The Influence of Foreign Gases on the Intensity of Infrared Absorption

Measurements have been made on the effect of helium, argon, oxygen, nitrogen, ethane, carbon dioxide and hydrogen on the maximum absorption by nitrous oxide in the region of 4.5 mu, by using a spectrometer of low resolving power. Some measurements have also been made with carbon monoxide and ethyl bromide as the absorbing gases. Relative "optical" collision diameters, calculated on the postulate that the mean free paths are equal in gas mixtures having the same relative absorption coefficients, show a linear relationship with the gas-kinetic diameters as determined by viscosity measurements. The applicability of Beer's law is discussed in connection with the use of infrared absorption measurements as a means of analysis.