This award supports cooperative research in atomic and molecular physics to be conducted by James McGuire and C.D. Lin of Kansas State University and Roberto Rivarola and Ruben Piacentini of the National University of Rosario, Argentina. This work will involve the development of theoretical models of atomic and molecular collisions. A new class of inelastic processes in atomic collisions with highly charged ions will be investigated. This is made possible by new ion sources, developments in the study of laboratory plasmas and new access to antimatter beams. Inner-shell and outer-shell phenomena will be included and the collision speeds will range from slow to fast with single particle and multiparticle excitations. These scientists have been involved extensively in the development of theoretical models which provide an understanding of new experimental results and on which are based systematics for further experimental tests. This research will build on an increasing cooperation between these scientists beginning in 1981. Both groups published studies of electron capture and initially, contact was made through international meetings and correspondence. In 1988, McGuire and Rivarola collaborated on a study of electron capture from molecules by fast ions and have submitted a joint paper. They have just begun a study of electron distribution in atomic ionization. This grant will formalize the cooperation between them and allow contact with other theorists in both countries.