Tunneling Splittings for "O...O Stretching" and Other Vibrations of Tropolone Isotopomers Observed in the Infrared Spectrum Below 800 cm-1
Fourier transform infrared absorption spectra containing evidence for about two dozen spectral tunneling doublets are reported for gaseous tropolone(OH), tropolone(OD), and 18O,18O-tropolone(OH) in the 800 to 300 cm-1 spectral range. No FTIR absorption was detected in the 300-150 cm-1 range. The known zero-point (ZP) tunneling splitting values Δ0 = 0.974 cm-1 for tropolone(OH) (Tanaka et al.) and 0.051 cm-1 for tropolone(OD) (Keske et al.) allow vibrational state-specific tunneling splittings Δv to be estimated for fundamentals including three with strong O•••O stretching displacements [cf. for tropolone(OH) ν13(a1) = 435.22 cm-1 with Δ13 = 1.71 cm-1 = 1.76 Δ0, and for tropolone(OD) ν13(a1) = 429.65 cm-1 with Δ13 = 0.32 cm-1 = 6.3 Δ0]. The majority of Δv splittings in the sub-800 cm-1 range are dilated relative to the isotopomer Δ0 values. The FTIR spectra demonstrate the presence of dynamic couplings and potential function anharmonicity in addition to revealing Δv splittings and many 2 OH/D and 18O/16O isotope effects. Approximate values for the ZP splittings 88Δ0 and 86Δ0 of the doubly and singly 18O-labelled isotopomers of tropolone(OH) are obtained. The diverse values of the observed Δv/Δ0 splitting ratios underscore the inherent multidimensionality and the quantum corner-cutting activities entering the state-specific tunneling processes of the tropolone tautomerization reaction.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 926930
- Report Number(s):
- PNNL-SA-56147; 2371a; KP1704020
- Journal Information:
- Journal of Physical Chemistry A, 112(7):1480-1492, Journal Name: Journal of Physical Chemistry A, 112(7):1480-1492
- Country of Publication:
- United States
- Language:
- English
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