Visualizing sulfur with X-rays: From molecules to tissues

Abstract

Sulfur is sometimes called a spectroscopically silent element because there are so few tools for probing its chemistry. This paper will review how sulfur K-edge X-ray absorption spectroscopy and related methods can be used to overcome this limitation, using examples from the authors’ research. X-rays from synchrotron radiation sources provide the means to study essentially any element in a variety of systems, ranging from pure compounds, to complex mixtures and even structured systems such as biological tissues. We show that sulfur K-edge X-ray absorption spectroscopy provides an important spectroscopic probe of sulfur chemistry in a range of systems, including those containing reactive species. Using a micro-focused X-ray beam, chemically-dependent X-ray fluorescence imaging can be used to image different sulfur species at a variety of spatial resolutions from microscopic to macroscopic. Increased sensitivity and deeper insights into electronic structure will be available in future studies using a suite of methods that are collectively known as advanced X-ray spectroscopy.

Graphical abstract

Keywords:

• Sulfur
• speciation
• X-ray absorption spectroscopy
• X-ray fluorescence imaging
• advanced X-ray spectroscopy

Acknowledgements

EYS was supported by a grant from the NIH (GM57375, to GNG & IJP). EB was supported by a grant from the NSF (CHE-1265679). Research at the University of Saskatchewan is supported by grants from NSERC, SHRF, CIHR (GNG & IJP) and by Canada Research Chairs (GNG & IJP). Chevron Energy Technology Company (GNG, IJP). Use of the Stanford Synchrotron Radiation Lightsource (SSRL) is supported by the U.S. DOE. The SSRL Structural Molecular Biology Program is supported by the DOE OBER, and by the NIH, NIGMS (P41GM103393). The contents of this publication are solely the responsibility of the authors and do not necessarily represent the official views of NIGMS or NIH.