X-ray absorption near-edge structure

XANES is a form of atomic adsorption spectroscopy used in chemical analysis. XANES can be used to determine a great deal of chemical information, for example, the formal valence of an atom and its coordination environment. XANES spectra can be used as a probe of the unoccupied band structure of a material. The near-edge structure is characteristic of environment and valence state. In a sample containing a mixture of sites or compounds, the measured spectra can be fit with linear combinations of XANES spectra of known species, and the proportion of each in the sample can be determined. Since X-ray absorption edges of light elements such as C, N, and O are located in soft X-ray region, analysis often must be conducted under high vacuum conditions. This technique has been applied to the characterization of meteoritic organics together with STXM (scanning transmission X-ray microscopy).