X-ray Absorption Spectroscopy as Tool for the Detection and Identification of Sulfur Compounds in Phototrophic Organisms

Abstract

X-ray absorption spectroscopy (XAS) is an in situ technique which combines the advantages of a local probe technique with the high penetration strength inherent to X-rays, such as no need for long range order and the ability to obtain information on selected sites of a given sample only. Therefore, this technique is applicable to a broad variety of scientific topics, including many applications to elucidate the chemical speciation of sulfur in phototrophic organisms. The first part of the chapter provides an elementary introduction to the physical background and method, whose application to a broad variety of problems is discussed in detail, followed by detailed examples and explanations on X-ray absorption near edge structure (XANES) measurements of sulfur compounds. In the second part, examples of successful applications of XANES analyses of bacterial sulfur globules of purple and green sulfur bacteria, the wheat gluten network, and sulfur in host–plant interactions are presented.