Electron Capture Into Excited States in Collisions Between Multiply Charged Ions and Atoms

We discuss some recent experimental results on charge transfer into excited states in collisions between multiply charged ions and Li atoms. Beams of He 2+ , C q+ , O q+ ( q = 1, 2, 3) ions in the energy range of (10-200) q keV were crossed with a thermal Li beam produced by an oven. From measurements of the radiation emitted by the decay of the excited ion states we were able to determine absolute cross sections for electron capture into specific n , l -states. The wavelength range covered is about 10-700 nm. For C q+ and O q+ , we also used a molecular hydrogen target. Comparing the results for both targets, we can explain the differences as a result of the difference in ionization potential. The importance of metastable fractions in the C q+ , O q+ ion beams is discussed.