X-RAY EXCITED OPTICAL LUMINESCENCE (XEOL) DETECTION OF X-RAY-ABSORPTION FINE-STRUCTURE (XAFS)

The x-ray excited optical luminescence (XEOL) from a variety of rare-e arth ions was used as a detection mode for the collection of L-edge x- ray absorption fine-structure (XAFS) data. In order to understand the source of the observed optical signal, advantage is taken of the known luminescent response of f ions in a variety of transparent host mater ials. Whereas some samples exhibit an optical response that is indisti nguishable from the transmission XAFS data, other samples show marked differences between I:he data obtained with the two different detectio n schemes. The unexpected optical luminescence of a Gd2O3 Sample is tr aced to a Eu impurity. An optical spectrum of 0.4% Tb in Gd2O2S, excit ed by x-ray photons at the Gd edge, is used to demonstrate that the op tical signal may arise from an ion different from the absorbing ion. T he implications of this energy transfer are discussed in terms of the suitability of XEOL as a detection scheme for XAFS spectroscopy. (C) 1 998 American Institute of Physics. [S0021-9606(98)70540-9].