Lack of photon energy dependence of the Fermi surface of n=1 Bi2Sr2-xLaxCuO6+δ-single crystals

The accuracy in Fermi surface determination of the most commonly studied HTc- superconductor Bi2Sr2CaCu2O8 in the non-superconducting state depends on a number of parameters. The occurence of shadow and umklapp bands yields replicas of the Fermi surface. Besides sample quality (leading to scattering and therewith broadening) furthermore the magnitude of the bilayer splitting for n=2 compounds is not quantitatively accessible. In the case of Bi2Sr2-xLaxCuO6+delta with only one CuO2 layer per unit cell a number of these parameters can be controlled in a way that the intrinsic linewidth and dispersion can be determined more unequivocally. In this contribution we investigate the Fermi surface of n=1 material at various photon energies by high resolution photoemission.