ENERGY-TRANSFER AND MIGRATION IN LANGMUIR-BLODGETT-FILMS - MONTE-CARLO SIMULATIONS

Monte Carlo simulations were used to investigate energy migration and transfer in two-dimensional Langmuir-Blodgett films. A general procedure of Monte Carlo simulations of excitation transport is presented and discussed. The results obtained for quantum yields of donor fluorescence, fluorescence depolarization, and donor fluorescence decays reveal two important characteristics. The first is that it is not necessary to include an orientational factor in the description of energy migration and transfer. Second, all of the mentioned photophysical observables are dependent not only on the concentration of molecules but also on the ratio of Forster radii. A comparison with the available theoretical models of excitation transport in two-dimensional structures shows that their agreement with Monte Carlo simulations is satisfactory only at low concentrations. An increase of concentration leads to the situation where the configurations of not only donor molecules but also acceptors which come into play are significant.