Spectroscopic Implications of Partially Quenched Orbital Angular Momentum in the OH−Water Complex

• Published in: The journal of physical chemistry. B Vol. 109; no. 17; pp. 8400 - 8406
• Main Authors: Marshall, Mark D, Lester, Marsha I
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 05.05.2005
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp046308k

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 2A‘ and 2A‘ ‘ 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 2A‘ and 2A‘ ‘ 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.