High Resolution Spectroscopy of 1,2-Difluoroethane in a Molecular Beam: A Case Study of Vibrational Mode-Coupling
Abstract
The high resolution infrared spectrum of 1,2-difluoroethane (DFE) in a molecular beam has been obtained over the 2978-2996 cm-1 spectral region. This region corresponds to the symmetric combination of asymmetric C-H stretches in DFE. Observed rotational fine structure indicates that this C-H stretch is undergoing vibrational mode coupling to a single dark mode. The dark mode is split by approximately 19 cm-1 due to tunneling between the two identical gauche conformers. The mechanism of the coupling is largely anharmonic with a minor component of B/C plane Coriolis coupling. Effects of centrifugal distortion along the molecular A-axis are also observed. Analysis of the fine structure identifies the dark state as being composed of C-C torsion, CCF bend and CH2 rock. Coupling between the C-H stretches and the C-C torsion is of particular interest because DFE has been observed to undergo vibrationally induced isomerization from the gauche to trans conformer upon excitation of the C-H stretch.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 29, 1992
- Accession Number
- ADA251286
Entities
People
- C. C. Miller
- Laura A. Philips
- Steven M. Mork
Organizations
- Cornell University Department of Chemistry and Chemical Biology