The dependence of the total absorptance of the bands of carbon monoxide near 4.7 µ and 2.3 µ, and of methane near 3.3 µ, on the temperature, pressure, and amount of absorbing gas, has been measured. Pure absorbing samples were studied for pressures between 100 mm Hg and 1000 mm Hg, and at temperatures up to 400°C, for a fixed pathlength of 30.6 cm. The nature of and possible reasons for the observed temperature dependence of the total absorptance are discussed.
Dennis F. Vanderwerf and John H. Shaw, "Temperature Dependence of the Total Absorptance of Bands of CO and CH4," Appl. Opt. 4, 209-214 (1965)