Structure Determination of Molecular Adsorbates with Large Unit Cells or Lattice-Gas Disorder on Metal Surfaces

摘要

For the purpose of structural determination of molecular adsorbates with large unit cells or lattice-gas disorder on metal surfaces, a novel method was developed to handle multiple scattering of electrons by surfaces. The method is particularly suitable for complex and disordered surfaces. It enables a great increase in computational efficiency for the determination of surface structures. In particular, a method of treating electron scattering by chains of atoms (these chains are to be thought of as components of a surface) was developed. These new methods were applied to the interpretation of experimental data, thereby extracting structural information about simple but non-trivial surfaces. The key to the approach is twofold: first, use kinetic electron energies above a few hundred electron volts, so as to obtain forward focusing by atoms; second, treat the surface as a cluster of atoms without regard to periodicity, thereby allowing complex and disordered surface structures. (AW)