X-ray spectroscopic study of Re<SUB>3</SUB>W and Re<SUB>3</SUB>Mo systems

The oxtondcd X-ray absorption fine structure (EXAFS) in the vicinity of the Re Lni absorption discontinuity is recorded in the systems Re3W and Re3Mo and analysed using Levy's theory as well as the graphical method given by Lytle, Sayers, and Stern in order to obtain the average neighbour distance of the rhenium atoms (bond lengths). The chemical shifts of the Re LIII absorption discontinuity in the two systems with respect to the position of the Lm discontinuity in the pure metal is also studied. The somewhat larger chemical sliift observed in the case of Re2W as compared to that in Re3Mo, which reflects greater ionicity in the former system, is consistent with the smaller bond length in the compound