DISTANCE-DEPENDENT ENERGY-TRANSFER BETWEEN INDOLE AND ANTHRACENE MOIETIES IN LANGMUIR-BLODGETT-FILMS

1,2-Diphenyl indole (DPI) and 9,10-diphenyl anthracene (DPA) are non-a mphiphilic molecules but form excellent LB films when mixed with stear ic acid (SA). Spectroscopic investigations of these films indicate for mation of aggregates of DPI and DPA in the mixed LB films. DPA has bee n used as the quencher of the fluorescence of the DPI donor. Distance- dependent energy transfer between donor and acceptor monolayers in the LB film, where they can be precisely separated by inert spacers of st earic acid layers of varied thickness, is shown to satisfy Khun's quad ratic equation. This suggests that the donor excitations are delocaliz ed. The large critical transfer distance estimated from the experiment al results has been attributed to the formation of aggregates of the m olecules in a LB monolayer. (C) 1998 Elsevier Science B.V. All rights reserved.