DISTORTION OF XAFS SPECTRA RECORDED WITH X-RAY EXCITED OPTICAL LUMINESCENCE

We have measured the XAFS spectra of a thick powdered sample of EuCl2 at the L edges of Eu using the X-Ray excitation of optical luminescenc e (XEOL). The spectra exhibit a strong distortion resulting in an appa rent derivative like shape. We propose an extension of the phenomenolo gical theory developed recently by Emura et al. to include the case of not transparent samples. Whenever the self-absorption is significant, then the shape of the excitation spectra depends on the direction of emission.