During the last two decades the explorations of di?erent processes accom- nyingionatom collisions athigh-impactenergieshavebeenasubjectofmuch interest. This interest was generated not only by the advent of accelerators of relativistic heavy ions which enabled one to investigate these collisions in an experiment and possible applications of obtained results in other ?elds of physics, but also by the variety of physical mechanisms underlying the atomic collisional phenomena at high impact energies. Often highly charged projectiles produced at accelerators of heavy ions are not fully stripped ions but carry one or more very tightly bound el- trons. In collisions with atomic targets, these electrons can be excited or lost and this may occur simultaneously with electronic transitions in the target. The present book concentrates on, and may serve as an introduction to, th- retical methods which are used to describe the projectileelectron transitions occurringinhigh-energycollisionsbetweenionsandneutralatoms.Special- tention is given to relativistic impact energies and highly charged projectiles. Experimental results are used merely as illustrations and tests for theory. This book will be useful to graduate students and professional scientists who are interested in studying atomic collisions occurring at high-impact - ergies. It assumes that the reader possesses the basic knowledge in classical electrodynamics and nonrelativistic and relativistic quantum mechanics.

Nonrelativistic Collisions.- First Order Considerations.- Considerations Beyond First Order Perturbation Theory.- Relativistic Collisions.- to Relativistic Collisions.- Descriptions of Collisions Within the First Order Approximation in the ProjectileTarget Interaction.- Theoretical Methods Extending beyond the First Order Approximation.- Impact Parameter Dependence of Projectile-Electron Excitation and Loss in Relativistic Collisions.- Cross Sections and Comparison with Experiment.