Re-analysis of the high-resolution FTIR spectrum of the [formula omitted] band of 13C2HD3 in the 810–1010 cm−1 region: Coriolis interactions with the [formula omitted] and [formula omitted] bands

Abstract

The spectrum of the C-type ν8 band of 13C2HD3, in the region of 810 to 1010 cm−1, was recorded using a Fourier transform infrared (FTIR) spectrometer, at an unapodized resolution of 0.0019 cm−1. Improved rovibrational constants of the v8=1 state up to five quartic terms were derived from a fit of 1433 assigned unperturbed infrared transitions using Watson's A-reduced Hamiltonian in the Ir representation. For the first time, Coriolis interactions between the v8=1, v6=1 and v3=1 states were studied. A total of 828 perturbed infrared absorption lines, together with the unperturbed infrared transitions, were fitted to obtain a precise set of three rotational constants for the v6=1 state, band centers for the ν6 and ν3 bands, and two a- and b-Coriolis resonance parameters. The fit of an expanded set of ground state combination-differences derived from a larger number of perturbed and unperturbed infrared measurements in this work also yielded rotational and quartic centrifugal distortion constants of the ground state of 13C2HD3 with improved precision, with an rms deviation of 0.00040 cm−1. The experimentally-derived rotational constants of the ground and v8=1 states compared favourably with those from anharmonic calculations using the MP2/cc-pVQZ and B3LYP/cc-pVQZ levels of theory.