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

Fluorescence dynamics of a polar solute probe in molten (CH3CONH2 + Ca(NO3)2·4.37H2O) 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.