He-beam scattering study of the dynamics of oxygen induced reconstruction of the Pt(997) surface: I. Dynamics of double step formation and destruction

Abstract

The Pt(997) surface when heated in oxygen environment (5×10⁻⁹−10⁻⁷ mbar) appears to reconstruct in the temperature range 600–900 K. The reconstructed surface is characterized (LEED) by steps of double height. The dynamics of the double step formation and destruction was studied by monitoring the intensity of a fractional order He-diffraction peak, which is characteristic of the reconstructed structure. Oxygen chemisorbed at the double height steps with a binding energy of about $\text{80}\text{kcal}\text{mole}$ plays a determining role in the build-up and stabilization of these steps. The rate determining factor of build-up and decay of the reconstructed surface appears to be, at low temperatures, the self-diffusion of Pt atoms and, at high temperatures, the availability of chemisorbed oxygen.