The rotational spectra of benzyl alcohol and of its OD isotopologue have been assigned and measured in a supersonic expansion, either with pulsed-jet Fourier transform microwave or free jet absorption millimeter wave spectroscopy. The spectrum is consistent with a gauche conformation of the oxygen atom, characterized by a θ (OC7-C1C2) dihedral angle of approximately 55°. Such a configuration is 4-fold degenerate, corresponding to minima with θ ≈ (60°, (120°. The four equivalent minima are separated by two kinds of barrier, corresponding to θ ) (90°, and 0 or 180°. Only the θ ) (90° barriers are low enough to generate a tunneling splitting, which has been measured in a spectrum strongly perturbed by tunneling interactions. The observed splittings diminish considerably upon deuterium substitution. The tunneling splittings are consistent with a barrier about 280 cm-1 and high level ab initio calculations predicting a 320 cm-1 barrier.

Rotational Spectrum, Tunneling Motions, and Potential Barriers of Benzyl Alcohol

CAMINATI, WALTHER
2010

Abstract

The rotational spectra of benzyl alcohol and of its OD isotopologue have been assigned and measured in a supersonic expansion, either with pulsed-jet Fourier transform microwave or free jet absorption millimeter wave spectroscopy. The spectrum is consistent with a gauche conformation of the oxygen atom, characterized by a θ (OC7-C1C2) dihedral angle of approximately 55°. Such a configuration is 4-fold degenerate, corresponding to minima with θ ≈ (60°, (120°. The four equivalent minima are separated by two kinds of barrier, corresponding to θ ) (90°, and 0 or 180°. Only the θ ) (90° barriers are low enough to generate a tunneling splitting, which has been measured in a spectrum strongly perturbed by tunneling interactions. The observed splittings diminish considerably upon deuterium substitution. The tunneling splittings are consistent with a barrier about 280 cm-1 and high level ab initio calculations predicting a 320 cm-1 barrier.
K.A. Utzat; R.K. Bohn; J.A. Montgomery Jr.; H. Harvey Michels; W.Caminati
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11585/96589
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