Abstract

The nonradiative decay dynamics of crystal violet and other triphenylmethane dyes depend strongly on the nature of the solvent in which they are dissolved. The rate-limiting step of the decay is thought to be barrierless torsional diffusion of the phenyl groups in the excited electronic state. Previous studies of either the fluorescence quantum yield¹ or the ground state bleach recovery² time have found a weak nonlinear viscosity dependence. Recent studies of the excited-state absorption decay time have found a linear viscosity dependence in the n-alcohol series of solvents at constant temperature.³ The results of the first pressure-dependent picosecond study of a triphenylmethane dye in short chain alcohols are reported. This study reveals a linear viscosity dependence over a viscosity range of nearly three decades. Differences between the temperature, pressure, and solvent dependence at low viscosities are discussed.

© 1987 Optical Society of America