Structure of the Third Positive Group of CO Bands

Abstract

THE third positive group of CO bands has been studied often before, but no satisfactory analysis of the bands seems to have resulted from it. Therefore we have photographed the bands in the second and third order of a 21-ft. concave grating with 20,000 lines per inch. So far, we have studied the bands 0.0 to 0.4 with heads at 2833, 2977, 3134, 3305, and 3493 A. The bands are due to a ³σ³II transition. The triplet separation of the ³σ state is unnoticeable for J<20. Under these conditions we must expect 15 branches if the resultant spin is not yet completely coupled to the rotational axis (transition from case a to case b). We found 13 of these branches arid traces of the remaining two, which are too faint to be observed among the strong main branches. The five heads which are characteristic for the bands under low dis-persion are the heads of the 0₃, 0₂, P₃, P₂, and P₁ branches (in the simplified notation of case b). The initial level shows very strong perturbations from about K = 16 on, and slight irregularities also for very small K values. This fact makes an analysis of the higher lines of the bands much more difficult, and we have not yet completed this part entirely. The moment of inertia for the final state is 16.5 × 10^-40, and for the initial state approximately 14.3 × 10^-40. The character of the λ-doubling and the number of missing lines near the origin identifies the final ele-ctronic state as a regular ³II state.