Multidimensional intermolecular dynamics from tunable far-infrared laser spectroscopy: Angular-radial coupling in the intermolecular potential of argon--H sub 2 O

Journal Article · Sun Dec 01 00:00:00 EST 1991 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.461318· OSTI ID:5008695

Cohen, R C; Saykally, R J ^[1]

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1. Department of Chemistry, University of California, Berkeley, California (USA)

Five new vibration--rotation tunneling states of Ar--H{sub 2}O (the {Sigma} and {Pi}(1{sub 11}) and the {Sigma} and {Pi}(2{sub 12}) internal rotor states and the {ital n}=1, {Pi}(1{sub 01}) stretching-internal rotor combination level) have been accessed by tunable far-infrared laser spectroscopy. The measured vibrational band origins of transitions to these states are within 2% of predictions made from an anisotropic three-dimensional intermolecular potential surface (denoted AW1) derived from a nonlinear least-squares fit to previous far-infrared spectral data (J. Phys. Chem. {bold 94}, 7991(1990)). This provides strong evidence that the AW1 intermolecular potential surface incorporates much of the essential physics of the intermolecular forces which bind the cluster. However, larger deviations from the predictions are found in the observed rotational term values. A detailed analysis of these deviations clearly demonstrates the need for even stronger angular-radial coupling in the Ar--H{sub 2}O intermolecular potential than the already substantial coupling present in the AW1 surface. Specifically, the presently observed {Sigma}(1{sub 11}) state and the {ital n}=1, {Sigma}(0{sub 00}) state are found to be approximately 65:35 mixtures of the basis states which represent pure stretching and internal rotation. The {Sigma}(2{sub 12}) level is found to be mixed just as strongly with {ital n}=2, {Sigma}(1{sub 01}). The formalism for accurately deperturbing vibration--rotation--tunneling states coupled by Coriolis interactions used in the above analysis is presented.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5008695
• Journal Information: Journal of Chemical Physics; (United States), Vol. 95:11; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ARGON COMPLEXES
INTERMOLECULAR FORCES
WATER
COUPLING
DYNAMICS
FAR INFRARED RADIATION
LASER SPECTROSCOPY
MANY-DIMENSIONAL CALCULATIONS
ROTATIONAL STATES
TUNNEL EFFECT
VIBRATIONAL STATES
COMPLEXES
ELECTROMAGNETIC RADIATION
ENERGY LEVELS
EXCITED STATES
HYDROGEN COMPOUNDS
INFRARED RADIATION
MECHANICS
OXYGEN COMPOUNDS
RADIATIONS
SPECTROSCOPY
640302* - Atomic
Molecular & Chemical Physics- Atomic & Molecular Properties & Theory