INTERPRETATION OF KINETICS OF IRON SURFACE OXIDATION INVOLVING THE REAL STRUCTURE OF SINGLE-CRYSTAL SAMPLES

The kinetics of oxidation of iron surface has been studied by AES meth od. The effects of oxygen diffusion into the lattice defects have been considered in the discussion of the mechanism of the oxygen adsorptio n. The real sticking coefficient has been determined as a function of oxygen coverage (S = 1-theta in the range of 0 < theta < 0.9). The oxi dation of iron surface occurs in two steps. At the first step the diss ociative oxygen adsorption occurs for the coverage 0 < theta(circle) < 1 and the rate of the oxygen molecule adsorption is limiting. At the second step, in the range of oxygen coverage 1 < theta(circle) < 2, th e reconstruction of the iron surface occurs with the formation of free adsorption sites. At this step the sticking coefficient of oxygen is almost constant (S almost-equal-to 0.1).