APPLICABILITY OF A ONE-DIMENSIONAL MODEL FOR STUDYING THE TRANSFER OFEXCITONS IN PYRENE MICROCRYSTALLITES

The experimental results on the exciton transfer obtained in pyrene mi crocrystallites are discussed with the help of a one-dimensional theor y. The excitation spectrum for luminescence observed in pyrene microcr ystallites consists of a sharp line and an exponential tail. Such a ba nd shape is obtained theoretically for a one-dimensional model using t he tight-binding approach. The exciton bandwidth is also calculated fo r the one-dimensional model. The exciton bandwidth observed in small m icrocrystallites was much narrower than that expected from the one-dim ension theory. This discrepancy is explained in terms of experimental sensitivity and forbidden optical transition. We will emphasize that e ven in a molecular array as small as 5 or 6 molecules in it, the conce pt of the exciton propagation is applicable. (C) 1998 Elsevier Science B.V. All rights reserved.