Abstract

Solvation dynamics has been extensively studied in the past decade using time resolved luminescence (TRL) techniques [1]. Large polar molecules embedded in polar liquids exhibit a broad and featureless electronic optical spectra. For such molecules, there is a hierarchy of relaxation times of the vibronic transition under consideration [2]: ${\text{σ}}_{\text{2}}^{\text{-1/2}}{\text{<}{\text{T}}^{\prime }\text{<τ}}_{\text{C}}$. Here ${\text{σ}}_{\text{2}}^{\text{-1/2}}$ plays the role of the reversible dephasing time of a vibronic transition, σ₂ is the second central moment of a spectrum corresponding to the vibronic transition, τ_C is the vibrational relaxation time, and ${\text{T}}^{\prime }={\left({\text{τ}}_{\text{C}}{\text{σ}}_2^{\text{-1}}\right)}^{1/3}$. The experimental conditions of our transient degenerate four-wave mixing experiment have been chosen to provide similar information to the ones given by time-resolved luminescence studies. TRL experiments investigate the hot luminescence processes occurring after the completion of the electronic transition phase relaxation (with a characteristic decay time T′) and during the vibrational and solute-solvent relaxation in the excited electronic state.

© 1994 Optical Society of America