ANGULAR DEPENDENT SOFT-X-RAY ABSORPTION-SPECTROSCOPY OF VANADIUM-OXIDES

We have used angle-dependent soft x-ray absorption spectroscopy to stu dy the nature and orientation of the unoccupied states of V2O5, V6O13, VO2, and V2O3. In the oxygen K edge (vanadium L(III) and L(II)) spect rum of V6O13 and V2O5, pre edge features are apparent; these vary dram atically with the angle between crystal axes and the polarization vect or of the incident synchrotron radiation. The O K- edge (V L- edge) x- ray absorption spectra probe unoccupied states of O 2p (V 3d) symmetry , and the angular dependence thus reveals the spatial orientation and character of these hybridized O 2p - V 3d molecular orbitals in those highly anisotropic materials.