RB03		15min9:04

C. A. ARRINGTON, R. K. FROST, F. C. HAGEMEISTER AND T. S. ZWIER, Department of Chemistry, Purdue University, West Lafayette, IN 47907-1393.

Fluorescence-dip infrared spectroscopy has been employed to record the vibrational spectra of gas phase tropolone and tropolone-OD in the O-H and C-H stretch region for the first time. Tropolone, an pseudo-aromatic ringed system, possesses a symmetric O^{. .}H-O tunneling coordinate which produces a ground state tunneling splitting of 0.99 cm^-1. Use of a two laser depletion scheme allows separate infrared spectra to be recorded for both the lower (a₁ symmetry) and upper (b₂ symmetry) ground state tunneling levels. In each spectrum, a single transition ascribable to the O-H stretch is observed. The (a₁) O-H stretch at 3134.9 cm^-1 is close in energy to the (b₂) O-H stretch observed at 3133.9 cm^-1 indicating that the transitions are to the same excited state tunneling level. Tropolone-OD was investigated in order to identify the C-H stretch vibrations which are close in energy to the red-shifted O-H stretch of tropolone. The spectroscopic results along with recent ab initio calculations are discussed in terms of the hydrogen tunneling motion in tropolone.