Thermally induced defects and the lifetime of electronic surface states

The temperature-dependent linewidth of the Γ surface state on Al(100) was measured. The result cannot be reconciled, not even qualitatively, with the well-known model for describing the influence of electron-phonon coupling on the lifetime broadening on electronic surface states. It is argued that this is due to the presence of thermally excited defects on the surface. Incorporating this possibility into the analysis, the measured temperature dependence is found to be consistent with that expected from an ab initio calculation of the electron-phonon coupling strength. This phenomenon should be quite general and, indeed, a reanalysis of recently published data of Au(111) [S. LaShell et al., Phys. Rev. B 74, 033410 (2006)] resolves an apparent discrepancy between the measured and calculated electron-phonon coupling strengths.