Low-temperature kinetics of exciton-exciton annihilation of weakly localized one-dimensional Frenkel excitons

We present results of numerical simulations of the kinetics of exciton-exci ton annihilation of weakly localized one-dimensional Frenkel excitons at lo w temperatures. We find that the kinetics is represented by two well-distin guished components: a fast short-time decay and a very slow long-time tail. The former arises from excitons that initially reside in states belonging to the same localization segment of the chain, while the slow component is caused by excitons created on different localization segments. We show that the usual bimolecular theory fails in the description of the behavior foun d. We also present a qualitative analytical explanation of the nonexponenti al behavior observed in both the short- and the long-time decay components. Finally, it is shown that our theoretical estimate for the annihilation ti me of the fast component is in good agreement with data obtained from trans ient absorption experiments on J-aggregates of pseudoisocyanine. (C) 2001 A merican Institute of Physics.