Spectroscopic characterization of aggregation behavior in hemicyanine dye monolayer and multilayer systems

Abstract

The aggregation behavior of the hemicyanine dye N-(3-sulfopropyl)-4-(p-(dioctylamino)styryl)pyridinium, fabricated in Langmuir-Blodgett (LB) monolayer and multilayer systems and directly physisorbed onto quartz substrates has been studied by absorption and fluorescence spectroscopy. The LB monolayer films prepared on quartz substrates show entirely H-aggregate structures, characterized by a large blue-shifted (ΔE∼9000 cm -1 ) electronic transition at 340 nm, not only for the pure-dye system but also for the dye diluted in stearic acid at molar ratios down to 17%. The LB multilayer systems with pure dye show an identical absorption band (340 nm) to the LB monolayers