Photophysical properties of lycopene organized in Langmuir-Blodgett films: formation of aggregates

Mixed films of lycopene and stearic acid (SA) form highly stable floating monolayers at the air-water interface which may be easily transferred to glass or quartz substrates with a high transfer ratio. The surface pressure vs. area per molecule isotherms indicate that the lycopene molecules have a preferred orientation at the air-water interface. Polarized absorption studies support such an orientation of lycopene molecules in Langmuir-Blodgett (LB) films. Repulsive-type interactions between lycopene and SA have been observed by Gibbs free energy measurements. Spectroscopic studies of lycopene in solution, binary solvents and LB films suggest the formation of both J- and H-type aggregates. (C) 1997 Elsevier Science S.A.