An X-ray spectroscopy technique, usually synchrotron-based, that provides information on the chemical state and short-range atomic order of the top few microns of a surface. It concerns the conversion of the X-ray energy absorbed by the system to optical photons often involving multi-step cascade processes. XEOL is often used together with XANES/NEXAFS to provide site specificity which in turn can help reveal the electronic structure and optical properties of the system of interest.
