Laser studies of the dynamics of photodissociation

Abstract

One of the simplest dynamic processes that occurs in chemistry is the photodissociation of a molecule. Molecules are prepared on an excited potential energy surface by a Franck—Condon transition where they then evolve to products. In the process of evolving to products, predissociation can occur so that a new excited state is formed before the dissociation products appear. Other molecules will undergo direct dissociation so that the nascent energy distributions of the products reflect tha characteristics of the original potential energy surface. By measuring the nascent energy distributions of the products and the branching ratios for the production of molecules in different excited states, we can unravel the processes that are occuring within a given system. From these measurements detailed mechanisms can be postulated that explain the photodissociation results. These mechanisms are discussed in terms of kinematic models which illustrate the various types of interactions that occur as excited states evolve toward complete dissociation on a potential energy surface.