The surface photoelectric current from a pure metal surface is calculated when the frequency of the incident radiation is less than the threshold frequency but greater than one-half the threshold frequency. To do this, second-order stationary perturbation theory is used. The current thus found is normally small. However at great intensities, such as those produced by optical masers, the current might be measurable.

• Received 2 March 1962

DOI:https://doi.org/10.1103/PhysRev.128.2225