Coherence and Correlation in Atomic Collisions


Book Description

H. KLEINPOPPEN AND J. F. WILLIAMS It has only very recently become possible to study angular correlations and coherence effects in different areas of atomic collision processes: These investigations have provided us with an analysis of experimental data in terms of scattering amplitudes and their phases, of target parameters such as orientation, alignment, and state multipoles, and also of coherence parameters (e. g. , the degree of coherence of excita tion). In this way the analysis of electron-photon, ion-photon, atom-photon, or electron-ion coincidences from electron-atom, ion-atom, or atom-atom collisional excitation has led to a breakthrough such that the above quantities represent most crucial and sensitive tests for theories of atomic collision processes. Similarly, the powerful (e, 2e) experiments (electron-electron coincidences from impact ionization of atoms) have attracted much attention where improved experimental studies and detailed theoretical description provide a wealth of information on either the col lisional ionization process or the atomic structure of the target atom. Interference effects, many-electron correlations, and energy and angular momen tum exchange between electrons in a Coulomb field playa decisive role in the under standing of postcollision interactions. New results on coherence effects and orienta tion and alignment in collisional processes of ions with surfaces and crystal lattices show links to relevant interference phenomena in atomic collisions. In small-angle elastic electron-atom scattering the effect of angular coherence can be studied in a crossed beam experiment.










Fundamental Processes in Energetic Atomic Collisions


Book Description

In recent years, the impact of new experimental techniques (e.g., nuclear physics methods, availability of high-intensity light sources) as well as an increasing demand for atomic collision data in other fields of physics (e.g., plasma physics, astrophysics, laser physics, surface physics, etc.) have stimulated a renewed, strong interest in atomic collision research. Due to the explosive development of the various fields, scientists often even have dif ficulty in keeping up with their own area of research; as a result, the overlap between different fields tends to remain rather limited. Instead of having access to the full knowledge accumulated in other fields, one uses only the small fraction which at the moment seems to be of immediate importance to one's own area of interest. Clearly, many fruitful and stimulating ideas are lost in this way, causing progress to be made much more slowly than it could be. Atomic col lision physics is no exception to this rule. Although it is of basic interest to many other areas, it is mostly regarded merely as a (nonetheless important) tool by which to gain additional information.




Correlation And Polarization In Electronic And Atomic Collisions - Proceedings Of The International Symposium


Book Description

This volume contains the invited papers delivered at the International Symposium on Correlation and Polarization in Electronic and Atomic Collisions. Experts in the field give the current state and outline future directions of research providing a better fundamental understanding of electron-atom and atom(ion)-atom interactions. Correlation and coherence effects in inelastic collisions as manifested by the observation of photon polarization and photon and particle angular distributions are discussed together with spin dependent effects using spin polarized electron beams.







New Technical Books


Book Description




Coherence in Atomic Collision Physics


Book Description

During the last two decades the experimental investigation of atomic coherence phenomena has made rapid progress. Detailed studies have been performed of angular correlations, spin polarization effects, angular momen tum transfer, and the alignment parameters which characterize the charge cloud of excited atoms. The enormous growth in the number of these investigations was made possible through substantial development and application of new experimental technology, the development of sophisti cated theoretical models and numerical methods, and a fine interplay between theory and experiment. This interplay has resulted in a deeper understanding of the physical mechanisms of atomic collision processes. It is the purpose of the chapters in this book to provide introductions for nonspecialists to the various fields of this area as well as to present new experimental and theoretical results and ideas. The interest in spin-dependent interactions in electron-atom scattering has a long history; it dates back to the early investigations of Mott in 1929. While the more traditional measurements in this field were concerned with the determination of spin polarization and asymmetries, the range of investi gations has been expanded enormously during the last few years and now includes many observables sensitive to one or more of the various spin dependent interactions. The understanding of these effects requires a theoretical description of the orientation and alignment parameters of the target atoms, of the forma tion of resonances, of the influence of electron-exchange processes, and of the relativistic interactions inside the atom and between projectile and target.







Electronic and Atomic Collisions


Book Description