, Volume 188, Issue 4, pp 326-338

Messung der Verweilzeit von He-Atomen an Glasoberflächen

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Abstract

Mean sticking times of helium on a glass surface are determined at very low pressures from nonstationary molecular flow through glass capillaries. The temperature range covered is 13.8 °K to 20.4 °K.

Resulting sticking times are of the order of 10−7 to 10−5 sec. They show a characteristic dependence on temperature and pressure.

These measurements can be interpreted by means of a simple model: He-atoms mostly are bound to the surface with an adsorption energyE of 229 cal/mol≙0.01 eV (±20%). However with a probability of 10−4 the energy is 530 cal/mol≙0.023 eV (±6%). In both cases sticking times τ follow the equation τ=τ0exp(E/RT) where τ0 is about 10−9 to 10−10 sec.

Ich danke meinem verstorbenen Lehrer, Herrn Prof. Dr. R.Jaeckel, für die Anregung zu dieser Arbeit, sowie Herrn Prof. Dr. W.Paul, der die Fortführung der Messungen ermöglicht hat, und der Deutschen Forschungsgemeinschaft für großzügige Unterstützung.