Introduction To Atomic And Molecular Collisions

In working with graduate students in engineering physics at the University of Virginia on research problems in gas kinetics, radiation biology, ion materials interactions, and upper-atmosphere chemistry, it became quite apparent that there was no satisfactory text available to these students on atomic and molecular collisions. For graduate students in physics and quantum chemistry and researchers in atomic and molecular interactions there are a large number of excellent advanced texts. However, for students in applied science, who require some knowledge and understanding of col lision phenomena, such texts are of little use. These students often have some background in modern physics and/or chemistry but lack graduate level course work in quantum mechanics. Such students, however, tend to have a good intuitive grasp of classical mechanics and have been exposed to wave phenomena in some form (e. g. , electricity and magnetism, acoustics, etc. ). Further, their requirements in using collision processes and employing models do not generally include the use of formal scattering theory, a large fraction of the content of many advanced texts. In fact, most researchers who work in the area of atomic and molecular collisions tend to pride themselves on their ability to describe results using simple theoretical models based on classical and semiclassical methods.

An understanding of the collisions between micro particles is of great importance for the number of fields belonging to physics, chemistry, astrophysics, biophysics etc. The present book, a theory for electron-atom and molecule collisions is developed using non-relativistic quantum mechanics in a systematic and lucid manner. The scattering theory is an essential part of the quantum mechanics course of all universities. During the last 30 years, the author has lectured on the topics presented in this book (collisions physics, photon-atom collisions, electron-atom and electron-molecule collisions, "electron-photon delayed coincidence technique", etc.) at many institutions including Wayne State University, Detroit, MI, The University of Western Ontario, Canada, and The Meerut University, India. The present book is the outcome of those lectures and is written to serve as a textbook for post-graduate and pre-PhD students and as a reference book for researchers.

An understanding of the collisions between micro particles is of great importance for the number of fields belonging to physics, chemistry, astrophysics, biophysics etc. The present book, a theory for electron-atom and molecule collisions is developed using non-relativistic quantum mechanics in a systematic and lucid manner. The scattering theory is an essential part of the quantum mechanics course of all universities. During the last 30 years, the author has lectured on the topics presented in this book (collisions physics, photon-atom collisions, electron-atom and electron-molecule collisions, "electron-photon delayed coincidence technique", etc.) at many institutions including Wayne State University, Detroit, MI, The University of Western Ontario, Canada, and The Meerut University, India. The present book is the outcome of those lectures and is written to serve as a textbook for post-graduate and pre-PhD students and as a reference book for researchers.

Commencing with a self-contained overview of atomic collision theory, this monograph presents recent developments of R-matrix theory and its applications to a wide-range of atomic molecular and optical processes. These developments include the electron and photon collisions with atoms, ions and molecules which are required in the analysis of laboratory and astrophysical plasmas, multiphoton processes required in the analysis of superintense laser interactions with atoms and molecules and positron collisions with atoms and molecules required in antimatter studies of scientific and technologial importance. Basic mathematical results and general and widely used R-matrix computer programs are summarized in the appendices.

The theory of atom-molecule collisions is one of the basic fields in chemi cal physics. Its most challenging part - the dynamics of chemical reactions - is as yet unresolved, but is developing very quickly. It is here a great help to have an analysis of those parts of collision theory which are already complete, a good example being the theory of atomic collisions in process es specific to chemical physics. It has long been observed that many notions of this theory can also be applied successfully to reactive and unreactive molecular collisions. More over, atomic collisions often represent a touchstone in testing approaches proposed for the solution of more complicated problems. Research on the theory of slow atomic collisions carried out at the Moscow Institute of Chemical Physics has been based on just these ideas. A general viewpoint concerning the setting up and representation of the theory came out of these studies, and appeared to be useful in studying complicated systems as well. It underlies the representation of the theory of slow atomic colli sions in this book.

Since the beginning of the twentieth century, many experimental and theoretical works have been devoted to collisions between highly charged ions and atomic and molecular targets. It was realized that quantum mechanics is the only way, a priori, to describe such atomic phenomena. However, since quantum mechanics is very difficult to apply for collision systems with more than two particles, classical methods were very soon introduced and applied to simple collision systems and, subsequently, to more complicated systems. The results obtained by such classical methods were found to be surprisingly good, and classical mechanics is now well established, despite its approximations, as a replacement for or competition with quantum mechanics in many cases. In this book, the author will focus on the development of classical methods for describing collisional and post-collisional processes. The results will be compared with those found using quantum mechanical models, in order to demonstrate the ability of the classical approach to obtain many features and details of collision systems.