Electron energy loss near edge structure (ELNES), a potential technique in the studies of local atomic arrangements

Abstract

The electron energy loss near-edge structure of the K-edge of Mg and Al octahedrally coordinated by oxygen shows, in all the six cases studied, a similar prominent 8–10 eV broad Gaussian-like peak at the threshold. In none of the three cases where Mg and Al are tetrahedrally coordinated is such a peak observed. For tetrahedrally coordinated Si a much narrower, less than 4 eV, peak is present. These empirical rules have been applied to the studies of mica during the rearrangement process caused by radiation damage. The studies indicate that a considerable fraction of the Al atoms are neither in perfect octahedral nor in perfect tetrahedral positions after the micas have become amorphous, whereas there is no indication of a change in the local symmetry of Si. The appearance of a small peak below the threshold of the K-edge of oxygen is interpreted as due to a valency of oxygen between zero and -2 occurring for a short period of time.