Search

Unoccupied and occupied electronic structures of an L-cysteine film have been studied by absorption and resonant photoelectron spectroscopies. Core absorptions at S-L, C-K, N-K, and O-K levels indicate that the lower unoccupied states are predominantly composed of oxygen-2p, carbon-2p, and sulfur-4s+3d orbitals, while higher unoccupied states may be attributed dominantly to nitrogen-np (n ≥ 3), oxygen-np (n ≥ 3), and sulfur-ns+md (n ≥ 4, m ≥ 3) orbitals. Resonant photoelectron spectra at S-L23 and O-K levels indicate that the highest occupied state is originated from sulfur-3sp orbitals, while oxygen-2sp orbitals contribute to the deeper valence states. The delocalization lifetimes of the oxygen-1s and sulfur-2p excited states are estimated from a core-hole clock method to be about 9 ± 1 and 125 ± 25 fs, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Valence electronic structure of - single crystal has been investigated by photoelectron spectroscopy using synchrotron radiation. The plate-type - single crystal has been grown by chemical vapor transport method. The surface contamination and oxide layer were removed by Ne+ ion sputtering. The dependence of the valence band spectra on exciting photon energy shows that the strong peak at the binging energy () of 0.5 eV and the shoulder peak at  eV are assigned to be and orbitals, respectively. Upon the excitation of , resonant enhancement of the valence band was observed at  eV, which is very similar to Fe metal. This fact suggests the existence of the two-hole satellite states from orbitals. [Copyright &y& Elsevier]

The adsorption and reaction of silver on an oxidized Si(0 0 1) surface were investigated on the basis of Si 2p, Ag 3d and O 1s core-level photoemission measurements at room temperature (RT). We compared the present results with those obtained in the case of titanium in our previous study. We found that silver on an oxidized Si(0 0 1) surface at RT causes a reduction in the intensity of the Si 1+ and Si 2+ states and an increase in the intensity of the Si 3+ and Si 4+ states. Based on an analysis of the Ag 3d and O 1s states, we concluded that the change in the Si 2p oxidized states upon silver adsorption is due to charge transfer rather than conformation change, although the applicability of the charge transfer scheme may be dependent on the thickness of the silver layer. We also deduced that penetration of silver atoms through a thin silicon oxide film occurs. [ABSTRACT FROM AUTHOR]

Highlights: [•] Deposition of titanium on oxidized silicon surfaces. [•] Characterization of oxide thin films on Si surfaces using photoelectron spectroscopy with synchrotron radiation. [•] Chemical shift due to charge transfer. [ABSTRACT FROM AUTHOR]

Abstract: Metal–organic interfaces have been attracting continuous attention in many fields including basic biosciences. The surface of dental alloys could be one of such interfaces since they are used in a circumstance full of organic compounds such as proteins and bacteria. In this work, electronic structures of Au-dominant dental alloys, which have Ag and Cu besides Au, and those of l-cysteine on the dental alloys have been studied by photoelectron spectroscopy with synchrotron radiation. It was found that the density of states in the dental alloy originate from gold and copper as constituents, and the Cu-3d states contribute dominantly to the occupied states near the Fermi level. It was also found that the electronic structure of the l-cysteine thin film on the dental alloy is different from that of the l-cysteine thick film. The result indicates the formation of the orbital bonding between Cu-3d and S-3sp states in the thin film on the dental alloy. [Copyright &y& Elsevier]

Abstract: We investigated Fe films on a negative electron affinity (NEA) O/Cs/GaAs(100) surface by photoelectron spectroscopy and photocurrent measurements. From the results, it is shown that the Fe covered surface retains NEA character, which is comparable to that of the standard NEA, even in the thicker Fe coverage region of about 100Å. It is also found that the change of NEA intensity is independent of the change of the work function. From the core level peak results, it is also discussed that further chemical reaction at the interface and overlayer. [Copyright &y& Elsevier]

A √3×√3-(Pb,Sn) surface was studied by means of scanning tunneling microscopy (STM) and core-level photoelectron spectroscopy (PES) to identify its local atomic arrangement. Observed spots in STM were classified into three types, which were white and gray (α), gray and white (β), and black and gray (γ) spots in the filled- and empty-state images, respectively. The STM images also showed a local 3×3-(Pb,Sn) arrangement in the √3×√3-(Pb,Sn) surface. Both Pb 5d and Sn 4d core-levels spectra indicated that there were two components on the √3×√3-(Pb,Sn) surface, and the peak positions and shapes of Pb 5d and Sn 4d core-levels of the √3×√3-(Pb,Sn) surface were almost the same as those of the √3×√3-Pb and √3×√3-Sn surfaces. Comparison between the heights of the STM spots on the single and binary adsorbate surfaces and their core-levels spectra suggested that Sn and Pb were located at α and β positions, respectively. The nominal coverage of the local 3×3-(Pb,Sn) arrangement was determined to be 1/9 and 2/9 ml for Sn and Pb, respectively. [Copyright &y& Elsevier]