Coriolis interaction between the [formula omitted] and [formula omitted] bands of 13C2D4 by high-resolution FTIR spectroscopy

Abstract

The Fourier transform infrared (FTIR) spectrum of 13C2D4 in the 1420–1530 cm−1 region was recorded at an unapodized resolution of 0.0019 cm−1 to analyze its A-type ν7+ν8 band. Rovibrational constants of the v7=v8=1 state up to five quartic terms were derived for the first time from a fit of 1100 assigned infrared transitions using the Watson’s A-reduced Hamiltonian in the Ir representation with an rms deviation of 0.00080 cm−1. Some of the transitions of the ν7+ν8 band were perturbed by the upper energy levels of the ν4+ν8 band by a c-type Coriolis interaction. Rovibrational analysis of the perturbed and unperturbed infrared transitions of the ν7+ν8 band allows for the c-type Coriolis resonance parameter, Z7,8c, for the ν7+ν8 and ν4+ν8 interacting bands to be determined for the first time. The band center and three rotational constants (A, B and C) of the v4=v8=1 state were also derived accurately from the perturbed analysis in this work. The rotational constants of both v7=v8=1 and v4=v8=1 states derived from this work were found to agree within 1.1% to the calculated values using MP2/cc-pVQZ and B3LYP/cc-pVQZ levels of theory. The band centers of ν7+ν8 and ν4+ν8 were determined to be 1473.625489(51) cm−1 and 1488.633(11) cm−1 respectively.