Cross sections σnlfor electron capture collisions between medium velocity, highly charged ions and molecular hydrogen

Abstract
The population of highly excited n, l states in single-electron capture by Au ions of charge state 12-18 and 2 au velocity from molecular hydrogen has been investigated experimentally for 9nl were extracted from measurements of 2000-6000 AA photons emitted after capture. A refocusing technique made possible sufficient resolution for the observation of the different l components of the n to n-1 transitions. A comparison with UDWA and CTMC theoretical calculations for point-like ions colliding with atomic hydrogen shows one of their main conclusions to be true: the preferentially populated states have a high angular momentum. The CTMC l distribution agrees better with the experimental data than does the UDWA result. The validity of the comparison is discussed in detail. As a by-product of the measurement, the dipole polarisabilities of the ions in question were obtained.