Natural radiative lifetimes of anthracene derivatives and their dependence on refractive index

Abstract

Fluorescence lifetimes of the electronic origins of S 1 are measured in supersonic free jets for nine anthracene derivatives. For most of the meso di-substituted derivatives, these lifetimes are virtually equal to the natural radiative lifetimes in vacuum and they are satisfactorily related to the radiative lifetimes determined in n-hexane through a factor of n 2 ( n is the refractive index). This unambiguous relationship found for the anthracene derivatives will help to bring a long-standing debate on the refractive-index dependence of the radiative lifetime to an end. It will also provide a basis for the discussion of the dependence of the radiative lifetime on single vibronic levels (SVL).