v. 811

This proceedings volume contains the invited talks presented at two atomic physics symposia held jointly in Buenos Aires, Argentina from 28-30 July 2005. All papers were peer-reviewed. They represent the latest research in dynamics of collision systems involving collisions between photons, electrons, and ions and a diverse range of target species: atoms, molecules, clusters, and surfaces. There is a particular emphasis on correlation and many-body effects in excitation and ionization.