Spectroscopic investigation of mixed LB films of benzo(k)fluoranthene

This communication reports the spectroscopic studies of nonamphiphilic benzo(k)fluoranthene, abbreviated as BFL, when incorporated into Langmuir-Blodgett (LB) films mixed with stearic acid (SA). The surface pressure versus area per molecule isotherms of BFL mixed with SA at different mole fractions reveals that the area per molecule decreases with increasing mole fractions of BFL. The area per molecule versus mole fraction shows that there is positive deviation of the experimental data to the idealized one. This indicates formation of aggregation of BFL molecules in the mixed LB films with SA. Formation of J-type aggregates has been confirmed by the absorption spectroscopic study. Aggregation of BFL molecules giving rise to excimeric emission has been demonstrated by the fluorescence spectroscopic study. Changing the mole fraction and number of layers as well as the pressure of lifting can precisely control the order of aggregation. This has been reported in detail., (C) 2001 Elsevier Science.