Abstract
The intensity mechanisms in a 2 Π 1 2 - 2 Π 3 2 transition are examined in the context of the X 2 2 Π 1 2 -X 1 2 Π 3 2 transition in TeH observed by Fink et al. [ J. Mol. Spectrosc. 138, 19–28 (1989)]. Such intramultiplet state combinations, though allowed by the magnetic dipole selection rules, are forbidden for the electric dipole mechanism, and yet in TeH the latter choice was made based on the sign of the Λ-doubling parameter q. Our scrutiny of the intensity distribution in the 0-0 band has revealed that branch linestrengths involving a purely vibronic moment are inadequate and need to be supplemented by orbit-rotation corrections. The sizeable Λ-doubling in the X 2 2 Π 1 2 substrate ( p ∼ 2 cm −1) allows satisfactory modelling of the intensities on the basis of mixing with a unique perturber 2Σ + state. The resulting line strength formulas contain the single vibronic moment μ ⊥ and the two rovibronic moments Y and Z. Interestingly, the magnitude and even the sign of Z μ ⊥ determined from the intensity fit provide independent evidence negating the magnetic dipole option.
Published Version
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