The Absorption Spectrum of Chlorine Dioxide

The spectrum of the visible and ultraviolet absorption bands of Cl${\mathrm{O}}_2$ has been studied under various dispersions. The band heads were measured with high precision. The result of the vibrational analysis shows that the bands may be represented by $\{\nu =20957.2\mathrm{}+302.9({v_1}^{\prime }+\frac{1}{2})-2.3\mathrm{}{({v_1}^{\prime }+\frac{1}{2})}^2+721.68({v_2}^{\prime }+\frac{1}{2}\left)\right\}\{-2.797\mathrm{}{({v_2}^{\prime }+\frac{1}{2})}^2+271.2({v_3}^{\prime }+\frac{1}{2}\left)\right\}\{-4.42({v_1}^{\prime }+\frac{1}{2}\left)\right({v_2}^{\prime }+\frac{1}{2})-3.9({v_1}^{\prime }+\frac{1}{2}\left)\right({v_3}^{\prime }+\frac{1}{2}\left)\right\}\{-5.9({v_2}^{\prime }+\frac{1}{2}\left)\right({v_3}^{\prime }+\frac{1}{2})-529.0({v_1}^{\prime \prime }+\frac{1}{2}\left)\right\}\{-1104.8({v_2}^{\prime \prime }+\frac{1}{2})-954.4({v_3}^{\prime \prime }+\frac{1}{2})+4.8\mathrm{}{({v_3}^{\prime \prime }+\frac{1}{2})}^2,\}$ yielding three normal frequencies for each upper and lower electronic state. The essential difference between the present analysis and that of the previous investigators is discussed. Rotational lines are partially resolved on the plates taken in the second order with a 21-foot grating. Two fundamental and one combination bands in the region 4-11μ were located with a self-recording spectrometer, and these are compared with the recent observation of Bailey and Cassie. Molecular constants have been calculated from a characteristic determinant given by Yates. They are found to be consistent with the observed isotope effect of chlorine.