Absolute evaporation rates for some polar and nonpolar liquids

A method was developed for providing continuously wiped and, therefore, clean liquid surfaces in vacuo. By means of a mass spectrometer detector, the absolute evaporation flux from such clean surfaces was measured for diethylene glycol, glycerine, dibutyl phthalate, and oleic acid. The molecular flux from equilibrium vapor was also measured by the same detector. The ratio of the former to the latter, the evaporation coefficient, was found in each case to be close to unity and independent of the temperature.