COMPARATIVE PHOTOEMISSION-STUDIES OF BI2-XPBXSR2CAN-1CUNO2N+4+Y (N=2,3)

XPS and UVPES studies of Bi2212, BiPb2212 and BiPb2223 have been carri ed out. Shifts in various core levels are observed as we move from Bi2 212 to BiPb2223. Core level shifts indicate that the main oxidation st ates of Bi and Pb are III and IV, respectively, in all the three compo unds. The Pb4f core lines show two components indicating their inequiv alent sites. The mixed occupancy of Ca and Sr is clearly shown in the spectra. The decrease in ionic character from two to three CuO2 layer bismuth cuprates is explained on the basis of satellite to main line i ntensity ratio and the energy separation between the main line and sat ellite of the Cu2p core level. The valence band moves towards the Ferm i level in BiPb2223 as compared to Bi2212. Our results are compared wi th band structure calculations of Bi2212 and we suggest possible reaso ns for the ambiguities of O2s resonant photoemission in Bi2212.