Line shape in the wing beyond the band head of the 4·3 μ band of CO2

Abstract Quantitative absorpance measurements have been made in pure CO 2 and mixtures of CO 2 with N 2 and O 2 in a 10 m White Perkin-Elmer cell. With absorbing paths up to 50 m-atm, results have been obtained from the band head at 2397 cm -1 to 2575 cm -1 . The continuous absorption, which is due to the extreme tails of the strong lines in the v 3 band centered at 2349 cm -1 , is much less than calculated with the Lorentz line shape. A good fit with the data is obtained with an empirical line-shape which retains the Lorentz pressure dependence but requires a nearly exponential modification of the frequency dependence.