RESONANT X-RAY-EMISSION SPECTRA OF CUO AND LA2CUO4

The 3d --> 2p x-ray emission spectra of CuO and La2CuO4 are measured u nder the selective excitation from the Cu 2p core-level to the Cu 3d l evel. The main peak is observed at about 1.5 eV below the absorption p eak in both materials. The width of the main peak in CuO is somewhat n arrower than that in LazCuO(4). In La2CuO4, a satellite is observed at 3.5 eV below the main peak, while the spectrum of CuO does not show a satellite clearly. The main peaks in both materials are ascribed to t he transition to the 3d(9) excited state and the satellite is attribut ed to the 3d10 (v) under bar-charge-transfer excited state. From the a bove results, it is confirmed that the hybridization between the 3d(9) and 3d(10)(v) under bar states is larger in La2CuO4 than in CuO.