ABSTRACT
The electronic structure of TiO(2) nanosheets on the Pt(110)-(1 × 2) surface has been investigated by using high resolution photoemission spectroscopy and x-ray absorption spectroscopy (XAS). The Ti 2p XAS spectra of the deposited TiO(2) films have been theoretically evaluated and, from the comparison with the experimental data, the assignment to a lepidocrocite-like structure is confirmed. Coexistence of TiO(2) islands with PtO(2) stripes for incomplete nanosheets is confirmed by high resolution photoemission data. The location of the valence and conduction band edges of the nanosheet has been experimentally determined allowing us to describe in details subtle electronic effects due to the interface with the substrate. The locations of the valence band maximum and the leading peak in the O 1s XAS spectrum indicate a band gap similar to anatase but with the Fermi level closer to mid-gap than found for bulk, n-type TiO(2).
Subject(s)
Ferric Compounds/chemistry , Nanostructures/chemistry , Platinum/chemistry , Titanium/chemistry , Photoelectron Spectroscopy , Surface Properties , X-Ray Absorption SpectroscopyABSTRACT
Methylamine adsorption on the ordered Ni(3)Al(111) and NiAl(110) surfaces has been investigated by high resolution photoelectron spectroscopy and density functional theory calculations. Methylamine adsorbs molecularly at both surfaces at low temperature (90 K). The experiments show that methylamine interacts with the surface aluminium atoms on both surfaces, resulting in a positive binding energy shift relative to the Al 2p bulk contributions. A shift towards lower binding energy is also observed on NiAl(110) attributed to first and second layer surface Al atoms not bonded to methylamine. According to total energy calculations methylamine binds through its N atom to Al on-top sites on NiAl(110) while the Ni on-top site is found to be slightly preferred over the Al on-top site on Ni(3)Al(111). Calculated adsorbate induced shifts are, however, in good agreement with the experimental values only when methylamine is situated in the Al on-top site on both surfaces. In both cases, a lone pair bonding mechanism is found.
