Ultrafast Molecular Reaction Dynamics in Real-Time: Progress Over a Decade

Abstract

One of the goals of researchers in the field of reaction dynamics is to develop an understanding of the elementary steps involved in a chemical reaction on a molecular level (see e.g. Ref. 1). The century-old Arrhenius rate law, a phenomenological description of the temperature dependence of rates of reactions in bulk, has been used extensively to deduce activation energies and frequency factors. The activated complex theory (also referred to as absolute rate theory or transition-state theory, see e.g. Refs. 2, 3) postulated more than 50 years ago, provides a useful interpretation of the Arrhenius rate parameters in terms of molecular properties. These parameters contain practical information about rates, but they do not express the molecular details of a reaction. At this juncture, two types of questions can be raised--one concerning the effects of the environment on rates in condensed media, and the other, the purely molecular aspects of reactions in the absence of an environment, i.e. in an isolated molecular system. We restrict our attention to the latter case for the purposes of this review.