Control of optical properties of polymethine dye <Emphasis Type="Italic">J</Emphasis>-aggregates using different additives

The effect of various additives (NaCl, DNA, and CPB surfactant) on the structure and optical properties of luminescent molecular nanoclusters, J-aggregates of L-21 polymethine dye, has been investigated using stationary and time-resolved optical spectroscopy. It has been shown that all investigated additives enhance the dye aggregation and change its aggregate structure as manifested in a change of tilt angle between molecules in the molecular chain. Salt causes the biggest change of tilt angle whereas surfactant causes the smallest. It has been found that a decrease of tilt angle leads to an increase of J-aggregate luminescence intensity. The addition of CPB surfactant is shown to modify the exciton dynamics in J-aggregates whereas the other additives affect only their structure. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 2, pp. 250–255, March–April, 2009.