Soft X-ray Spectroscopic Characterization of Montmorillonite

Abstract

AbstractSoft X-ray spectroscopy was applied to study a calcium bentonite from the Kutch area in India. We recorded the X-ray absorption spectra from the L-edge of calcium, silicon, and aluminum, and from K-edge of oxygen. The Ca absorption spectrum shows a quasi-atomic behavior, while the Si spectrum closely simulates the absorption spectrum of a pure silicon oxide. The O K spectrum shows a pre-peak, which is absent in the spectra of both the pure, bulk aluminum and silicon oxides. The Al L spectrum is complex and shows almost no resemblance to the absorption spectrum of aluminum oxides. The chemical state of the Al atoms (in octahedral coordination) must, thus, be quite different from what is common in the oxides. The obtained data show that soft X-ray spectroscopy is a promising technique for studying clay minerals. It is capable of supplying unique information that is complementary to information accessible using other techniques; especially, it can be used to determine the local electronic structure at various atomic sites in the complex samples.