10min:

REBECCA A. PEEBLES, SEAN A. PEEBLES, Department of Chemistry, Eastern Illinois University, 600 Lincoln Ave., Charleston, IL 61920; DANIEL A. OBENCHAIN, Department of Chemistry, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459-0180.

The far infrared beamline of the Canadian Light Source synchrotron facility has been used to record three rotationally resolved vibrational bands of 1,1-dichloroethylene in the 500-1000 cm^-1 range, at 0.00096 cm^-1 resolution. These correspond, for the H₂C=C³⁵Cl₂ isotopologue, to an a-type band (CCl₂ antisymmetric stretch) at 796.0 cm^-1, a b-type band (CCl₂ symmetric stretch) at 603.0 cm^-1, and a c-type band (CH₂ wag) at 868.6 cm^-1. Anharmonic frequency calculations at the MP2/6-311++G(2d,2p) level, combined with rotational and centrifugal distortion constants from a millimeter wave study of the ground state\footnote Z. Kisiel, L. Pszczó\l kowski, Z. Naturforsch , \underline\textbf 50a, (1995), 347-351., were an invaluable aid in facilitating the spectroscopic assignment for this asymmetric top ( = -0.58). Analysis of the 796 cm^-1 band is nearly complete, giving well determined excited state rotational and centrifugal distortion constants. Results of this analysis and progress with analysis of the other two bands will be presented.