Dynamical response in methanol-chloroform binary solvent mixture over fs-μs time regime.

The present study elucidates the extended nature of the weak interaction between methanol and chloroform in its mixture using steady-state, ultrafast and single molecule spectroscopic methods. UV-vis absorption spectroscopy using a solvatochromic dye indicates a synergistic solvation in the methanol-chloroform binary solvent mixture, which causes the solvatochromic dye to sense increased polarity compared to the bulk counterparts. Such synergism was not observed in the emission study and is explained by the weak nature of the interaction between methanol and chloroform. Fluorescence anisotropy and single molecule fluorescence spectroscopy are employed to understand the nature of such weak interaction on femtosecond to microsecond time scale. Retardation of both the rotational and translational diffusion of the reporter molecule indicates that the observed weak interaction is extended over large dimension in the condensed phase. [ABSTRACT FROM AUTHOR]