Deformation enhanced photoemission from aluminum

Abstract

Measurement of the photoyield of flexurally fatigued aluminum is reported as a function of photon energy for two different initial microstructures of the material. It was found that for photon energies less than about 9 eV fatigue enhances the photoemission. It was also observed that this “photo-stimulated exoelectron emission” is quite sensitive to the initial microstructure. The enhancement occurs much more rapidly with fatigue for well-annealed Al than for work hardened specimens. The results appear to be consistent with a model, to be presented in Part II which is based on a resonant coupling between the surface electromagnetic modes (plasmons) of the metal and the incident photon. This resonance is made possible by the development of dislocation slip steps on the surface during fatigue. The effect of material condition is shown to be primarily a difference in the kinetics of slip step formation. The effects of ion sputtering to remove oxides and of the angle of incidence of the photons are also reported. Above 9 eV the photoyield was found to be almost insensitive to fatigue, usually decreasing slightly.