Investigation of the oxidized (001) tungsten surface by means of ILEED

Abstract

Inelastic low energy electron diffraction (ILEED) effects have been applied to investigate the initial stages of oxidation on a (001) oriented single tungsten crystal. The electron energy loss spectra (EELS) have been measured as a function of the primary electron energy, E p. The energy was kept within the range: 45 eV < E p < 100 eV. To show the diffraction effect after loss we have used the kinetic model. The electron intensity, I = I( E), integrated over a ring input slit of a CMA, has been calculated as a function of the kinetic energy. The calculation has been performed in the k vector representation. The experimental and the theoretical results have been compared and shown to be in quantitative agreement with each other. A set of EEL spectra measured as a function of E p for the tungsten surface covered with a monolayer of oxide has shown the diffraction effect which was adequate to a (2 × 1) structure of an overlayer. As a result of the band transition investigation an agreement with some features of electronic structure of WO 3 has been found. The peaks at 4.0 eV and 7.2 eV observed in experimental EEL spectrum at E p = 55 eV are also present in a simulated EEL spectrum based on the density-of-states (DOS) function calculated for WO 3.