Theory of angle-resolved photoemission spectroscopy intensities from the CuO2 plane -: art. no. 075107

We present a theory for the photon energy and polarization dependence of angle-resolved photoemission spectroscopy (ARPES) intensities from the CuO2 plane in the framework of strong correlation models. We show that for electric field vector in the CuO2 plane the 'radiation characteristics' of the O 2p(sigma) and Cu 3d(x)(2)-y(2) orbitals are strongly peaked along the CuO2 plane, i.e., most photoelectrons are emitted at grazing angles. This suggests that surface states play an important role in the observed ARPES spectra, consistent with recent data from Sr2CuCl2O2. We show that a combination of surface state dispersion and Fano resonance between surface state and the continuum of low-energy electron-diffraction states may produce a precipitous drop in the observed photoelectron current as a function of in-plane momentum, which may well mimic a Fermi-surface crossing. This effect may explain the simultaneous "observation" of holelike and electronlike Fermi surfaces in Bi2Sr2CaCu2O8+delta at different photon energies. We show that by a suitable choice of photon polarization one can, on the one hand, "focus" the radiation characteristics of the in-plane orbitals toward the detector, and, on the other hand, make the interference between partial waves from different orbitals "more constructive".