Hole-burning spectroscopy of polar molecules in polar solvents: solvation dynamics and vibrational relaxation

The time- and frequency-resolved hole-burning line shape of polar molecules in a polar solvent is expressed in terms of gas-phase spectroscopic parameters of the solute, vibrational relaxation rates, dielectric properties of the solvent, and the temporal profile of the pump pulse. At short times, a progression of narrow vibronic holes is predicted. As a consequence of solvent relaxation, these holes broaden and undergo a red shift. This behavior has been observed in the measurements of Shank et al. on cresyl violet in ethylene glycol. We propose hole burning as an alternative to fluorescence measurements in probing solvation dynamics.