X-ray absorption near edge structures of intermediate valence TmSe single crystals

L₃ and L₁ X-ray absorption spectra of single crystals of TmSe and Tm metal were measured at the synchrotron radiation facility PULS using the Frascati storage ring Adone. Valence fluctuations in TmSe appear from the analysis of the X-ray absorption near edge structures (XANES). The XANES of TmSe shows two well resolved 'giant resonances' at the L₃ threshold due to 2p to 5, epsilon d* transitions localised on the Tm³⁺ and Tm²⁺ ions. The joint analysis of the L₁ and L₃ edges gives information on the symmetry of the conduction states near the Fermi level. The effects of the core-hole-induced relaxation on the measured intermediate valence are not important in Tm compounds. The values of the intermediate valence of Tm in TmSe can be extracted from XANES in contrast to what seems to be the case for Ce in intermediate valence Ce compounds.