Rotational analysis of the ν6, ν8, ν3 + ν4 interacting infrared system of C2D6 between 960 cm-1 and 1180 cm-1

Abstract

The Fourier transform infrared spectrum of C2D6 (FWHM ≈ 0⋅0030 cm-1) has been investigated in the region of the ν6(A2u) and ν8(Eu) fundamentals, from 960 cm-1 to 1180 cm-1. A strong x, y Coriolis interaction between ν6 and ν8, with K level crossing, generates large displacements of the rotational components of both vibrational states, tuning them to additional local resonances in several spectral regions. Beyond l resonances with Δl = ±2, Δk = ∓ 1 within ν8, a z Coriolis-type resonance of ν8 + ν4 (A1u) and ν6 occurs at K⩽6, and an x, y Coriolis-type resonance of ν8 (- l, K-1) and ν3 + ν4 (K) occurs at K = 7 and 8. A further coupling of ν8 (+ l,K - 2) and ν3 + ν4 (K) has been observed as well. The vibration-rotation constants of ν6, ν8 and ν3 + ν4, and several interaction parameters, have been determined by the least-squares fit of the available data, with an overall standard deviation σ = 4. x 6 10-4cm-1 in the fit of 1661 observed transition waveνmbers. A torsional splitting is observed only in the level...