Ion-formation total cross sections from dissociative collisions of vibrationally relaxed H-3(+), D-3(+), and HD2+ molecular ions with He

Total cross sections for the positive and negative fragments resulting from dissociative collisions with He of vibrationally relaxed H-3(+), D-3(+), and HD2+ molecular ions have been measured in the energy range 3-9.8 keV. The measured absolute total-cross-section values are more than one order of magnitude smaller than those previously reported with the molecular ions without vibrational relaxation. When the cross sections are plotted as a function of the projectile speed and normalized to compensate for the relative fragment yield, the values for the production of deuterium fragments are higher than those for hydrogen ions in the energy range of the present study. These results are consistent with the theoretical predictions for the behavior of triatomic molecular ions with high rovibrational excitation