Matrix element effects on the Fermi surface mapping by angle resolved photoemission from Bi2Sr2CaCU2O8+x superconductors

We report angle resolved photoemission spectra (ARPES) from the Fermi energy (E-F) over a large area of the reciprocal space using polarized and unpolarized synchrotron radiation light, in two particular distinctive geometries of detection from a mono-domain single crystal of Bi2Sr2CaCu2O8+x (Bi-2212) optimally doped. The data display a wide-ranging level of accord with previously reported ARPES results and clarify how many apparently dissimilar Fermi surface (FS) maps emerge in ARPES, under different experimental conditions. The energy and polarization dependences of the ARPES matrix elements help disentangle primary contributions from the main FS bands to the spectrum from those arising from secondary effects. The remarkable influence of the matrix elements on the ARPES intensity allows us to unravel the principal FS bands, from those robust features associated to the incommensurate superstructure modulations, as well as provide us a reliable route for separating closely placed FS sheets in low dimensional materials. (C) 2003 Elsevier Science B.V. All rights reserved.