Simultaneous Determination of f Values and Vapor Pressures from Optical Absorption Measurements

A method for determining both the f value of an absorption line and the vapor pressure of the absorbing atoms exclusively from optical absorption measurements is defined and discussed. The method depends on making absorption measurements in two regions. The first is at low optical densities, where absorption is linearly proportional to optical density. The second is at higher densities, where the center of the line is fully absorbed and the absorption is proportional to the square root of the optical density. A method for extrapolating measurements from one region to the other is also required. This is accomplished by maintaining a pure liquid in equilibrium with the absorbing vapor species over a temperature range. The method takes into account the effects of collision broadening. Measurements were made on the 3067-Å bismuth line.