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Updated: Nov 21, 2025

High-Resolution Neutron Spectroscopy to Study Picosecond-Nanosecond Dynamics of Proteins and Hydration Water
Published on: April 28, 2022
Spectroscopic implications of partially quenched orbital angular momentum in the OH-water complex
Mark D Marshall1, Marsha I Lester
1Department of Chemistry, Amherst College, P.O. Box 5000, Amherst, Massachusetts 01002-5000, USA.
Abstract:
The OH monomer orbital angular momentum is predicted to be partially quenched in the OH-water complex because of the significant splitting of the OH monomer orbital degeneracy into (2)A' and (2)A' ' electronic states. This orbital angular momentum quenching and the associated decoupling of the electron spin from the a inertial axis are shown to have dramatic effects on the rotational band structure of the microwave and infrared transitions of the OH-water complex. At the ab initio values for the splitting between the (2)A' and (2)A' ' surfaces, simulated spectra of a- and b-type bands, such as those expected for the OH radical stretch and water asymmetric stretch, are predicted to have a noticeably different appearance than the well-established limiting cases associated with fully quenched or completely unquenched orbital angular momentum. Spectral identification of the OH-water complex in the gas phase will require explicit consideration of this quenching phenomenon.
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