Knowledge Bank

High dispersion absorption spectra of $\mathrm{<mrow\; data-mjx-texclass="ORD">35</mrow>}ClO2$ have been photographed in the region 4800 - 4300 {\AA}, with the $ClO2$ gas held at dry ice temperature. Complete rotational analyses have been performed for the 000-000, 010-000 and 002-000 bands, and partial analyses have been possible for bands of the upper state stretching progression, $v100-000$ where $v1=1-5$. The upper state centrifugal distortion constants and the positions of various vibrational Coriolis perturbations give strong evidence that the vibrational level structure of the upper state antisymmetric stretching vibration $\nu 3\prime$ is anomalous, and that there is a sizeable double minimum in the $Q3\prime$ coordinate. This is in agreement with the conclusion of Coon, Cesani and $Loyd1$, but contrasts with that of Richardson, Redding and $Brand2$. The upper state vibrational levels are all predissociated, and there are interesting variations of the line widths with rotation, vibration and spin state.