title: Measurements of the complete solvation response of coumarin 153 in ionic liquids and the accuracy of simple dielectric continuum predictions.
abstract: The complete solvation response of coumarin 153 (C153) has been determined over the range 10(-13)-10(-8) s in a variety of ionic liquids by combining femtosecond broad-band fluorescence upconversion and picosecond time-correlated single photon counting measurements. These data are used together with recently reported dielectric data in eight ionic liquids to test the accuracy of a simple continuum model for predicting solvation dynamics. In most cases the features of the solvation response functions predicted by the dielectric continuum model are similar to the measured dynamics of C153. The predicted dynamics are, however, systematically faster than those observed, on average by a factor of 3-5. Computer simulations of a model solute/ionic liquid system also exhibit the same relationship between dielectric predictions and observed dynamics. The simulations point to spatial dispersion of the polarization response as an important contributor to the over-prediction of solvation rates in ionic liquids.
authors.affiliation: Department of Chemistry, The Pennsylvania State University, University Park, PA, USA. maroncelli@psu.edu
authors.forename: Mark
authors.initials: M
authors.lastname: Maroncelli
authors.forename: Xin-Xing
authors.initials: XX
authors.lastname: Zhang
authors.forename: Min
authors.initials: M
authors.lastname: Liang
authors.forename: Durba
authors.initials: D
authors.lastname: Roy
authors.forename: Nikolaus P
authors.initials: NP
authors.lastname: Ernsting
mesh_terms: D003374:Coumarins / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D012995:Solubility; D055672:Static Electricity
chemical_list: D003374:Coumarins; D052578:Ionic Liquids; C488877:coumarin 153