THE PERPENDICULAR C-H STRETCHING BAND $\nu_{a}/\nu_{13}$ AND THE TORSIONAL POTENTIAL OF DIMETHYLACETYLENE
Loading...
Date
1996
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
The perpendicular band of the fourfold degenerate C-H stretching vibration of dimethylacetylene ( 2-butyne ) has been measured in the region $2955 - 3065 cm^{-1}$ with Doppler-limited resolution at $\sim$195 K on a diffrenece-frequency laser spectrometer, and on a high resolution Fourier transform instrument at $\sim$295 K s well as in a molecular jet at $\sim$20 K. Over 700 P- and R-branch lines from 37 diffrenet subbands of this band, plus 25 additional unresolved Q-branches were assigned and fitted to the model of rotational-torsional interactions described by Bunker and di Lauro to determine spectroscopic constants for the upper C-H stretching state and for the Fourier components of the torsional potential in the ground and excited states. The results yield the value $6.316\times 0.034$ $cm^{-1}$ for the barrier to internal rotation in the ground state, and $6.643\times 0.006$ $cm^{-1}$.for the C-H stretching state. This value for the ground state barrier is somewhat higher than that recently determined from an analysis of the $CH_{3}$-rocking band by Bunker et al.
Description
Author Institution: Department of Physics, Pennsylvania State University; NIST, Pennsylvania State University; J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences