Collisional Broadening of CO Absorption Lines by Foreign Gases*

Abstract

Foreign-gas broadening coefficients F, which give the ratio of the line-broadening ability of various gases relative to that of nitrogen, have been determined for 26 rotational lines in the fundamental band of carbon monoxide. The gases studied include H2, D2, He, Ne, Ar, Kr, Xe, CO2, NH3, CH4. For monatomic and diatomic gases with molecular masses less than that of N2, the F values for lines in the band wings are greater than for lines near the band center; the reverse is the case for monatomic gases with molecular masses greater than that of N2 and for CO2. The F values for NH3 and CH4 showed little variation for lines in different parts of the band. The results for the monatomic and diatomic gases are in excellent agreement with Chai’s recent independent measurements of the self broadening of carbon monoxide. The results of the present study have been used in combination with those of Chai and those of Hunt, Toth, and Plyler to obtain values of cross sections of foreign gases for collision broadening of the carbon monoxide absorption lines.