FORBIDDEN ROTATIONAL AND ROVIBRATIONAL TRANSITIONS IN H-3+ - 1ST PRINCIPLES CALCULATIONS

Calculations of the linestrengths and transition frequencies of the forbidden pure rotational spectrum of H3+ in the vibrationally excited ν2 state are presented. These transitions occur in the far-infrared region, and their observation may be complicated by ν1 - ν2 difference transitions. Examples of these are also given. Forbidden rovibrational transition frequencies and linestrengths have also been calculated in the frequency range 2000-3000 cm-1. The bands (ν2 + ν1) - ν2 and (2ν2 (l = 0) + ν1) - 2ν2 (l = 2) are found to be particularly strong. Possible phenomenological explanations for the observed line intensities are discussed. Two routes to obtaining the energy levels of the ν1 manifold of H3+ are suggested. © 1990.