Total yield and angular distribution of highly excited hydrogen atoms formed in Mg, C₈F₁₆, H₂O and H₂targets

The population was measured of the highly excited states (n=10 to 15) in a beam of atoms formed by passing D 1 + , D 2 + ions through Mg, C 8 F 16 , H 2 O and H 2 targets. Ion energies were in the range from 10 keV to 80 keV. An angular dependence of the population was found both for atomic ions and molecular ions incident on the target. In each case the population increased strongly with angle. The total yield of excited atoms was obtained by integration over all angles and it was found that the total yield in H 2 and C 8 F 16 increased with decreasing energy at the lowest energies (10 keV D + ), whereas the yield from H 2 O and Mg targets did not show this effect. Possible reasons for the energy dependence and angular distributions are presented.