An experimental study of beam-gas collisions, I

Abstract

A He gas target has been bombarded with H +, H 2 +, H 3 +, He +, 20Ne + , 22Ne +, Ar +, 84Kr +, 86Kr +, and Xe + ions with energies ranging from 10 keV to 75 keV. Photons emitted from atoms and ions excited in inelastic collisions or charge exchange processes have been analysed in the spectral range 200 nm to 600 nm. Excitation functions have been measured for some levels in neutral helium at different gas pressures in the single collision region. The excitation was found to depend on the projectile. When using a specific projectile, no correlation has been found between the excitation funtions of levels with different principal quantum number. Furthermore, levels with the same principal quantum number, but different azimuthal quantum number are excited differently. Corresponding singler and triplet levels in neutral He were found to have rather similar excitation functions. The maxima and minima are situated at the same energies, but the extrema are much more pronounced in the excitation functions of singlet levels than for the corresponding triplet levels. The 4d 1D and 4d 3D levels of He I have been excited both with 20Ne + and 22Ne +. The slopes of the corresponding excitation functions are found to be almost identical, but the 22Ne + induced radiation is found to be slightly more intense than (up to approximately 10%) or equal to that induced by 20Ne + at the same centre of mass energy or at the same relative velocity. No measurable differences were found between the 84Kr + and the 86Kr + induced radiation. Many strong lines were emitted from the heavier projectiles.