ABSTRACT
In most cases, the data in Table 1 refer to intrinsic bulk processes. For the bisazo compound (Umeda et al., 1990), however, the thermalization distance of 22 A describes an intrinsic process, while 140 A describes a surface-enhanced extrinsic process. In this study, the extrinsic process involves an interaction of a charge transfer state with the donor compound of the transport layer. In the aggregate material (Borsenberger and Hoesterey, 1980), the thermalization distance of 44 A describes a surface-enhanced process involving a donor compound absorbed on the surface of the aggregate phase. In the absence of the donor compound, the thermalization distance is 35 A. The studies of Umeda et al. and Borsenberger and Hoesterey are perhaps the only cases where the Onsager formalism has been applied to surface-enhanced extrinsic processes. The models applied by these authors, however, are based on three-dimensional arguments. It is questionable whether the physical processes described by these models closely correspond to the conditions of the experiments.
