Influence of surface structural disorder on linewidths in angle-resolved photoemission spectra

By combination of high-resolution photoemission data and linewidth analysis 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 photoemission peaks. At the example of surface states on Cu(100) and Cu(111) we demonstrate how the linewidth may be extrapolated to ''perfectly'' ordered surfaces in favorable cases. We also present experimental evidence that disorder-induced broadening is dominated by defect scattering of the photohole and is inversely proportional to the effective masses. Extrapolated ''intrinsic'' linewidths (full width at half maximum) are 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) over bar on Cu(100).