The effect of intermolecular interaction on the electronic properties of quaterylene

The electronic and optical properties of quaterylene in controlled concentr ation solutions have been investigated by means of optical absorption, phot oluminescence (PL) and photoluminescence excitation (PLE) spectroscopy. The absolute quantum yields (QY) of photoluminescence for solutions of differe nt concentrations have also been measured using an integrating sphere. The molecule shows a peculiar behaviour compared to those of shorter oligomers of the same family. Optical activity in two well distinct energy region can be seen. We found the low energy absorption and emission to be due to aggr egate formation. We tentatively assign the high energy optical activity to dimer formation.