Photo-induced Cooperative Phenomena in Organic and Inorganic Crystals. A Case of .PI.-Conjugated Polymer: Polydiacetylenes.

Abstract

The review of the photo-induced cooperative phenomena observed in a polydiacetylene (PDA) single crystal is reported. Recently extensive studies have been made on the photo-induced cooperative phenomena, especially photo-induced phase transition, because they are typical examples of the cooperative phenomena under non-equilibrium condition. Here, we report various characteristics of the photo-induced cooperative phenomena and its dynamics after the irradiation of the nanosecond pulsed laser light on the surface of PDA crystal as a typical example. The observed phase conversion efficiency has shown the clear threshold-like behavior. In addition, we also report the conversion dynamics with varying temperatures, excitation intensities and excitation photon energies. The obtained results clearly indicate that thecooperative electron-lattice interaction plays a key role in the dynamical process of the photo-induced phase conversion in PDA crystals.