A flood-gun arrangement is shown to be useful in alleviating the sample-charging problem in x-ray photoelectron spectroscopy. Modest currents (<10−8 A) of low-energy electrons result in the shifting of photoelectron energy peaks to the proper positions and the reduction of the peak widths.

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The resolution and sensitivity of the spherical-grid retarding potential difference electron-energy spectrometer are discussed. The resolution is shown to be determined by lens effects at the second grid and to be proportional to the ratio of the grid separation to the grid mesh hole size. The resolution of three experimental systems is discussed and shown to be in agreement with the results of computer analysis. The ultimate sensitivity or signal-to-noise ratio developed by the analyzer is shown to be improved by the addition of a ``postmonochromator'' collector scheme which selectively gathers those electrons which pass through the retarding field with a minimum of kinetic energy. Application of the analyzer to Auger electron spectroscopy and x-ray photoelectron spectroscopy is demonstrated. The retarding potential/postmonochromator combination is shown to possess distinct advantages in terms of simplicity and/or sensitivity for both techniques.

Cesium adsorption on vacuum-cleaved p-GaAs (110) was monitored at 10−10 Torr concurrently by photoemission and x-ray photoelectron spectroscopy (ESCA). Cesium was supplied at R = 6.9×1012 atoms/cm2 sec by a calibrated valved room-temperature Knudsen effusion cell. ESCA results showed that the first monolayer of Cs contains N = 6.2×1014 atoms/cm2, that it adsorbs irreversibly, and that fractional coverage is θ = 1−exp(− Rt/N). Maximum photoyield (hence minimum work function) corresponds to θ = 1. The second layer of Cs decreases photoyield, but is desorbed with a time constant of less than 1 min.

A new type of retarding potential difference electron spectrometer using spherical grids is described. The unique feature of the analyzer is a post monochromator section which selectively collects electrons passing the retarding grids with minimum kinetic energy. Factors affecting the resolution of the analyzer are discussed and a comparison with several other spectrometers operating in the resolution range of 0.05% is presented. An application to x-ray photoelectron spectroscopy is presented.