On theΠu2→Πg2Bands of CO2+. Part IV

In this last part of the work on the ${}_{}{}^2{}_{}{}^{}\Pi _u^{}{}_{}{}^{}\to {}_{}{}^2{}_{}{}^{}\Pi _g^{}{}_{}{}^{}$ bands of the C$\mathrm{O}_2^{}{}_{}{}^{+}$ molecule all data are collected on bands for which no classification could be found or for which the classification suggested is for any reason considered as hypothetical. Bands belonging to two groups around $\lambda 3760$ and $\lambda 3915$ are classified tentatively as transitions ${v_1}^{\prime }=0,1,2,3,4\mathrm{}$; ${v_2}^{\prime }={v_3}^{\prime }=0\mathrm{}\to {v_1}^{\prime \prime }=0,1,2,3\mathrm{}$; ${v_2}^{\prime \prime }={v_3}^{\prime \prime }=1\mathrm{}$. The upper states are probably identical with the vibrational levels of the symmetrical array discussed in the first three parts of this work. The rotational analysis of the bands (8 sub-bands) is given in Tables I and II, the vibrational schemes for the two systems of sub-bands (12 in all) are presented in Tables III and IV. Very weak bands around $\lambda 3245$ and $\lambda 3370$ are classified as transitions ${v_1}^{\prime }=0,1,2\mathrm{}$; ${v_2}^{\prime }=0\mathrm{}$; ${v_3}^{\prime }=1\mathrm{}\to {v_1}^{\prime \prime }=0,1,2\mathrm{}$; ${v_2}^{\prime \prime }=1\mathrm{}$; ${v_3}^{\prime \prime }=0\mathrm{}$. The rotational analysis of the bands (10 sub-bands) is given in Tables V and VI, the vibrational schemes for the two systems of sub-bands are presented in Tables VII and VIII. The tentative classification of these four groups of bands leads to provisional values for the frequencies of the antisymmetric vibration ${\nu }_3$. These values are included in the following table presenting a comparison for the ground state of the molecule C${\mathrm{O}}_2$ with the corresponding frequencies for the ground state ${}_{}{}^2{}_{}{}^{}\Pi _g^{}{}_{}{}^{}$ and the excited state ${}_{}{}^2{}_{}{}^{}\Pi _u^{}{}_{}{}^{}$ of the molecule C$\mathrm{O}_2^{}{}_{}{}^{+}$. The rotational constants in the first approximation for the ground state of the ion are thus: ${B_{v_1{v}_2{v}_3}}^{\prime \prime }={B_{000}}^{\prime \prime }-0.0014\mathrm{}{v_1}^{\prime \prime }-0.0042({v_2}^{\prime \prime }+{v_3}^{\prime \prime })$; ${B_e}^{\prime \prime }=0.3849\mathrm{}$ and 0.3867 for the sub-states ${}_{}{}^2{}_{}{}^{}\Pi _{\frac{3}{2g}}^{}{}_{}{}^{}$ and ${}_{}{}^2{}_{}{}^{}\Pi _{\frac{1}{2}g}^{}{}_{}{}^{}$, respectively. In Table IX the rotational analysis is presented for 8 sub-bands from the region $\lambda 3500-\lambda 3850$. No classification for these bands could be found. In Table X the remainder of observed but not classified weak band edges, groupings of lines and bands of a more complicated structure are listed. Several of them present special features of interest for future investigations.