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Title: Vibrational dynamics of aqueous hydroxide solutions probed using broadband 2DIR spectroscopy

We employed ultrafast transient absorption and broadband 2DIR spectroscopy to study the vibrational dynamics of aqueous hydroxide solutions by exciting the O–H stretch vibrations of the strongly hydrogen-bonded hydroxide solvation shell water and probing the continuum absorption of the solvated ion between 1500 and 3800 cm{sup −1}. We observe rapid vibrational relaxation processes on 150–250 fs time scales across the entire probed spectral region as well as slower vibrational dynamics on 1–2 ps time scales. Furthermore, the O–H stretch excitation loses its frequency memory in 180 fs, and vibrational energy exchange between bulk-like water vibrations and hydroxide-associated water vibrations occurs in ∼200 fs. The fast dynamics in this system originate in strong nonlinear coupling between intra- and intermolecular vibrations and are explained in terms of non-adiabatic vibrational relaxation. These measurements indicate that the vibrational dynamics of the aqueous hydroxide complex are faster than the time scales reported for long-range transport of protons in aqueous hydroxide solutions.
Authors:
 [1] ;  [2] ;  [1]
  1. Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
22493253
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 143; Journal Issue: 19; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION; ABSORPTION SPECTROSCOPY; CHEMICAL BONDS; COMPLEXES; COUPLING; ENERGY TRANSFER; EXCITATION; HYDROGEN; HYDROXIDES; INFRARED SPECTRA; LONG-RANGE TRANSPORT; NONLINEAR PROBLEMS; PROBES; PROTONS; RELAXATION; SOLUTIONS; SOLVATION; TRANSIENTS; WATER