The ν1+ ν3and 2ν1+ ν3Band Systems of SO2: Line Positions and Intensities

Abstract

The room temperature infrared spectra of thea-type ν1+ ν3, ν1+ ν2+ ν3− ν2, and 2ν1+ ν3bands of32SO2and the ν1+ ν3band of34SO2have been recorded using a difference-frequency laser spectrometer and completely analyzed. It is possible to reproduce the rotational energy levels for the (201) and (111) vibrational states using a single Watson-type Hamiltonian, but it is necessary to consider the weak Fermi-type interaction coupling the rotational energy levels of the (101) state with those of the (021) vibrational state in order to fit the energy levels of (101). The band centers, ν0(101), ν0(111), and ν0(201), were determined to be 2499.87003(20), 3010.31730(20), and 3629.76194(30) cm−1, respectively, where the uncertainty cited includes an estimate of the uncertainty in the wavenumber calibration. For the34SO2isotopic species, ν0(101) was found to be 2475.82917(57) cm−1. A complete set of rotational and centrifugal distortion constants was obtained for each state. In addition, precise line intensities were determined for each band yielding improved band transition moments. The integrated band intensities at 296 K have been found to beSv(ν1+ ν3) = 0.539(23) × 10−18,Sv(ν1+ ν2+ ν3− ν2) = 0.425(18) × 10−19, andSv(2ν1+ ν3) = 0.607(25) × 10−20cm−1/(molecule cm−2). The total integrated intensity of the ν1+ ν3band system was also determined at 0.11 cm−1resolution from dilute mixtures of SO2in N2at atmospheric pressure. The value ofSv(ν1+ ν3) determined from this technique was 0.537(16) × 10−18cm−1/(molecule cm−2), in excellent agreement with the high resolution method. The uncertainties in parentheses are estimated experimental errors.