QUASIKINEMATIC LOW-ENERGY ELECTRON-DIFFRACTION SURFACE CRYSTALLOGRAPHY

Based on the idea of constant-momentum-transfer averaging (CMTA) of Lagally et al. and facing the problem of CMTA pointed out by Pendry, in the present work we propose the use of the quasikinematic low-energy electron-diffraction (QKLEED) calculations in comparison with the experimental CMTA curves in surface structure determinations. In QKLEED, the influences of the zero-angle scattering on the CMTA curves are treated so that they have essentially no influence on correctly determining the structural parameters, and the mean complex atomic scattering factors are introduced as the effective scattering factors. In addition, an experimental design is proposed for obtaining CMTA curves containing the least influence of multiple scattering. The whole QKLEED/CMTA method has been carefully and systematically tested, and its capability of determining surface structures is demonstrated on the Cu(001)(1X1), Si(111)(root 3X root 3)R30 degrees-Al, and Si(lll)(root 3X root 3)R30 degrees-Ag surfaces.