Rotational diffusion of stilbene in alkane and alcohol solutions

Abstract

An amplified colliding pulse modelocked laser system is described which is capable of subpicosecond resolution flash-photolysis studies. As an application of this system we used the anisotropic absorption technique (polarization spectroscopy) to measure the rotational reorientation of trans-stilbene. These measurements give a more accurate estimate of the microscopic friction involved in the isomerization dynamics of this molecule. When the friction is assumed proportional to the reorientation times, the isomerization rates in alkane solvents are adequately described by activated barrier-crossing theory.