Dark states in 4,4'-bis(diphenylamino)stilbene-based dendrimers studied by three-photon absorption

Summary form only given. In our recent study of 4,4'-bis(diphenylamino)stilbene-based dendrimers we have found that in contrast to parent, DPAS molecule, the dendrimers possess dark states, lying lower in energy than the first S/sub 0/ - S/sub 1/ transition. In three photon absorption (3PA) measurements, we use fluorescence method and femtosecond pulses, which give intrinsic values of 3PA cross-section. 3PA spectra were obtained by tuning an optical parametric amplifier.