Energies of, and Transition Intensities Associated with, the Rotational Levels of Nearly Degenerate A1A2 Pairs of Vibronic States in Molecules of Symmetry C3v

Abstract

Expressions for the energies of the rotational levels associated with a nearly degenerate A₁A₂ pair of vibronic states in a molecule of symmetry C_3v are presented. These expressions take into consideration Coriolis interaction between the levels associated with the A₁ vibronic state and the levels associated with the A₂ vibronic state. Expressions for the intensities of rotational lines in transitions involving such a nearly degenerate A₁A₂ pair of vibronic states are also presented. In certain cases transitions involving a (accidentally) degenerate A₁A₂ pair of vibronic states will have the same appearance as transitions involving a (necessarily) degenerate E vibronic state. A loose analogy between the problem discussed in this paper and the problem of spin uncoupling in a ²Π state of a diatomic molecule is pointed out.