Raman Spectroscopy Study of Solvation Structure in Acetonitrile/Water Mixtures
Technical rept. Jun 1990-May 1991
UTAH UNIV SALT LAKE CITY DEPT OF CHEMISTRY
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Raman spectroscopy is used to probe the CN stretching frequency of acetonitrile as a function of concentration in water. The CN band is modeled as the sum of two Gaussians. The concentration dependence of area and width for each of the Gaussian components provides experimental support of an equilibrium between two forms of acetonitrile in solution. In addition, the concentration dependence of each of the bands correlates well with the thermodynamically related Kirkwood-Buff integrals. The frequency shift of the CN band exhibits a linear dependence on the dielectric constant of protic solvents. There has been considerable effort to define and understand the fundamental molecular interactions important in liquid chromatography . Although the solvophobic theory is commonly invoked to explain retention in reversed-phase liquid chromatography RPLC, recent studies have pointed out shortcomings in this model.
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