Light-induced conformational transitions of individual molecules in ordered films

The light-induced conformational transformations of naphthacequinone molecu les have been studied experimentally and theoretically by varying the wavel ength of the optical radiation. Distinctions in the electronic and topologi c structures for Langmuir-Schaefer films and for individual molecules durin g light-induced transition have been observed. A theoretically model based on the investigation of relaxation of a driven nonlinear oscillator in the presence of tunnelling transitions between different quasienergy states has been suggested to explain the observed conformational transitions. (C) 200 0 Elsevier Science Ltd. All rights reserved.