One-and two-photon fluorescence excitation spectra of multi-chromophoric molecules

Abstract

The splittings in S1 states of molecules containing weakly coupled π-chromophoric groups have been determined through one-and two-photon fluorescence excitation (OPF and TPF) spectroscopy. The 1B2u state of benzene splits by about 140 cm-1 in the dimer, dihydroanthracene (DHA) and by about 2500 cm-1 in the strained trimer,triptycene (TR). While the exciton splitting in the trans-dimer of acenaphthylene (TDA), in which the two naphthalene moieties are linked by two ethylene bridges, is only 130 cm-1, no such near degeneracies are noticed in two-methylene-bridge-linked dihydrodibenzanthracene (DBA) or dihydropentacene (DHP). © 1988.