A method and apparatus for plotting automatically the secondary electron emission yield curves from metals in an ultra-high vacuum environment are described. The yield curves from metals can be plotted in times of only a few seconds before the surfaces become contaminated. In addition, both the variation of the back-scattering coefficient with primary energy and the yield with angle of incidence of primaries may be plotted. Typical curves from Ni, Pt and Ta are presented to indicate the performance of the apparatus. Measurements using the apparatus are reported on the secondary electron emission characteristics of the three carbides TaC, TiC and ZrC as a function of primary energy and angle of incidence. In addition the yield curves are correlated with a theoretical universal yield curve.
The range of electrons as a function of primary energy below 2 keV, the escape depth of slow secondaries and the efficiency of back-scattered electrons in the production of slow secondaries have been determined in thin aluminium layers deposited on platinum, gold and silver substrates, using an automatic yield measuring device which enables the measurements to be made from contamination-free surfaces.
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