State of bismuth in BaBiO3 and BaBi1−<i>x</i>Pb<i>x</i>O3: Bi 4<i>f</i> photoemission and Bi <i>L</i>3 absorption spectroscopic studies

The 2p 6d feature in the Bi L3 spectra has different energies in the semiconducting (0.0≤x&amp;lt;0.7) and the superconducting (x=0.75) compositions of BaBi1−xPbxO3. The Bi 4f core level spectrum shows distinct features ascribable to Bi III and Bi V in BaBiO3 and in the semiconducting compositions; the width of the 4f peaks is also considerably larger in these compositions compared to that in BaBi0.25Pb0.75O3, which shows a single sharp Bi 4f feature.