Bands of D2 and T2 Originating from the Lowest Excited 1sigma G States (1s) Sigma)(2s Sigma)1sigma G and (2p) Sigma) Squared 1sigma G

Bands of the two extensive band systems (1Sigma g) (2s sigma)1Sigma g to (1Sigma g) (2p sigma)1Sigma g and (2p sigma) squared 1Sigma g to (1Sigma g) (2p sigma)1Sigma u of D2 and T2 are presented. The initial states interact strongly and the result of this interaction is a potential curve with two minima, such as computed by Davidson, with which the observations are compatible. The lower vibrational states can be assigned to the individual minima, the higher ones are clearly above the intervening maximum. The presence of perturbations and the comparison between the isotopes result in a fairly definite assignment of all vibrational quantum numbers, even though the low states belonging to the far minimum have not yet been located empirically.