RESUMO
The bonding structure of nitric oxide (NO) on Cu(110) is studied by means of scanning tunneling microscopy, reflection absorption infrared spectroscopy, and electron energy loss spectroscopy at 6-160 K. At low temperatures, the NO molecule adsorbs at the short bridge site via the N end in an upright configuration. At around 50 K, this turns into a flat configuration, in which both the N and O atoms interact with the surface. The flat configuration is characterized by the low-frequency N-O stretching mode at 855 cm(-1). The flat-lying NO flips back and forth when the temperature increases to ~80 K, and eventually dissociates at ~160 K. We propose a potential energy diagram for the conversion of NO on the surface.
RESUMO
From the analysis of high-resolution Si 2p photoelectron and near-edge x-ray absorption fine structure (NEXAFS) spectra, we show that core level excitations of epitaxial silicene on ZrB2(0001) thin films are characteristically different from those of sp(3)-hybridized silicon. In particular, it is revealed that the lower Si 2p binding energies and the low onset in the NEXAFS spectra as well as the occurrence of satellite features in the core level spectra are attributed to the screening by low-energy valence electrons and interband transitions between π bands, respectively. The analysis of observed Si 2p intensities related to chemically distinct Si atoms indicates the presence of at least one previously unidentified component. The presence of this component suggests that the observation of stress-related stripe domains in scanning tunnelling microscopy images is intrinsically linked to the relaxation of Si atoms away from energetically unfavourable positions.
