Abstract
We report resonant inelastic x-ray measurements of insulating La{sub 2}CuO {sub 4} and Sr{sub 2}CuO {sub 2}Cl{sub 2} taken with the incident energy tuned near the Cu K absorption edge. We show that the spectra are well described in a shakeup picture in third-order perturbation theory which exhibits both incoming and outgoing resonances and demonstrate how to extract a spectral function from the raw data. We conclude by showing {bold q} -dependent measurements of the charge transfer gap. {copyright} {ital 1999} {ital The American Physical Society }