2DELTAI-A2III AND 2 2SIGMA+-2III BAND SYSTEMS OF BORON MONOSULFIDE MOLECULE

Emission bands near 5000 and 3100 Å, from a microwave discharge tube containing solid 10B232S3, 11B232S3 or 11B234S3, have been photographed at high resolution. The isotope effects show that the emitter of all bands is the boron monosulfide molecule. Rotational analysis of the strongest band of each region shows that it is the 0-0 band of a system terminating in the A2Πi state characterized earlier by Zeeman. Constants obtained for the new upper states are (cm-1): {A table is presented}. A BS band (at 5100 Å) having no obvious relationship to known band systems is analyzed and found to be the 0-0 band of a 2Σ-2Πi system for which both states are new. The derived constants are (cm-1): {A table is presented} This 2Πi state, like the A2Πi and the 2Δi states, exhibits a spin-orbit doubling, AΛ, of more than 300 cm-1. Extension of Zeeman's analysis of the A2Πi-X2Σ+ bands reveals vibrational and rotational mixing of the A and X-states while extension of his analysis of the C2Πr-X2Σ+ system reveals a crossing of the C2Πr and B2Σ+ potential curves, at v = 1 and 5, respectively. © 1969.