DYNAMICS OF A PHOTOINDUCED PHASE-TRANSITION IN POLYDIACETYLENE CRYSTALS

The dynamical process of the photoinduced phase transition in polydiac etylene (PDA) single crystals has been investigated by time-resolved s pectroscopy with varying temperature, excitation photon energy, and in tensity. The photoinduced phase transition can be driven bidirectional ly between the two (A and B) phases by dichromatic irradiation of a la ser pulse, when the temperature of the PDA crystal is kept around the phase transition temperature (T-c). It was found that primary process of the photoinduced phase transition is mostly completed within 50 ns. In addition, occurrence of a transient domain injection has been conf irmed at temperatures far below and above T-c. Together with the time- resolved measurement of photocurrent, we have found a close correlatio n between the photocurrent intensity and the phase conversion efficien cy. This suggests that the domain walls separating the A and B phases can carry the charge.