Dynamics Of Elementary Gas Phase Reactions

Kinetics and Dynamics of Elementary Gas Reactions surveys the state of modern knowledge on elementary gas reactions to understand natural phenomena in terms of molecular behavior. Part 1 of this book describes the theoretical and conceptual background of elementary gas-phase reactions, emphasizing the assumptions and limitations of each theoretical approach, as well as its strengths. In Part 2, selected experimental results are considered to demonstrate the scope of present day techniques and illustrate the application of the theoretical ideas introduced in Part 1. This publication is intended primarily for working kineticists and chemists, but is also beneficial to graduate students.

The present monograph appears after the death of Professor V. N. Kondratiev, one of those scientists who have greatly contributed to the foundation of contem porary gas kinetics. The most fundamental idea of chemical kinetics, put for ward at the beginning of the twentieth century and connected with names such as W. Nernst, M. Bodenstein, N. N. Semenov, and C. N. Hinshelwood, was that the complex chemical reactions are in fact a manifestation of a set of simpler elementary reactions involving but a small number of species. V. N. Kondratiev was one of the first to adopt this idea and to start investigations on the elementary chemical reactions proper. These investigations revealed explicitly that every elementary reaction in turn consisted of many elementary events usually referred to as elementary processes. It took some time to realize that an elementary reaction, represented in a very simple way by a macroscopic kinetic equation, can be described on a microscopic level by a generalized Boltzmann equation. Neverheless, up to the middle of the twentieth century, gas kinetics was mainly concerned with the interpretation of complex chemical reactions via a set of elementary reactions. But later on, the situation changed drastically. First, the conditions for reducing microscopic cquations to macroscopic ones were clearly set up. These are essentially based on the fact that the small perturbations of the Maxwell-Boltzmann distribution are caused by the reaction proper.

This text gives a concise account of the dynamics and kinetics of elementary reactions in the gas phase, and is structured to emphasize the relationship between thermal rate coefficients and the microscopic mechanisms of chemical reactions.

The chapters in this book are devoted to the elementary reactions of small molecules in the gas phase, with some emphasis on reactions important in combustion. The first three chapters cover experimental measurements made at high temperatures, mainly using shock waves and flames; the final chapter describes discharge flow methods near room temperature. The authors-all active in the fields they describe were asked to aim at a level intermediate between a textbook and a review, designed for readers not already familiar with this branch of chemical kinetics. We hope the book will prove especially useful to research workers in related subjects, to research students, and perhaps as source material for the preparation of lectures. The examples have been chosen to illustrate the theoretical basis of the topics rather than attempt a complete coverage. Professors Wagner and Troe describe the remarkable progress made in recent years in measuring dissociation rates for small molecules. Tests ofunimolecular reaction theories are usually made in the 'fall-off' region of pressure: the kinetics change from first order to second order as the pressure is reduced. For large molecules this region lies below atmospheric pressure and is relatively easily accessible. For molecules with four or less atoms, however, the fall-off region lies well above atmospheric pressure: it has been explored using the high pressure shock tube techniques developed by the authors.

This volume consists of edited papers presented at the International Symposion Gas Phase Chemical Reaction Systems: Experiments and Models 100 Years After Max Bodenslein, held at the Internationales Wissenschaftsforum Heidelberg (IWH) in Heidelberg during July 25-28, 1995. The intention of this symposion was to bring together leading researchers from the fields of reaction dynamics, kinetics, catalysis and reactive flow model ling to discuss and review the advances in the understanding of chemical kinetics about 100 years after Max Bodenstein's pioneering work on the "hydrogen iodine reaction", which he carried out at the Chemistry Institute of the University of Heidelberg. The idea to focus in his doctoral thesis [1] on this reaction was brought up by his supervisor Victor Meyer (successor of Robert Bunsen at the Chemistry Institute of the University of Heidelberg) and originated from the non reproducible behaviour found by Bunsen and Roscoe in their early photochemical investigations of the H2/Cl2 system [2] and by van't Hoff [3], and V. Meyer and co-workers [4] in their experiments on the slow combustion of H2/02 mixtures.

Modeling of Chemical Reactions covers detailed chemical kinetics models for chemical reactions. Including a comprehensive treatment of pressure dependent reactions, which are frequently not incorporated into detailed chemical kinetic models, and the use of modern computational quantum chemistry, which has recently become an extraordinarily useful component of the reaction kinetics toolkit. It is intended both for those who need to model complex chemical reaction processes but have little background in the area, and those who are already have experience and would benefit from having a wide range of useful material gathered in one volume. The range of subject matter is wider than that found in many previous treatments of this subject. The technical level of the material is also quite wide, so that non-experts can gain a grasp of fundamentals, and experts also can find the book useful. A solid introduction to kinetics Material on computational quantum chemistry, an important new area for kinetics Contains a chapter on construction of mechanisms, an approach only found in this book

The aim of this Workshop on "Selectivity in Chemical Reactions" was to examine the specific preferences exhibited by simple chemical reactions with regards to reagents having particular energy states, symmetries, alignment and orientation and the resulting formation of certain products with their corresponding energies, states, alignment and polarisation. Such problems come close to the ultimate goal of reaction dynamics of being able to determine experimentally and theoretically state-to-state cross sections and stereochemical effects under well defined and characterised conditions. There are many examples of highly selective and specific processes to be found in atmospheric and combustion chemistry and the production of population inversions amongst vibrational and electronic states lies at the heart of the development of chemical laser systems. Only when we can understand the fundamental processes that underlie the selectivity in the formation of products in a chemical reaction and the specific requirements of initial states of the reagents, can we expect to be able to develop the explanatory and predictive tools necessary to apply the subject to the development of new laser systems, efficient combustion schemes and specific methods of chemical synthesis, to the control of atmospheric pollution and to all problems in which it is necessary to direct the outcome of a chemical reaction in a specific way. The brief given to the Workshop was to critically review the field, to discuss the present limitations and difficulties and to identify new directions.