Band structure studies in solids using X-ray spectroscopy

Abstract

The advent of X-ray photoelectron spectrometer and high energy synchroton sources have renewed interest in X-ray spectroscopical investigation of matter, be it solid, liquid or gases. Out of all spectroscopies available for study of electronic structure of material, X-ray spectroscopy has a spectacular contribution like optical spectroscopy and has enriched the knowledge of electronic structure of atoms. molecules and condensed matter. The analysis of X-ray transitions between atomic levels is a very direct method of studying atomic structure and experimental determination of X-ray energy lines give proof to the theoretical models. Thus the spectra from metals, semiconductors and insulators in the form of pure element, alloys and compound provide detail information about the density of states near Fermi level as well as those in the conduction and valence bands. Non-diagrams lines or the satellites provide a lot of information about the quasi states and vacancies between valence and conduction bands. Shift of X-ray emission and absorption lines provide information on the valence of the elements charge associated with it and the bonding present in alloys and compounds. In this short paper, usefulness of X-ray spectroscopic investigation on some metals, alloys, semiconducting thin films and insulating materials is highlighted. Study on these samples have shown the type of bonding present in alloy thin films, charge associated with different atoms, density of states present on the top of valence band and near the Fermi level. Further, the role of Coster-Kronig process of vacancy production, many electron effects and exchange interaction between d and p states are also discussed.