Electronic structure of KNbO3: Nb M-4,M-5 x-ray-fluorescence measurements

We present synchrotron based soft x-ray emission (XES) measurements (Nb L b eta(2,15), Nb L gamma(1), Nb M-3, Nb M-4,M-5, O K alpha) and theoretical ca lculations of x-ray emission spectra of KNbO3. The obtained results are com pared with x-ray photoemission spectroscopy valence-band measurements and b and-structure calculations. The Nb M4,5 emission spectra show strong disper sion and by tuning the exciting synchrotron radiation through the Nb 3d thr eshold (E-exc=206.5-240.6 eV), we identify contributions to the valence emi ssion from the decay of both holes, 3d(5/2) and 3d(3/2). It is also shown t hat it is generally possible to measure M-3(4d5s-->3p(3/2)) x-ray emission spectra of 4d metals in order to study the distribution of 4d valence-band states. [S0163-1829(99)03331-7].