A LEED-AES study of the oxidation of cr(110) and Cr(100)

The initial stages of the oxidation of (110) and (100) chromium surfaces have been studied using low energy electron diffraction and Auger electron spectroscopy. The low energy Auger electron peaks were tentatively explained in terms of different chemical states. Thus, the clean chromium surface, the surface covered by chemisorbed oxygen and the chromium oxide surface could be associated with the occurrence of different peaks. The intermediate oxygen chemisorption structures observed at oxidation, have been characterized with respect to symmetry and accurate unit cell dimensions. Lattice parameters were found to range from those of the substrate chromium metal to those of chromium sesquioxide. On the (110) face, the lattice parameter change was observed to be largest in the [11̄0] direction. The observations are in fair agreement with current concepts of misfitting crystalline surface layers.