Secondary Electron Emission from Diffusion Pump Oils. I

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Abstract
Secondary electron emission (SEE) properties of Octoil-S, DC-704, and DC-705 have been studied by a pulsed-beam method in the primary range 50–2000 eV. For these three specimens, the maximum values of SEE coefficient σ are 2.8, 2.0, and 2.0, respectively, and the primary electron energies which give the maximum σ are equally 200 eV. The maximum values of inelastic reflection coefficient η are 0.14, 0.17, and 0.17, respectively. The results are compared with those for other molecular substances. SEE from tungsten covered with an evaporated film of Octoil-S, DC-704, and a vacuum grease has also been studied. σ varies markedly for every specimens with increasing thickness of the film. This method can be used for quantitative detection of organic contamination in vacuum systems down to average thickness of several angstroms.