High pressure luminescence of indole and substituted indoles in liquid solution

Abstract

High pressure luminescence measurements have been made on indole, 5-methoxyindole, and tryptophan in a number of solvents. Radiative and nonradiative rates have been calculated as a function of pressure. It has been shown that the nonradiative rates are determined by viscosity in all solvents except water and, to some extent, methanol for which the peak shift as well as possibly viscosity are the controlling factors. The radiative rates and the peak position and shift have been scaled with the dielectric constant in a continuous and consistent way. Some peculiarities have been observed when water and methanol are used as solvents.