Reexamination of the Electronic Structure of ${{\mathrm{Bi}}_2{\mathrm{Sr}}_2{\mathrm{CaCu}}_{2}O}_{8+\mathit{\delta }}$ and ${{\mathrm{Bi}}_2{\mathrm{Sr}}_2{\mathrm{Cu}}_{1}O}_{6+\mathit{\delta }}$: Electronlike Portions of the Fermi Surface and Depletion of Spectral Weight near $\overline{\mathit{M}}$

We present a reexamination of the electronic structure and Fermi surface (FS) topology of Bi-Sr-Ca-Cu-O (BSCCO) as obtained from angle-resolved photoemission experiments. By applying a stricter set of FS crossing criteria as well as by varying the incident photon energy outside the usual range, we have found very different behavior from that previously observed. In particular, we have found a FS that is centered around the $\Gamma$ point and contains electronlike portions, and we observe a depletion of spectral weight around $\overline{M}$. The flat bands observed at other photon energies may indicate the presence of two electronic components in the cuprates.