Reexamination of the electronic structure of Bi2Sr2CaCu2O8+delta and Bi2Sr2Cu1O6+delta: Electronlike portions of the Fermi surface and depletion of spectral weight near (M)over-bar

We present a reexamination of the electronic structure and Fermi surface (F S) topology of Bi-Sr-CaCu-O (BSCCO) as obtained from angle-resolved photoem ission experiments. By applying a stricter set of FS crossing criteria as w ell as by varying the incident photon energy outside the usual range, we ha ve found very different behavior from that previously observed. In particul ar, we have found a FS that is centered around the Gamma point and contains electronlike portions, and we observe a depletion of spectral weight aroun d (M) over bar. The flat bands observed at other photon energies may indica te the presence of two electronic components in the cuprates.