‘Excimer’ fluorescence I. Solution spectra of 1:2-benzanthracene derivatives

Abstract

Observations have been made of the concentration dependence of the fluorescence spectra of solutions of 1:2-benzanthracene and fifteen of its hydrocarbon derivatives. All of the compounds, except the 9,10-dimethyl derivative, exhibit dimer emission at higher concentrations. The lower excited states, $^1$L$_b$ and $^1$L$_a$, satisfy Forster's conditions for fluorescent dimer formation. The factors determining the relative quantum yield of excimer fluorescence are discussed. The different types of crystal fluorescence spectra shown by the compounds are explained in terms of excimer formation in the crystal lattice.