15min:

EMILY J. GILLES, STEPHEN DRUCKER, Department of Chemistry, University of Wisconsin-Eau Claire, Eau Claire, WI 54702; JAEBUM CHOO, Department of Chemistry, Hanyang University, Ansan 425-791, Korea; DANIEL AUTREY, Department of Natural Sciences, Fayetteville State University, Fayetteville, NC 28301; MOHAMED RISHARD, JAAN LAANE, Department of Chemistry, Texas A & M University, College Station, TX 77843.

The S₁(n, ^*) S₀ cavity ringdown spectrum of 2-cyclohexen-1-one vapor has been recorded in the vicinity of the origin band, which is at 26,089.1 \pm 0.1cm^-1. Observation of hot bands in the spectrum has permitted the determination of several low-frequency fundamentals and overtones in the ground electronic state. The lowest two excited quantum states for the inversion vibration, ₃₉, were found to be at 99.0 and 197.0 cm^-1. Together with previously published far-infrared spectra and vapor-phase Raman spectra, the fundamental frequencies for ₃₇ and ₃₈ have also been established. From observed ₃₉ levels, the barrier to inversion was determined experimentally to be 1900 \pm300 cm^-1, which is very different from values of 935 and 3379 cm^-1 previously reported from Raman and far-infrared data, respectively. Density functional calculations carried out in the present work give a barrier value of 2090 cm^-1 when the B3LYP/6-311 + G(d,p) basis set is used.