PHYS 316 |
| Our description of structural and dynamical aspects of elementary acid dissolution events at the molecular-level progresses steadily due to continuous advances in modeling and experimental techniques. These fundamental processes continue to be scrutinized due to their role in important heterogeneous atmospheric chemistry reactions that are catalyzed by ice. Of the simple hydrogen halide series, studies on the interaction of HF with ice have been few in comparison with those on HCl and HBr. This is partly due to the presumption that given its weak acid behaviour, the interaction of HF with ice should be dominated by straightforward H-bonding between undissociated molecules. We will present recent investigations of HF adsorption uptake, and dissolution using cryogenic binary mixtures of HF and H2O prepared as thin films using molecular beam techniques. The complex features displayed by the experimental reflection-absorption spectra are modeled using Fresnel theory yielding optical constants as a function of sample thickness, composition and temperature. Near quantitative agreement of these empirical data with theoretical results, based on ab initio molecular dynamics simulations of the absorptivity of binary amorphous solids, allow us to provide a complete assignment of the infrared spectra of cryogenic hydrofluoric acid solutions. These observations are compared and contrasted with those made using cryogenic aqueous solutions of the strong acids HCl and HBr. Finally, our findings are discussed in light of the conventional interpretation of why hydrofluoric acid is a weak acid. |
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Hydration: From Clusters to Aqueous Solution
1:20 PM-5:00 PM, Wednesday, August 22, 2007 BCEC -- 159, Oral
Division of Physical Chemistry |