Dynamical processes of photo-polymerization and isomerization

Abstract

A simple model of photo-induced structure changes is presented to understand, from a unified viewpoint, the processes of photo-polymerization of diacetylene and diolefin crystals and photo-isomerization of polydiacetylene crystals. The stability of an excited cluster is discussed and the phase diagram is obtained to understand the difference of these processes depending upon materials in terms of the Frank-Condon energy, the electron-lattice coupling constant and the amplitude of lattice mode dispersion. The dynamical properties are studied by making numerical simulations for the one-dimensional chain. We find that it is possible to write analog information into memory in a certain range of the Franck-Condon energy and the response time has a very sharp peak at the value of parameters where the amplification rate of the excited cluster depends strongly on the power of excitation light pulse. This model will give us a guiding principle to look for and design new materials for optical memory.