STRUCTURAL STUDY OF THIN-FILMS BY EXTENDED ENERGY-LOSS FINE-STRUCTURE SPECTROSCOPY

The extended energy loss fine-structure (EELFS) technique, using low kinetic energy electrons in the reflection geometry, has proved to be a valuable tool for short-range order investigation of both clean surfaces and surfaces covered by different overlayers. The most attractive aspect of this technique is that the interpretation and the analysis of the features observed above the ionization core edges follows the procedure and the theoretical scheme used for extended X-ray absorption fine-structure spectroscopy to obtain the local structural parameters. The focal point underlying the EELFS analysis is to assume that the dipole approximation is valid. This approximation is generally well accepted for transmission energy loss experiments while its use should be questionable for spectra performed in the reflection scattering mode because the energy of the primary electron beam is comparable with the observed energy loss. In this work we review some recent applications and theoretical considerations of the EELFS technique to give local structural parameters of continuous and discontinuous films.