The transmission of infrared radiation from flames through various pathlengths of CO2 was determined in the laboratory. The results show that a considerable amount of flame energy is transmitted in the regions 2.5 µ to 3.5 µ and 4.0 µ to 5.5 µ. For example, a cell length of 1500 cm of CO2 at 760-mm pressure, equivalent to the CO2 content in 50,000 m of atmosphere at sea level, transmitted 20% of the energy in the band region from 4.0 µ to 5.5 µ. Integrated transmittances for the bands at various pressures and cell lengths are presented in tabular form.
J. A. Curcio and D. V. Estes Buttrey, "Transmission of Infrared Radiation from Flames by CO2," Appl. Opt. 5, 231-233 (1966)