Study of the Rotational Structure of the Forbidden ν8 Band of the C2H2D2-CIS Molecule

Abstract

The spectrum of the cis-ethylene-d2 (C₂H₂D₂-cis) molecule is recorded with a Bruker IFS 120 HR Fourier spectrometer in the region of 600–1200 cm^–1 with spectral resolution of 0.0021 cm^–1. As a result of analysis of the experimental spectrum, 36 transitions are first assigned, based on which seven upper energy levels of the state (ν₈ = 1) are determined. The ν₈ band is symmetry-forbidden, and its transitions appear in the IR spectrum only due to the strong c-type Coriolis interaction between the states (ν₈ = 1) and (ν₇ = 1). The parameters describing the rotational structure of the ν₈ band are obtained.