This cooperative research award supports Jon Levin, Ivan Sellin, and students from their group at the University of Tennessee-Knoxville to collaborate with Dr. Henrik Cederquist of the Physics Department at Stockholm University, Sweden. When an atomic ion in an excited state collides with a neutral atom, the resulting change of state of the incoming ion can be radiated away as a photon, or transferred to the neutral atom causing it to ionize (Penning radiation). The U.S. group has developed an experimental technique that can, for the first time, separate the radiative and non-radiative contributions to the total cross section for quenching of the excited ion. This new technique can measure branching rations and partial rates. The Swedish group, which has world-class expertise in this area, will participate in extending the experiments to include several species of atom and molecule not yet used as targets.
