Electron capture by slow multiply charged ions from H(1s)

Abstract

Over the last 11 years a considerable experimental and theoretical effort has been devoted to electron capture collisions involving slow ( v < 1 a.u.) multiply charged ions and atomic hydrogen. These collisions result in the selective population of a relatively small number of excited projectile states. Translational energy spectroscopy (TES) and the complementary technique of photon emission spectroscopy (PES) have been developed to provide state selective cross sections. In the last 5 years the merged beams technique has been used to measure total one electron capture cross sections in the energy range 1–1000 eV amu −1 enabling comparison with theory at much lower energies than was previously possible. The majority of the experimental measurements have been for fully stripped, Li-like or He-like ions. Theoretical models such as the semiclassical close coupling methods and fully quantal molecular orbital methods have been developed in parallel with experiment. In general the agreement is good although there is a need for state selective data at lower energies and for differential experimental measurements. Also experiments are needed with pure ground state or metastable ion beams.