HIGH-RESOLUTION ABSORPTION-SPECTRUM OF CO2 BETWEEN 1750 AND 2000 .1. ROTATIONAL ANALYSIS OF 9 PERPENDICULAR-TYPE BANDS ASSIGNED TO A NEW BENT-LINEAR ELECTRONIC-TRANSITION

The absorption spectrum of CO2 gas between 1750 and 2000 angstrom has been photographed at high resolution and proves to be extremely rich in bands with considerable rotational fine structure. In spite of the great complexity, we have been able to achieve a coherent preliminary analysis of 9 bands defining an excited state bending progression and which are among the stronger bands in this spectral region. The symmetry species obtained for the upper levels is consistent with their assignment to the 1 1A2 state, rendered vibronically allowed by excitation of one quantum of the asymmetric stretching nu(3)'(b2) vibration. The assignments are discussed in relation to recent ab initio calculations. Many perturbations are present in the spectra and some of these have been satisfactorily explained.