Band structure dependent damping in photoemission from copper

Abstract

A simple model of damping of excited electrons in crystals is investigated, and the consequent broadening of angular resolved photoemission spectra is discussed. For a photon energy of 11.7 eV the exit angle dependence of the peak width of photoelectrons emanating from the sp band of Cu(111) is estimated from lifetime and band structure data and compared with the authors previously published spectra. A predicted sharp linewidth enhancement and maximum for k/sub /// approximately=0.83 pi /a along Gamma M is seen experimentally by a more gradual rise saturating at k/sub /// approximately=0.75 pi /a. Finally, angular tuning is used to obtain electron inverse lifetimes in copper of 2.7+or-0.4 eV and 3.5+or-0.4 eV at energies of 16.6 and 20.7 eV above the Fermi level, respectively.