Photoemission Measurement of Fermi Surface, Band Dispersion and Quasiparticle Lifetime in YBa2Cu3O6.9

High resolution (20 meV) angle-resolved photoemission measurements on single-crystals of YBa2Cu3O6.9 were analyzed to obtain band dispersion and quasiparticle lifetimes. The mass enhancement is 1.2 for a Cu-O plane band mass and 1.0 for the pdπ chain band. Fitting measured energy distribution curves to a model spectrum that includes self-energy corrections, we find that the imaginary part of the self-energy varies quadratically in the immediate vicinity of EF, and becomes linear above ~20 meV.