High-resolution measurements made-on the 200–000 telluric band of N2O at 3.9 µ yielded integrated absorption coefficients for individual band lines. When these measurements are combined with laboratory-calibration spectral measurements, 2.0±0.3 mm path N.T.P. is obtained for the amount of N2O present in a standard earth’s air mass.
D. H. RANK, A. F. SLOMBA, E. F. GARDNER, and T. A. WIGGINS, "Abundance of N2O in the Atmosphere," J. Opt. Soc. Am. 52, 858-858 (1962)