Variable angle photoelectron spectrometer *

The design, construction, and performance of a spectrometer for measuring the angular and energy distributions of electrons photoejected by rare gas resonance light is described. Results using 584.4-A photons from a helium lamp are reported. Flexibility of instrumental design allows for the use of other light sources. A 180° hemispherical electrostatic electron energy analyzer is rotatable about the center of an enclosed sample chamber. The instrument is highly automated, with an on-line computer used to control the detector angle and the data acquisition and reduction. This automation is required by the long and continuous data acquisition.