Secondary Electron Emission from Diffusion Pump Oils II. δ-η Analysis for DC-705

Abstract

Secondary electron emission (SEE) properties of DC-705 (Trade mark: Dow Corning Chemical Co.), which is a molecular substance, have been studied. Measurements were made on SEE coefficient and on in elastic reflection coefficient for primary energy E _p of 50–2000 eV at various thicknesses of DC-705 on a tungsten substrate. The maximum emission depth of inelastically reflected primaries is given as a function of E _p and is proportional to E _p ⁿ (n=2.1±0.3). The maximum emission depth of true secondary electrons is found to be 20–30 Å and independent of E _p for E _p higher than 400 eV. This value is much smaller than those for other molecular substances found by other workers. The possible causes are discussed. The efficiency of inelastically reflected electrons in producing true secondaries is 3 to 4 times larger than that of direct primaries.