The linearly polarized Cu K-edge x-ray-absorption near-edge structure (XANES) of Bi~Sr2CaCu20g+g (Bi 2:2:1:2)has been measured, and the spectra are interpreted by the multiple-scattering approach in real space. The polarized spectra can be predicted in terms of a one-electron dipole (hl =+1)transition Cu 1s~ep, probing the unoccupied p-like (l = 1) density of states projected on the Cu site with orbital angular momentum m, =O in the E~~z spectra, and the m&=1 in the Etc spectra. Therefore we show that the electronic structure of the high-energy conduction bands, beyond the Cu 3d band, are well described in terms of the one-electron approximation. Final-state eItects induced by the core hole have been studied and calculated. A satellite 7 eV above the main K-XANES peak in both polarizations is shown to be a multielectron shake-up excitation, and it is enhanced going into the insulating phase. Structural information on the copper site in Bi2Sr2CaCu208+z and in Bi2Sr2YCu208+z has been extracted from XANES spectra, providing evidence for the decrease of the Cu-0 distance in the metallic phase.

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