He-beam scattering study of the dynamics of oxygen induced reconstruction of the Pt(997) surface: II. Shape changes of the He diffraction patterns induced by reconstruction and oxygen adsorption

Abstract

The changes induced in the shape of the He diffraction patterns by the reconstruction of the Pt(997) surface reflect the presence of terraces with increased width. The locations of the fractional order peaks in the He patterns indicate that the distribution of the terrace widths on the reconstructed surface is more complicated than it was inferred from LEED patterns. The changes of the He diffraction patterns of both, reconstructed and non-reconstructed surfaces, induced by oxygen adsorption are 2-fold: a dramatic shape deformation and an overall reduction of the coherent intensity. The first is shown to be due to oxygen chemisorbed at step sites, while the second mainly to oxygen chemisorbed at terrace sites. Evidence for the important role played by the attractive interaction potential around step edges in He scattering is presented.