Stoßdissoziation von H ⁺₂ - und D ⁺₂ -Ionen

Abstract

The angular and energy distribution of protons produced by collision-induced dissociations of H ⁺₂ ions with energies of 10 and 20 keV were measured in a parabola spectrograph. From these measurements the velocity distribution of the protons in the center of mass system of the H ⁺₂ ion can be calculated. This gives information about the type, the abundance, and the anisotropy of the processes involved. The most frequent transitions leading to dissociations are the excitation of the 2pσ_u state, the ionisation of the H ⁺₂ ion, the transition into the vibrational continuum, and the electron capture into the 1³ σ ⁺_u state of the hydrogen. It is shown that the cross section for an electronic transition depends on the velocity of the ion, the distance of the nuclei in the ion, the angle between the internuclear axis and the direction of the primary ion beam, and the excitation energy of the target. The fraction of protons produced by vibrational excitation increases with increasing atomic number of the target. Concerning electronic transitions D ⁺₂ ions equal H ⁺₂ ions of the same velocity.