Fluorescence dynamics in supercooled (acetamide plus calcium nitrate) molten mixtures

Fluorescence dynamics of a polar solute probe in molten (CH3CONH2 + Ca(NO3)(2).4.37H(2)O) mixtures have been measured in order to probe the solute-medium interactions in such complex systems. Steady state and time-resolved measurements bear no signatures of mega-value of the static dielectric constant, strong heterogeneity and extremely slow relaxation times reported in dielectric relaxation experiments for these molten mixtures. Subsequent applications of a semi-molecular theory reveal both the solute-medium dipole-dipole and ion-dipole interactions contribute significantly to the measured Stokes' shifts. Calculated average solvation times in the underdamped and overdamped limits of frictional solvent response agree semi-quantitatively with those from time-resolved measurements. (C) 2010 Elsevier B.V. All rights reserved.