Two-dimensional toroidal electron analyzer for energy and angular dispersive measurements

A toroidal electrostatic analyzer with a two-dimensional position-sensitive electron detector has been developed for the measurement of differential e xcitation cross sections in electron-ion collisions. The electron position is resolved simultaneously in the energy and angular dispersive directions of the analyzer. The present electron analyzer is specially designed with a narrow curved entrance slit and a wide exit slit coupled with an exit lens system after the toroidal deflector, which can give a wide energy disperse d range of 20% of the mean pass energy and a large angular range extending from 30 degrees to 120 degrees. The performance of the spectrometer has bee n studied by measuring the scattered electrons from Ar atoms and from a hig hly oriented pyrolytic graphite surface, indicating the usefulness of the p resent analyzer in electron spectroscopy. A brief description of the method for a spectrum transformation from Cartesian coordinates to polar coordina tes is also presented. (C) 1999 American Institute of Physics. [S0034-6748( 99)01804-3].