AC Methods for the Determination of Photoelectron Energy Distributions

The sensitivity of the Spicer-Berglund retarding-potential method for the determination of photoelectron energy distributions may be improved by an order of magnitude by a more effective cancellation of the capacitative component of the signal. A double modulation technique, in which energy distributions can be traced from saturated photocurrents of the order of 10−11 A, is also described. This method can be employed to eliminate steady thermionic or photoelectric currents many orders of magnitude greater than that under investigation.