Orientation dependence of ionization edges in EELS

Anisotropy in the density of unoccupied states can be detected in the fine structure of ionization edges in angle-resolved EELS. It is shown that in a crystal an interference term occurs in the inelastic signal, and how it re lates to electron channeling and site selection. The combination of orienta tion and site selection induces subtle variations in the ELNES. It is shown how this technique can be used to analyze local anisotropy related to the point group of the target atom. A second example shows how to extract non-d ipole transitions at small scattering angles. (C) 2001 Elsevier Science B.V . All rights reserved.