Rapid deterioration of metallic surfaces induced by intense ultraviolet radiation

We report rapid deterioration of metallic surfaces on irradiation with ultraviolet light. Very fast degradation of the Shockley state of Cu(111) is observed during photoemission at low temperature. A different evolution of the Shockley states during annealing and cooling was also discovered. These observations seem to favor a mechanism based on photon-stimulated chemisorption of hydrogen on the surface. We suggest that this mechanism affects all experiments involving intense radiation and might become a major obstruction for future experiments with microfocused beams.