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Unraveling torsional bath interactions with the CO stretching state in methanol.

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Title: Unraveling torsional bath interactions with the CO stretching state in methanol.
Authors: Pearson, John C.1 John.C.Pearson@jpl.nasa.gov, Daly, Adam M.1, Lees, Ronald M.2
Source: Journal of Molecular Spectroscopy. Dec2015, Vol. 318, p70-77. 8p.
Subjects: Carbon monoxide, Stretching of materials, Methanol, Manifolds (Mathematics), Quantum mechanics
Abstract: Quantum mechanical models describing the effects of a C 3 internal rotor have been successful in modeling all the torsional manifolds of isolated vibrational states. However, modeling the coupling between nearly degenerate small amplitude vibrations in the C 3 internal rotation case remains far from satisfactory and a variety of practical and fundamental questions persist on basis sets, the relative importance of effects and how the problem should be approached. The ν 8 C–O stretching state of methanol has been well studied with infrared techniques and has the potential to serve as an experimental reference data set for the development of models for the coupled large and small amplitude motion case. A combined infrared-microwave study of the lowest K A-states of v t = 3, v t = 4 and ν 8 has been performed to understand the nature of the interactions between ν 8 the excited torsional states. The interaction between v t = 4 and ν 8 at K = 0 + has been confirmed to be Fermi type with magnitude of 2.5 cm −1 . Additionally, the fundamental a -symmetry and b -symmetry Coriolis interactions between v t = 3 and ν 8 have been estimated to be 8900 MHz and −360 MHz, respectively. The magnitude of these interactions suggests that modeling the ν 8 state, the v t = 3 state, and the v t = 4 states will have to carefully account for these interactions. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:Quantum mechanical models describing the effects of a C 3 internal rotor have been successful in modeling all the torsional manifolds of isolated vibrational states. However, modeling the coupling between nearly degenerate small amplitude vibrations in the C 3 internal rotation case remains far from satisfactory and a variety of practical and fundamental questions persist on basis sets, the relative importance of effects and how the problem should be approached. The ν 8 C–O stretching state of methanol has been well studied with infrared techniques and has the potential to serve as an experimental reference data set for the development of models for the coupled large and small amplitude motion case. A combined infrared-microwave study of the lowest K A-states of v t = 3, v t = 4 and ν 8 has been performed to understand the nature of the interactions between ν 8 the excited torsional states. The interaction between v t = 4 and ν 8 at K = 0 + has been confirmed to be Fermi type with magnitude of 2.5 cm −1 . Additionally, the fundamental a -symmetry and b -symmetry Coriolis interactions between v t = 3 and ν 8 have been estimated to be 8900 MHz and −360 MHz, respectively. The magnitude of these interactions suggests that modeling the ν 8 state, the v t = 3 state, and the v t = 4 states will have to carefully account for these interactions. [ABSTRACT FROM AUTHOR]
ISSN:00222852
DOI:10.1016/j.jms.2015.08.008