Absorption profiles of HCl for the J = 1–0 rotational transition: Foreign-gas effects measured for N 2, O 2, and Ar

Abstract

Line profiles of the J = 1–0 transition of the hydrogen chloride, H 35Cl and H 37Cl isotopomers, were measured with a BWO-based submillimeter-wave spectrometer at AIST in real form: three hyperfine transitions for each isotopomer, i.e., total six lines at 625 and 626 GHz. The effect of foreign gases on the broadening and shift was determined for N 2, O 2, and Ar. The modified Voigt function was applied as the line shape function for preliminary analysis, where the collisional-narrowing effect was clearly observed. In the final analysis, we applied the Galatry function and determined the integral intensity, line center position, Lorentzian width, and contraction parameter for each absorption line. The magnitudes of the foreign-gas pressure-broadening coefficients decrease in order of N 2, O 2, and Ar. The line-shift coefficients were clearly observed, the magnitudes of which decrease in order of Ar, O 2, and N 2. The pressure dependence of contraction parameter was determined, although with poor precision.