Abstract :
In the present communication, we discuss the results of an angle resolved photoemission extended fine structure
ARPEFS.study of a VO2monolayer ML.grown on the TiO2 110.surface by successive cycles of sub-ML vanadium
metal deposition followed by annealing at 473 K in 2=10y6 mbar O2. The V 3p photoemission peak shows two distinct
components chemically shifted by 1.3 eV. While the higher binding energy BE.component produces a rather flat ARPEFS
curve, the lower BE signal, associated with the VO2 phase, shows well defined intensity modulations whose main features
are similar to the ARPEFS scan on the Ti 3p signal of the substrate. This observation demonstrates that the ordered VO2
phase grows epitaxially to the substrate, with a rutile type structure. However, some oxide is present in a more highly
oxidized and less-ordered phase. In order to investigate the actual arrangement of the ML with respect to the question related
to the possible formation of an intermixed VO2rTiO2layer, the ARPEFS data have been interpreted by means of
single-scattering spherical wave SSC-SW.simulations. They are compatible with the hypothesis that the deposited ML
evolves toward an intermixed VO2rTiO2double layer where the vanadium atoms occupy the six-fold oxygen-coordinated
sites. In addition, our data are in good agreement with a surface relaxation similar to that found by surface XRD on the
stoichiometric TiO2 110.surface. q1999 Elsevier Science B.V. All rights reserved
