Laboratory EXAFS in a dispersive mode

A laboratory dispersive mode spectrometer, capable of operating in either the analysing crystal transmission mode or a reflection mode, is described. Extended X-ray absorption fine structure (EXAFS) spectra of Re and ReO₂, obtained in the transmission mode, compare favourably with those from a scanning spectrometer at a synchrotron source. Factors affecting resolution, intensity and background in this transmission mode are discussed. Experiments with asymmetric reflection geometries, which have shown both improved resolution for X-ray absorption near edge structure (XANES) and reduced collection times, are reported. Methods of reducing backgrounds due to multiple Bragg reflections and Compton scattering are proposed.