Rovibrational analysis of the ethylene isotopologue 13C2D4 by high-resolution Fourier transform infrared spectroscopy

The Fourier transform infrared (FTIR) spectrum of the unperturbed a-type v(12) band of (C2D4)-C-13 was recorded at an unapodized resolution of 0.0063 cm(-1) between 1000 and 1140 cm(-1) for a rovibrational analysis. By assigning and fitting a total of 2068 infrared transitions using a Watson's A-reduced and S-reduced Hamiltonians in the I-r representation, rovibrational constants for the upper state (v(12) = 1) up to five quartic centrifugal distortion terms were derived for the first time. The root-mean-square (rms) deviation of the fits was 0.00034 cm(-1) both in the A-reduction and S-reduction Hamiltonian. The ground state rovibrational constants of (C2D4)-C-13 in the A-reduced and S-reduced Hamiltonians were also determined for the first time by a fit of 985 combination-differences from the present infrared measurements, with rms deviation of 0.00036 cm(-1). The v(12) band centre of (C2D4)-C-13 was at 1069.970824(17) cm(-1) and at 1069.970799(17) cm(-1) for the A-reduced and S-reduced Hamiltonians respectively. The ground state constants of (C2D4)-C-13 from this experimental work are in close agreement to those derived from theoretical calculations using the B3LYP/cc-pVTZ, MP2/cc-pVTZ, and CSSD(T)/cc-pVTZ levels of theory. (C) 2014 Elsevier Inc. All rights reserved.