FORBIDDEN TRANSITIONS IN DIATOMIC MOLECULES: III. NEW AND ABSORPTION BANDS OF THE OXYGEN MOLECULE

Abstract

Two new forbidden transitions of the O2 molecule have been found. They give rise to very faint absorption bands overlapping the much stronger forbidden [Formula: see text] bands previously described. The upper states are identified as [Formula: see text] and 3Δu respectively, both of which arise from the same electron configuration as the known states [Formula: see text] and [Formula: see text]. For the [Formula: see text] state the following vibrational and rotational constants have been determined: Te = 36678.91, ωe = 650.49, ωexe = 17.036, ωeye = −0.1056, ωeze = −0.00744, Be = 0.8261, αe = 0.0205, γe = −0.000830 cm.−1, γe = 1.597 × 10−5 cm. The constants are based on the assumption of a certain vibrational numbering which may have to be revised (increased). For the 3Δu state the data are quite fragmentary and only two rotational constants, B5 = 0.8177, B6 = 0.7915, and one vibrational quantum, [Formula: see text], have been determined. The bands of the [Formula: see text] system are very close to those of the [Formula: see text] system and represent in all probability the analogue in free O2 of the diffuse triplet bands of Wulf, Finkelnburg, and Steiner ascribed to O4. The positions of the new [Formula: see text] and 3Δu states agree closely with those predicted by Moffitt. Almost half of the unidentified features of the spectrum of the nightglow agree within 5 Å with the predicted positions of emission bands of the [Formula: see text] system.