Theoretical modeling and experimental testing of a multimode optical system and energy analyzer for electron spectroscopy

Abstract

An electron-optical system and hemispherical electrostatic energy dispersing element for quantitative electron spectroscopy over a wide range of kinetic energies is described. The electron optics were modeled using several calculational techniques, in order to determine the theoretical conditions under which a fixed linear magnification could be obtained. By designing an optical system with a plane of reflection symmetry, fixed magnification focus was possible over a calculated range of retard ratios from 1/40 to 40/1. The optics can be run in two different modes, one with and one without a retarding field grid to achieve the energy retardation. Comparisons between the predictions made using the various computational methods are reported, as well as experimental verification of the actual performance of the electron optics and energy analyzer. A method is described by which the angular acceptance of the electron optics can be varied by changing the excitation potentials on the lenses. The completed system allows for the simple installation of single-channel, multichannel, and spin-polarization detectors without modification of the analyzer.