Instrumentation and experimental techniques employed for the determination of the total absorptance ∫A(ν)dν of the bands of various atmospheric gases are described. The total absorptances of the 2563, 2461, 2224, 1285, 1167, 692, and 589 cm−1 bands of pure N2O and N2O mixed with N2 have been determined as a function of absorber concentration w and equivalent pressure Pe which involves the partial pressures of the two gases. The results are given in graphical form. In general, it is found that in situations in which existing theory predicts absorptance proportional to the square roots of pressure and absorber concentration, the total absorptance is indeed nearly proportional to the square root of absorber concentration but not to the square root of the pressure; for the 2224 cm−1 band, ∫A(ν)dν ∝ Pe0.37. In addition to graphical presentation of results, it is possible to express ∫A(ν)dν in terms of w and Pe by means of empirical equations applicable to certain definite ranges of the variables; the validity and the limitations of such empirical equations are discussed. For samples for which the product of the absorption coefficient k(ν) and the absorber concentration is much less than unity for all frequencies in an absorption band, it is possible to measure the band intensity or band strength ∫k(ν)dν. Values of band intensity for the 2563, 2461, 2224, 1167, and 589 cm−1 N2O bands are listed and compared with values previously reported by others.
© 1962 Optical Society of America
Original Manuscript: December 6, 1961
Published: July 1, 1962
Darrell E. Burch and Dudley Williams, "Total Absorptance by Nitrous Oxide Bands in the Infrared," Appl. Opt. 1, 473-482 (1962)