
The rotational dynamics of a polar laser dye coumarin 519 has been studied in alcohols by both steady state and time-resolved fluorescence depolarization technique at room temperature. Rotational correlation times of the probe were found to vary linearly as function of viscosity of the solvents. Results are analyzed by employing the Stokes-Einstein-Debye (SED) hydrodynamic theory to estimate the mechanical friction with slip and stick boundary conditions.