HIGH-RESOLUTION X-RAY-PHOTOEMISSION STUDY OF SINGLE-CRYSTALLINE SR2CUO2CL2

Sr2CuO2Cl2 contains CuO2 planes separated by ionic SrCl block layers a nd can be regarded as a model substance for cuprates concerning many o f their physical properties, in particular the dynamics of valence-ban d holes in a two-dimensional antiferromagnetic background. We present and discuss core-level and valence-band photoemission data. The Cu-2p photoelectron spectrum differs from the spectra of other cuprate compo unds, in particular with regard to the parent cuprates of the high-T-c superconductors. The Cu-2p main lines are comprised of more than two peaks with strong satellite emission which exhibits a distinct angular -dependent fine structure. We present calculations of a Cu5O16 cluster within the d-p model and discuss the features in the main line of the Cu-2p photoemission spectrum in terms of the different screening chan nels available in CuO2 planes.