Derivation and interpretation of the spectra of aggregates. Part 5.—Dimers of some xanthene dyes

Abstract

Characteristic visible spectra of the monomeric and dimeric species of Pyronine B in aqueous solution have been obtained. The spectra of the dimeric species of the xanthene dyes Rhodamine B, Pyronine Y and Pyronine B were fitted to, and compared with, theoretical spectra calculated from two excition interaction theories. The existence of a weak coupling arising from the nuclear momenta and predicted by an adiabatic theory of exciton interactions in dimers is confirmed.