Near neighbor separations of surface atoms. Progress report

Abstract

The construction phase of the work to develop a technique to measure near-neighbor distances of low-Z atoms that are adsorbed at solid surfaces is nearly complete. The instrument will measure EXAFS-like variations that are associated with core-level loss features in the secondary yield of high-energy electrons. The goal is to then combine the knowledge of these spacings with analysis of electron diffraction data to determine the structure of surfaces. The apparatus that was constructed is described. It became apparent in the course of this work that the instrument would also be well suited for reflection high-energy electron diffraction (RHEED), and therefore the applicability of RHEED to studies of surface structure was investigated. Exploratory measurements were made on an existing RHEED system that was available. The conclusion is that RHEED is ideally suited to study the distribution of steps on surfaces.