In order to understand the nature of chain-driven superconductivity in Pr2Ba4Cu7O15-δ (Pr247), we have studied the electronic structure of as-sintered non-superconducting Pr247 and annealed superconducting Pr247 samples using photoemission spectroscopy. The O 1s, Ba 3d, Pr 4d, and Cu 2p core-level energy shifts by annealing indicate that electrons doped by the annealing mainly fill the localized Fehrenbacher-Rice (FR) state. The photoemission spectra ρ(ω) near the Fermi level (EF) are derived from the metallic Cu-O double chain and can be fitted to the power-law function plus step function Aω α + Bθ(ω). ρ(ω) near EF is indistinguishable between the as-sintered and annealed Pr247 and the exponent α is ∼1.5. These results indicate that the Cu-O double chain provides the spectral weight near EF and that the annealing affects the localized FR state instead of the near-EF state.
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