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SYLVESTRE TWAGIRAYEZU, DAVID S. PERRY, Department of Chemistry, The University of Akron, Akron OH 44325; JUSTIN L. NEILL, MATT T. MUCKLE, BROOKS H. PATE, Department of Chemistry, University of Virginia, McCormick Rd., Charlottesville, VA 22904.
Coherence-converted population transfer microwave-infrared double resonance spectroscopy is employed to record the rotationally state-selected infrared spectra of jet-cooled CH3OD in the C-H stretch region (2750-3020 cm-1). The observed infrared spectra result from the E-species microwave transitions (10
1-1 at 18.957 GHz, 20
2-1 at 18.991 GHz, and 30
3-1 at 19.005 GHz). The present spectra of CH3OD contain 17 interacting vibrational bands (J' = 0). In additional to the three C-H stretch fundamentals (
3:2841.7 cm-1,
9:2954.4 cm-1 and
2:2998.9 cm-1), 14 additional band origins are found in the region of the binary combinations of the CH bends (2890-2950 cm-1). Although the A-species was inaccessible in the present work, the pattern of E-species reduced energies suggests that the torsional tunneling splittings of
3 and
9 are normal, whereas
2 is inverted. The number and distribution of the observed vibrational bands support a stepwise coupling scheme in which the CH stretch bright state couples first to the binary C-H bend combinations, and then to all of the higher order vibrational combinations. A time-dependent interpretation in the asymmetric region indicates a fast (170 fs) initial decay of the bright state.