INFLUENCE OF SURFACE STRUCTURAL DISORDER ON LINEWIDTHS IN ANGLE-RESOLVED PHOTOEMISSION SPECTRA

By combination of high-resolution photoemission data and linewidth ana lysis of low-energy electron diffraction spots we are able to derive a semiquantitative understanding of how disorder (induced by argon-ion bombardment and subsequent insufficient annealing) broadens photoemiss ion peaks. At the example of surface states on Cu(100) and Cu(111) we demonstrate how the linewidth may be extrapolated to ''perfectly'' ord ered surfaces in favorable cases. We also present experimental evidenc e that disorder-induced broadening is dominated by defect scattering o f the photohole and is inversely proportional to the effective masses. Extrapolated ''intrinsic'' linewidths (full width at half maximum) ar e Gamma(i) less than or equal to(21 +/- 5) meV at <(Gamma)over bar> on Cu(111), Gamma(i) less than or equal to(20 +/- 3) meV at (M) over bar on Cu(111), and Gamma(i) less than or equal to(13 +/- 4) meV at (M) o ver bar on Cu(100).