Vectorial selective surface effects in the optical absorption and photoelectric emission of thin metal films

The “surface effect” is expected to become observable in the photoelectric emission, and even more early in the optical absorption of very thin metal films. It corresponds to a modified Drude absorption where the electron mean free path is of the order of magnitude of the film thickness. But there is a strong “vector effect” in films with perfectly plane surfaces. The quantum mechanical calculation yields the same result as the modified classical Drude theory, with the additional prediction of a film‐thickness dependent absorption‐threshold. Other related surface effects are briefly discussed, and it is suggested that the excitation of surface plasmons may also lead to a “vectorial, selective photoelectric emission”.