AL L-CORE EDGE PINE STRUCTURE IN AL, ALN AND ALPHA-AL2O3 - A COMPARISON OF MICROELECTRON ENERGY-LOSS SPECTRA WITH THEORY

The Al L near-edge fine structures of aluminum and its compounds with nitrogen and oxygen are studied using electron energy loss microspectr oscopy in a transmission electron microscope. These edges are normaliz ed to the same scattering cross section per Al atom per electronvolt. The cross section is calculated by using the Born approximation. The c ontributions to the cross section are from the valence shell crystal s tates obtained by using the extended Huckel band calculation and the i onization states obtained by using the electron gas model. The chemica l effects in the ionization region are taken into account by including the contributions from the elastic backscattering of outgoing plane w aves by the atoms that neighbor the excited atoms. The results by theo retical calculation agree semiquantitatively with experimental results .