The use of the X-ray absorption near edge spectrum in materials characterisation

The increasing availability and use of synchrotron radiation has opened up new horizons in materials research. These sources offer very high brightness photon probes in an unparalleled wavelength range from the UV to the hard X-ray region. Although the medium to hard energy extended X-ray absorption fine structure (EXAFS) has been widely used in materials characterisation, the near edge absorption spectrum (XANES), especially in the soft X-ray region below 2 kV, has been exploited to only a limited degree. This relates to both the difficulties and limited availability of soft X-ray monochromators and the complexity of the spectra relative to the EXAFS region. We have used XANES in studies of semiconductor oxide and nitride materials, the speciation of sulfur in industrial smelting anodes and the development of oxide based electrode materials for Li ion batteries. Although of limited quantitative applicability, the chemical detail available in these spectra is considerably superior to that in the X-ray photoelectron (XPS) spectrum and demonstrates the considerable power of the method.