Light-induced conformational transitions of individual molecules in ordered films

The light-induced conformational transformations of naphthacequinone molecules have been studied experimentally and theoretically by varying the wavelength of the optical radiation. Distinctions in the electronic and topologic structures for Langmuir-Schaefer films and for individual molecules during 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) 2000 Elsevier Science Ltd. All rights reserved.