THEORY OF EXTENDED X-RAY EMISSION FINE STRUCTURE (EXEFS) Jun Kawai Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan Radiative Auger effect (RAE) is an effect associated with characteristic X-ray emission from an atom. RAE is the shake-up or shake-off process at the electron transition from an outer shell to an inner shell, and is an energy loss process in X-ray emission spectra. Theoretical background of RAE as a novel tool to measure the X-ray absorption fine structure of condensed systems is presented.