Chemical Bonding Studies of Silicates and Oxides by X-Ray <i>K</i>-Emission Spectroscopy

This paper describes experimental techniques developed for the adaptation of available commercial electron microprobes as convenient and versatile x-ray spectrometers of moderate resolution. Complete K-emission spectra were measured for Mg, Al, and Si, as elements and as selected sixfold- and fourfold-coordinated crystalline oxides. Numerous empirical correlations were indicated by the results. The structures of the Kβ bands of the oxide spectra were interpreted on the basis of their known crystal structures together with elementary molecular orbital theory. In this manner, observed peaks in the Kβ band of each oxide were assigned to specific transitions between valence band orbitals and the inner 1s vacancy. New insight was thereby obtained concerning the contributions of covalent bonding in these oxides.