Preface For Chemical Reaction
Chemical reaction dynamics research has been an important field in physical chemistry and chemical physics research during the last few decades. This field of research has provided crucial support for atmospheric chemistry, interstellar chemistry as well as combustion chemistry. The development in this field has also greatly enhanced our understanding of the nature of bimolecular and unimolecular chemical reactions, and intermolecular and intramolecular energy transfer processes. Even though this field of research reached relative maturity in the 1980s, it has made tremendous progress during the last decade or so. This is largely due to the development of many new and state-of-the-art experimental and theoretical techniques during that period. In view of these significant developments, it is beneficial to all of us that these developments be presented in a review volume to provide both graduate students and experts in the field a detailed picture of the current status of the advanced experimental and theoretical researches in chemical reaction dynamics. This review volume, published in two parts, is dedicated to the recent advances, both theoretical and experimental, in chemical reaction dynamics. All chapters in these books are written by world experts in the chosen special topics.
Experimentally, many new techniques have been developed in the last decade or so to study molecular reaction dynamics. For example, the velocity map imaging method for photochemistry and bimolecular reactions, the high resolution highly sensitive H-atom Rydberg tagging time-of-flight technique, the Doppler selected "core" mapping method, the significantly improved universal crossed molecular beam technique, the coincident imaging method, etc. The application of VUV synchrotron radiation as well as the soft ionization using traditional electron impact ionization in chemical dynamics has somewhat added species selectivity to the study of bimolec-ular as well as unimolecular reactions. The exciting research field of femtosecond chemistry has also provided us the technique and the drive to look at chemical reactions in the real time domain. These experimental methodologies are crucial for the advancement of our detailed understanding of the mechanisms of elementary chemical processes, complicated chemical reactions with multiple reaction pathways, photoionization/photodissociation processes, as well as intermolecular and intramolecular energy transfer processes.
On the theoretical front, the fast growing computing power and the development of sophisticated quantum, semiclassical and statistical methods in this research field allows us now to study complicated chemical processes quantitatively. The development of ab initio quantum chemistry has provided us with tools for obtaining accurate energetics as well as structural information on both small and large molecular systems. Based on ab initio calculations, global potential energy surfaces can now be constructed for elementary chemical reactions for high-level dynamical studies. Dynamical calculations using exact full quantum methods as well as semiclassical methods can be carried out on these global potential surfaces. Combining these calculations with detailed analysis of the calculated results, mechanisms of elementary chemical reactions can now be studied in great detail. Interesting nonadiabatic dynamics involving interesting avoided crossings as well as conical intersections can now be studied using both quantum chemical and dynamical methods. Dynamics of larger systems such as large clusters and biomolecules can also be investigated. Furthermore, the interaction between experiment and theory is becoming stronger than ever. Experiment and theory can now be compared quantitatively in chemical dynamics even for very complicated systems. Such interactions have also enhanced our understanding in almost every front in this research field.
In this second part, we have included a total of ten chapters which describe a variety of new research topics in the chemical dynamics field. Lee and Liu discusses in Chapter 1, a three-dimensional velocity mapping approach to study dynamics in elementary chemical reactions. In Chapter 2, Chao and Skodje provides an overview of the effect of reactive resonance on observables in reactive scattering studies. Chapter 3 by Yang describes the recent advances in the studies of elementary chemical reactions using the Rydberg tagging H-atom transitional spectroscopy technique. Huang et al. in Chapter 4 gives a detailed description on the new multimass ion imaging technique for photochemistry studies. Schroden and Davis describes in Chapter 5 the recent dynamics studies of neutral transition metal atom reactions with small molecules using crossed molecular beam method. The elegant study of photodissociation dynamics of ozone using ion imaging technique in the Hartley band is described in Chapter 6 by Houston. In Chapter 7, Casavecchia et al. focuses on the universal crossed molecular beam reactive scattering studies by soft electron-impact ionization. Wodtke describes in Chapter 8 the dynamics of interactions of vibrationally-excited molecules at surfaces. D. Zhang et al. provides an overview on the recent advances of the first principles quantum dynamical study of four-atom reactions in Chapter 9. In the last chapter, J. Zhang gives an overview on the recent studies of photodissociation dynamics of free radicals. These chapters represent the most recent advances in the various topics in the chemical dynamics research field.
We want to take this opportunity to thank all the authors who have contributed to these two parts in various research topics. We hope these contributions will provide a general view on the current trends in chemical dynamics research, and will be helpful to both experts and newcomers in the field. We appreciate very much the great efforts made by Ms. Ying Oi Chiew who has done a superb job in editing the books.
Xueming Yang and Kopin Liu September 2004
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