Linearly polarized CuL3-edge x-ray-absorption near-edge structure ofBi2CaSr2Cu2O8

The linearly polarized Cu {ital L}{sub 3}-edge x-ray-absorption near-edge structure (XANES) of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} has been measured and the spectra are interpreted by the full multiple-scattering approach in real space. The polarized spectra over a range of 20 eV can be predicted in terms of the one-electron dipole ({Delta}{ital l}=+1) transition Cu 2{ital p}{r arrow}{epsilon}{ital d}, probing the unoccupied {ital d}-like ({ital l}=2) density of states projected on the Cu site with orbital angular momentum {ital m}{sub {ital l}}=0, 1 in the {bold E}( ){ital z} spectra, and the {ital m}{sub {ital l}}=2, 1, and 0 in the {bold E}{perpendicular}{ital c} spectra. The oscillator strength for the dipole allowed transitions ({Delta}{ital l}={minus}1) Cu 2{ital p}{r arrow}{var epsilon}{ital s} is shown to be a factor of 100 weaker than the 2{ital p}{r arrow}3{ital d} transitions. The Coulomb interaction in the final state between the Cu 2{ital p} core hole and the excited Cu 3{ital d} electron is found to be 5.5 eV forming a bound state below the continuum threshold, the well-known Cu {ital L}{sub 3} white line. On the contrary, the core hole induces a nearly rigid redshift about 1 eV of the high-energy conduction bands.