroscopy