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The surface photo-voltage (SPV) effect and its temporal profile on a Cr/p-GaAs(100) surface were measured by core-level photoelectron spectroscopy with the combination of synchrotron radiation and laser. It was found that the SPV value at the Cr thickness of 0.05 and 0.1 nm is enhanced in comparison with the clean surface, while that at the Cr thickness larger than 0.2 nm is remarkably suppressed. The dependence on the Cr thickness can be interpreted in terms of the change in the band bending and the escape process, which are associated with the electronic structures induced by the Cr deposition. [ABSTRACT FROM AUTHOR]

The valence electronic structures of the dental gold alloys, type 1, type 3, and K14, and their interaction with L-cysteine have been studied by ultraviolet photoelectron spectroscopy with synchrotron radiation. It was found that the electronic structures of the type-1 and type-3 dental alloys are similar to that of polycrystalline Au, while that of the K14 dental alloy is much affected by Cu. The peak shift and the change in shape due to alloying are observed in all the dental alloys. It is suggested that the new peak observed around 2 eV for the L-cysteine thin films on all the dental alloys may be due to the bonding of S 3sp orbitals with the dental alloy surfaces, and the Cu-S bond, as well as the Au-S and Au-O bonds, may cause the change in the electronic structure of the L-cysteine on the alloys. [ABSTRACT FROM AUTHOR]

Photoelectric emission from organic and metal thin films is generally observed with irradiation of photon energy larger than 4 eV. In this paper, however, we report photoelectric emission from Ag on a zinc-phthalocyanine (ZnPc) layer at a photon energy of 3.4 eV. The threshold energy for this photoelectric emission is much smaller than the work function of Ag estimated by conventional photoelectron spectroscopy. The photoelectric emission by low-energy photons is significant for Ag thicknesses of less than 1 nm. Photoelectron spectroscopy and morphological study of the Ag/ZnPc suggest that the anomalous photoelectric emission from the Ag surface is caused by a vacuum level shift at the Ag/ZnPc interface and by surface plasmons of the Ag nanoparticles. [ABSTRACT FROM AUTHOR]

We have performed angle-resolved two-photon photoemission (AR-2PPE) measurements of Bi thin film with the thickness of 12 bilayers grown on Si(111) surface. From the excitation photon-energy dependence of AR-2PPE spectra, we have obtained the energy dispersion of unoccupied electronic states in the energy range between 2.0 and 3.0 eV above the EF. The observed electronic states are attributed to the unoccupied quantum-well states due to quantization of the 6 p-derived bulk bands along the Γ-T direction. [ABSTRACT FROM AUTHOR]

The valence electronic structure of p-type β-FeSi2 single crystal has been investigated by high-resolution and resonant photoelectron spectroscopy using synchrotron radiation. In the photoelectron spectrum at hν = 130 eV, the valence band has a prominent peak at the binding energy (EBin) of 0.5 eV and the valence band maximum almost touches the Fermi level, reflecting the p-type nature. Upon the excitation of Fe2p3/2 core level, the valence-band top at EBin = 0.5 eV exhibits an interference-like resonant behavior clearly shown by a constant-initial-state spectrum. These results are the direct experimental evidences that the valence-band top consists mainly of Fe3d orbitals. [ABSTRACT FROM AUTHOR]

The electronic structure of the silver-based dental alloy MC12 and its constituent metals and their interaction with l-cysteine have been investigated by ultraviolet photoelectron spectroscopy (UPS) using synchrotron radiation. The UPS spectra of l-cysteine on polycrystalline Ag, Cu, Pd, and Au substrates have been measured to understand the interaction of l-cysteine with the dental alloy surface. It was found that the electronic states of MC12 originate dominantly from Cu 3d states and Pd 4d states around the top of the valence bands, while the 4-7-eV electronic structure of MC12 originates from the Ag 4 d5/2 and Ag 4 d3/2 states. For l-cysteine, it was found that a new peak at 2 eV is observed for the thin films on Ag, Cu, and Au, while the structure around 2 eV on MC12 is similar to that on Pd. The shift of the 5-eV peak is observed for the thin films on Cu, Pd, and Au, but not on Ag and MC12. These results indicate that the interaction of l-cysteine with MC12 may be dominantly due to the Pd-S, Cu-S, and Ag-O bonds, while the contribution of the Ag-S bond is small. [ABSTRACT FROM AUTHOR]