The Measurement of Mean Sojourn Time of Molecules in Practical Vacuum Systems

Abstract

A new measurement method of the mean sojourn time of molecules on the surfaces of practical vacuum systems was tested. In a vacuum system, if an adsorbed phase is equilibrated with a gas phase, mean sojourn time can be obtained from measured time constant of evacuation and geometrical time constant (V/S) of the vacuum system.
Mean sojourn time of C₄H₉OH, H₂O and C₂H₅OH was measured on the aluminum (6063-T1) vacuum chamber. The adsorption energy of these gases, estimated from measured mean sojourn time and to τ₀=10^-13 sec, are a little larger than the vaporization energy of them.