15min:

SYLVESTRE TWAGIRAYEZU, TROCIA N. CLASP, DAVID S. PERRY, Department of Chemistry, The University of Akron, Akron OH 44325; JUSTIN L. NEILL, MATT T. MUCKLE AND BROOKS H. PATE, Department of Chemistry, University of Virginia, McCormick Rd., P.O. Box 400319, Charlottesville, VA 22904.

Rotational state-selection with E-species transitions (3₀ 3_-1,2₀ 3₁,1₀ 1₁) is employed to record the infrared spectra in the range 2750-2900 cm^-1. The observed spectra of CH₃OD contain only one vibrational band origin whereas 12 interacting vibrational bands of CH₃OH are observed in the same interval. There are no interacting vibrational bands in the CH₃OD spectra because the first tier states are shifted out of resonance. This observation confirms that the dominant coupling pathway in the ₃ CH stretch of CH₃OH is the third order coupling of the CH stretch to a combination of the COH bend and an HCH bend, which subsequently couples to high order combination bands involving torsional excitation.