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Argon Predissociation Spectroscopy of the OH^-·H₂O and Cl^-·H₂O Complexes in the 1000−1900 cm^-1 Region: Intramolecular Bending Transitions and the Search for the Shared-Proton Fundamental in the Hydroxide Monohydrate

Eric G. Diken, Jeffrey M. Headrick, Joseph R. Roscioli, Joseph C. Bopp, and Mark A. Johnson*

Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, Connecticut 06520

Anne B. McCoy*

Department of Chemistry, The Ohio State University, Columbus, Ohio 43210

Xinchuan Huang, Stuart Carter, and Joel M. Bowman*

Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322

J. Phys. Chem. A, 2005, 109 (4), pp 571–575

DOI: 10.1021/jp045612a

Publication Date (Web): January 8, 2005

Abstract

We present argon predissociation vibrational spectra of the OH^-·H₂O and Cl^-·H₂O complexes in the 1000−1900 cm^-1 energy range, far below the OH stretching region reported in previous studies. This extension allows us to explore the fundamental transitions of the intramolecular bending vibrations associated with the water molecule, as well as that of the shared proton inferred from previous assignments of overtones in the higher energy region. Although the water bending fundamental in the Cl^-·H₂O spectrum is in very good agreement with expectations, the OH^-·H₂O spectrum is quite different than anticipated, being dominated by a strong feature at 1090 cm^-1. New full-dimensionality calculations of the OH^-·H₂O vibrational level structure using diffusion Monte Carlo and the VSCF/CI methods indicate this band arises from excitation of the shared proton.