Knowledge Bank

The weak overtone bands, 2$v3$ and 3$v3$, of $\mathrm{<mrow\; data-mjx-texclass="ORD">32</mrow>}SO2$ have been studied under high resolution and completely assigned. Both bands have been fit using a Watson Hamiltonian. The $3v3$ band, important for the interpretation of the spectrum of the atmosphere of Venus, is essentially unperturbed although a few of the higher-order centrifugal distortion constant are anomalous. In order to fit the 2$v3$ levels to within experimental accuracy ($\pm$$0.0008cm-1$), it is necessary to include a weak Fermi resonance with the nearby lying $v1$+3$v2$ state. The intensities of both bands have also been very satisfactorily fit although the 2$v3$ band exhibits a striking Herman-Wallis effect. The integrated band intensities obtained for $2v3$ and $3v3$ are $Sv$ ($T=296)=0.0995(20)$ and $0.0384(15)cm-2atm-1$ respectively. A complete set of harmonic frequencies and first-order anharmonic constants has been obtained. The effects of Darling-Dennison resonance are surprisingly weak.