Angle-resolved Cu and O photoemission intensities in CuO₂ planes

Using a mapping from the three-band extended Hubbard model for cuprate superconductors into a generalized t-J model, and exact diagonalization of the latter in a 4×4 cluster, we determine the quasiparticle weight for destruction of Cu or O electrons with definite wave vector k. We also derive an approximate but accurate analytical expression which relates the O intensity with the quasiparticle weight in the generalized t-J model. The k dependence of Cu and O intensities is markedly different. In particular the O intensity vanishes for k=(0,0). Our results are relevant for the interpretation of angle-resolved photoemission experiments.