This award supports John Tanis and students of Western Michigan University to cooperate with Nikolaus Stolterfoht of the Hahn Meitner Institute in Berlin, Germany. The research will focus on the investigation of double-core vacancy production by ions and photons in three-electron systems. The use of three-electron systems enables a clear interpretation of the results of measurements, and the relative simplicity of the systems lends itself to theoretical analysis. A core vacancy in an atom or ion can occur when an inner-shell electron is excited or ionized through collision with a photon or a charged particle. If two such vacancies are produced in a single collision, the mechanisms for the production of the double-core vacancies can involve electron correlation effects. As a result, the study of such processes gives insight into the atomic structure and collisional dynamics of systems with multiply interacting particles. Complementary facilities and expertise in the German and U.S. groups promise a wide range of new results from various perspectives.
