About the stability of noble-metal surfaces during VUV-photoemission experiments

We report on a rapid change in high-resolution VUV-photoemission spectra of the Shockley-type surface state on the (1 1 1)-surfaces of Cu, Ag and Au at low temperatures. From a systematic series of experiments and a careful analysis of the spectroscopically observed surface deterioration, we infer that the reason for the changes is an adsorption of activated hydrogen, produced by the used He-discharge lamp. This result is in contrast to the conclusions of an earlier high-resolution photoemission study, in which the aging process was interpreted as a consequence of a VUV-radiation induced structural disorder of the metal surface itself.