Analysis of the 4050-Å Group of the C_{3} Molecule.

The 4050-A group of cometary spectra has been obtained in absorption and fluorescence in the flash photolysis of diazomethane mixed with a large excess of inert gas Spectra taken under high resolution have been measured and analyzed. The electronic transition is shown to be g+ From the rotational analysis of some of the weaker bands, it is established that in the lower (ground) state of the C3 molecule the bending frequency P3 is very small ( 63 cm-'). in the excited state, in which the bending frequency is much larger, there is a strong Renner-Teller (vibronic) interaction which leads to a large splitting of bands with 13 0. Since, in addition in the lower state, on account of the smallness of P3 ' levels with $ 0 are strongly excited at room temperature, a rather complicated vibrational structure of the spectrum arises. in the lower state i-type doubling is large in all vibrational levels with 1 = 1. indeed, the large magnitude of this doubling confirms the low value of P3' An interesting uncoupling effect connected with 1-type doubling is observed for the 12 = 2, 3, and 4 levels of the ground state The study of the Renner-Teller splittings of the excited electronic state ( H) yields for the bending frequency co' = 307.9 and for the Renner parameter E = 0.537. Other rotational and vibrational constants of upper and lower states are listed in Table 5.