Energy transfer and orientational dynamics in isotropic and nematic phases. A computer simulation approach

We present a computer simulation study of the effect of molecular reorienta tion on the Forster-type energy transfer (ET) process in a nematic and isot ropic phase. Monte Carlo (MC) equilibrium cofigurations and a stepwise diff usion algorithm are employed to model the ET process and the molecular rota tional dynamics in the case of arbitrary time scales. We find faster fluore scence depolarization at higher rotational dynamic rates, but the transfer efficiency and directionality observed for fixed molecules is also maintain ed in the presence of molecular reorientation. (C) 2001 Elsevier Science B. V. All rights reserved.