Nitric acid vapor line parameters measured by CO laser transmittance

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Abstract
Transmittance curves on pure nitric acid vapor have been determined at CO laser frequencies of 1661.8833 cm−1, 1693.9957 cm−1, and 1711.6199 cm−1. Voigt profile analyses for the first and third frequencies give, respectively, α = (2.02 ± 0.72) × 10−4 Torr−1 cm−1, Δ = (1.63 ± 0.33) × 10−3 cm−1, E(ν0) = (0.668 ± 0.302) × 10−2 Torr−1 cm−1; α = (8.95 ± 0.27) × 10−4 Torr−1 cm−1, Δ = (1.64 ± 0.33) × 10−3 cm−1, E(ν0) = 0.327 ± 0.140 Torr−1 cm−1. Here α is the broadening parameter, Δ the frequency offset, and E(ν0) the extinction coefficient at line center in the Doppler region. Application of the Galatry profile gives the same results as well as a self-diffusion coefficient consistent with the value 0.057 cm2/sec from kinetic theory. Finally, the foreign gas broadening parameter with respect to nitrogen is determined as B = 0.997 ± 0.245 at 1661.8833 cm−1 and B = 5.91 ± 0.78 at 1711.6199 cm−1.