Photoinduced nucleation theory in one-dimensional systems

Photoinduced nucleation of a kink-antikink pair in a one-dimensional system is investigated theoretically, using a model composed of localized two-level electrons and classical lattices, which has two structural phases. We treat the case of the finite-ranged intersite interaction, in order to discuss the crossover from short-ranged to long-ranged interaction. In particular, we focused on the structural change induced by a one-site photoexcitation. When a single site is excited, a local structural change is created around the excited site at first. After the emission of a photon from the excited site, this local structural change (a) remains local, (b) grows into a kink-antikink pair, or (c) disappears and the system returns to the initial phase. Nucleation of a kink-antikink pair occurs only when the intersite interaction is short ranged and moderately strong. The motion of the links is also examined.[S0163-1829(98)03046-X].