Influence of CO_2-laser linewidth on the measured absorption coefficients of atmospheric water vapor and ammonia

Abstract

We describe the results of analysis of the experimental and calculated data on the water vapor and ammonia absorption coefficients of CO2-laser radiation. We believe that the different halfwidths of CO2-laser lines, caused by different pressures of the working mixtures in specific experiments, are probably the reason for discrepancies between data presented in various papers.

On the Pressure and Temperature Dependence of the Absorption Coefficient of NH3

“…A 0 (σ, T) is the normalized absorption coefficient depending on the temperature and the wave number σ of the line; P NH3 is the NH 3 pressure. Table 2 gives the self-absorption coefficient of the two wings of P P(5, 2) s and P P(7, 4) s lines as a function of the square of NH 3 pressure (P 2 NH3 ) at T = 296 K. Figure 6 shows the variation of self-absorption coefficient of the right wings of P P(5, 2) s and P P (7,4) a lines as a function of the square of NH 3 pressure (P 2 NH3 ). One can see that the wing absorption coefficients increase linearly with pressure.…”

“…NH 3 absorption coefficients were also measured by Allario and Seals [6] using several transitions of a CO 2 laser for small concentrations of NH 3 perturbed by N 2 . The influence of CO 2 Laser line width on the measured absorption coefficients of atmospheric ammonia has been studied by Voitsekhovskaya et al [7].…”

“…International Journal of Spectroscopy Table 2: Self-absorption coefficient of the two wings of P P(5, 2) s and P P (7,4) s lines as a function of the square of NH 3 pressure (P 2 NH3 ) at T = 296 K.…”

“…Results of multipressure fits for the P P(7,3) s line in the ν 4 band of NH 3 self-perturbed at 296 K. (-) and (•) are the measured and calculated values, respectively. Residual (measured minus calculated) spectra are shown in the lower part of the graphs.…”