A two-dimensional data-acquisition system for a display-type electron energy analyser

A parallel-detection digital data-acquisition system for an ellipsoidal-mirror display-type analyser (EMDA) is described. The operation characteristics for its use in photoelectron spectroscopy are presented. The system is based on an optical readout of the two-dimensional angular intensity distribution of photoelectrons with a phosphor screen of a microchannel plate and a precision SIT video camera. A real-time image-processing system is used for digital video-data processing. Angular distribution patterns of photoelectrons can be obtained in a time of 4-10 s. Energy distribution spectra are recorded in a parallel-detection mode within the whole acceptance cone (88 degrees ) of the EMDA more than two orders of magnitude faster than with a conventional zero-dimensional electrostatic electron energy analyser. The different modes of operation of the EMDA and their realisation with the data-acquisition system are described.