Potentialities and Limitations of the XEOL-XAFS Technique

XEOL spectroscopy offers an alternative method to study the local electronic and spatial structures of luminescent materials. This is because XAFS signal can be extracted from the XEOL excitation spectra recorded in the vicinity of X-ray absorption edges. Possible site-selectivity and high quantum yield are the main attractions of this technique. XEOL excitation spectra are however influenced by a variety of different factors which can often result in a dramatic reduction of the XAFS signatures. We have analysed the consequences of different energy transfer mechanisms (diffusion of secondary electronic excitations, non-linearity of the luminescence quantum yield and self absorption of the optical emission) on the shape of the XEOL-XAFS spectra. Experimental data presented in this paper confirm the validity of our analysis which illustrates as well the importance of combinine time-resolved XEOL and XEOL-EXAFS studies