INFRARED SPECTRUM OF PROTONATED ACETYLENE
Loading...
Date
1985
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
We have observed some 300 lines which are most likely due to protonated acetylene $H_{2}CCH^{+}$. The band origin is at $3141.4 cm^{-1}$. The rotational structure of the band fits approximately to a parallel ($\Delta K_{a} = 0$) band of the $H_{2}CO$-type classical structure but does not fit well to the usual asymmetric rotor pattern for high J levels. This is probably due to the theoretically predicted existence of the other (non-classical) structure and the very low barrier separating $them^{1,2,3}$. Based on the ab-initio prediction by Raine and $Schaeffer^{3}$, we assign the band tentatively to the CH stretching mode of the classical structure. The possibility of tunneling protons between the two equivalent classical forms through the non-classical form causes the ``splitting” of levels. When the whole problem is treated by using $D_{6h}$ symmetry, the ``internal rotation” around the c-axis is also feasible.
Description
$^{1}$J.A. Pople, Proceedings of the Robert A. Welch Foundation, XVI. Theoretical Chemistry, Houston, Texas (1973). $^{2}$J. Weber, M. Yoshimine and A.D. McLean, J. Chem. Phys. 64, 4159 (1976). $^{3}$G.P. Raine and H.F. Schaefer III, J. Chem. Phys. 81, 4034 (1984).
Author Institution: Department of Chemistry, The University of Chicago; Department of Chemistry, The University of Chicago
Author Institution: Department of Chemistry, The University of Chicago; Department of Chemistry, The University of Chicago