Electronic structure of MgB2:: X-ray emission and absorption studies -: art. no. 134509

Measurements of x-ray emission and absorption spectra of the constituents of MgB2 are presented. The results obtained are in good agreement with calculated x-ray spectra, with dipole matrix elements taken into account. The comparison of x-ray emission spectra of graphite, AlB2, and MgB2 in the binding energy scale supports the idea of charge transfer from sigma to pi bands, which creates holes at the top of the bonding sigma bands and drives the high-T-c superconductivity in MgB2.