OPTOGALVANIC SPECTRUM OF THE CO L'1-PI-B1-SIGMA+(NU-0) BAND AND ELECTRONIC-STRUCTURE OF THE L'1-PI STATE

The rotationally resolved absorption band of CO observed by optogalvanic spectroscopy between 16200 and 16300 cm-1 was identified as the Q branch of the L'-B 1-SIGMA+ (nu' unspecified-nu" = 0) band. The molecular constants of the L' (nu) level were determined as T0 = 103211.81 +/- 0.44 cm-1, B-nu = 1.7535 +/- 0.0048 cm-1, and D-nu = (10.0 +/- 9.5) X 10(-6) cm-1, from which the effective bond length of 0.1184 +/- 0.0002 nm has been derived. An ab initio SCF CI calculation was carried out to determine the character of the L' state. The observed features of the L'-B 1-SIGMA+ and L'-X 1-SIGMA+ (nu-0) bands, as well as the calculation, suggest that the L' state is the mixed state of 1-PI symmetry consisting of configurations of the valence type (...)4-sigma-1-pi-4(5)sigma-(2)2pi and Rydberg types.