Novel charged particle analyzer for momentum determination in the multichanneling mode. II. Physical realization, performance tests, and sample spectra

Abstract

Following a design described in a preceding paper, an energy dispersive analyzer system has been constructed for the simultaneous determination of polar angle (ϑ) distributions of charged particles originating on a solid surface in the range 0 °⩽ϑ⩽90 °. The analyzer is a toroidal prism used in an unusual geometry, followed by a truncated cone lens. The starting polar angle is preserved in the spectrometer and translated into the arrival position on a position sensitive detector based on the charge division method. The dependence on azimuthal emission angles (φ) is obtained by recording energy and polar angle dependent spectra after mechanical variation of the azimuth. Total N(E, φ, ϑ) spectra are accumulated with a minicomputer, using a multichannel analyzer as buffer; the point-by-point subtraction of two spectra, e.g., to extract the spectral changes brought about by adsorption on a surface, is possible. Test procedures to check the performance (preservation of angles; energy and angular resolution; invariance of transmission with angle) are described. The analyzer can be used for electron (LEED, AES, UPS, ELS, INS, etc.) and ion (ISS, ESD) spectroscopies of clean surfaces and adsorption layers; sample spectra for LEED, AES, UPS, and ISS are shown.