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Updated: Sep 11, 2025

ARL Spectral Fitting as an Application to Augment Spectral Data via Franck-Condon Lineshape Analysis and Color Analysis
Published on: August 19, 2021
Low temperature jet spectra of (DFE)2, DFE-He, DFE-He2 and DFE in the 2210-3105 cm-1 region (DFE = 1,1
A J Barclay1, A R W McKellar2, A Pietropolli Charmet3
1Department of Physics and Astronomy, University of Calgary, 2500 University Drive North West, Calgary, Alberta T2N 1N4, Canada. nmoazzen@ucalgary.ca.
Abstract:
A pulsed supersonic slit jet expansion of a dilute mixture of 1,1 difluoroethylene (DFE) in helium is probed using a tunable infrared source to obtain spectra of (DFE)2, DFE-He, and DFE-He2. The DFE dimer is found to have a slipped antiparallel structure with two-fold rotational symmetry and little or no dipole moment (explaining why no pure rotational spectrum has been observed). An experimental value of 3.44 Å is determined for the separation of the monomer centers of mass. The spectra of DFE-He show line splittings due to tunneling of the He atom from one side of the DFE plane to the other. Rotational analysis of the DFE-He tunneling components in terms of a conventional asymmetric rotor yields small systematic errors due to the presence of large amplitude motions. A relatively weak spectrum is analyzed for one band of DFE-He2, whose structure places the two He atoms in equivalent positions on each side of DFE, very close the location of He in DFE-He. Extensive spectra of DFE monomer are also obtained while searching for the cluster bands. A total of 23 bands from 2210 to 3105 cm-1 are observed. These are the first such high resolution results in this region, and they are of special interest because DFE has been a prototype for the study of vibrational anharmonicity and resonances.
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