NATURAL RADIATIVE LIFETIMES OF ANTHRACENE-DERIVATIVES AND THEIR DEPENDENCE ON REFRACTIVE-INDEX

Fluorescence lifetimes of the electronic origins of S1 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 n2 (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). © 1990.