The Energy Distribution of Photoelectrons from Sodium

Abstract

The total energy distribution functions for photoelectrons emitted from evaporated sodium surfaces have been determined over a wide range of frequencies, by the use of the retarding potential method with concentric spherical electrodes. Theoretical energy distribution curves have been computed assuming an image field at the surface and following the general theory of Mitchell. It is shown that the theory does not fully account for the experimental results. The discrepancy can be accounted for by assuming a selectively transmitting surface field with a transmission maximum at 0.5 electron volts. The spectral distribution function for the image field has also been computed and compared with the experimental data. Again the agreement is not satisfactory and is only partly corrected by the use of the selective transmission barrier. It is concluded that the frequency dependence of the quantum absorption probability and the energy dependence of the barrier transmission probability differ from the image field predictions. This discrepancy is probably not caused by lack of refinements in the theory, but by the practical impossibility of producing an "ideal" surface of Na.