Experimental Investigation of the Self-Broadening Coefficients in the ν1+ ν3Band of SO2and the 2ν2Band of H2S

Abstract

The self-broadening coefficients for 118 lines in the ν1+ ν3band of32SO2, 5 lines in the ν1+ ν3band of34SO2, 10 lines in the ν1+ ν2+ ν3− ν2band of32SO2, and 13 lines in the 2ν2band of H2S were measured in the spectral region between 2464 and 2503 cm−1by applying a tunable diode laser spectrometer. The transitions from the ν1+ ν3band of32SO2cover the quantum number range 2 ≤J″ ≤ 48, 0 ≤Ka″≤ 16 and contain 66 lines from the P-branch, 46 lines from theQ-branch, and 6 lines from theR-branch. The self-broadening coefficients vary between 0.240 cm−1/atm ≤ γSO2–SO2≤ 0.504 cm−1/atm. As with previously studied bands of SO2a pronounced decrease of the broadening coefficients with increasing quantum numberKa″was found. On the other hand, a significant trend onJ″ could not be stated. Altogether, the absolute values of the self-broadening coefficients are comparable. For the self-broadening coefficients from the 2ν2band of H2S with 4 ≤J″ ≤ 13, 1 ≤Ka″≤ 5 a decrease of the broadening coefficient with increasingJ″ is obvious, whereas noKa″-dependence was found even when recently published data for the three fundamental bands were included. This corresponds to the different sizes of the rotational constants of SO2and H2S. For the ν1+ ν3band of SO2, lines from different branches but with identical ground state could be compared. As typical behavior, a trend γR-branch< γQ-branch< γP-branchwas found, as predicted by theoretical values.