Recoil Ions from Close 20-keV H\u3csup\u3e+\u3c/sup\u3e Collisions with O\u3csub\u3e2\u3c/sub\u3e, CO, CO\u3csub\u3e2\u3c/sub\u3e, and Ne

Recoil ions ejected at 70° from 20-keV proton collisions with O2, CO, CO2, and Ne were analyzed by an electrostatic analyzer. For the molecular targets, only singly ionized ions of oxygen or carbon were detected while in the spectrum of neon ions, Ne+ and Ne2+ were both observed. The absence of O2+, CO+, and CO2+ is due to the fact that the recoil ions detected in this experiment result only from very close collisions with one of the atoms in the molecule resulting in dissociation. A possible explanation for the absence of O2+ and C2+ peaks based on the molecular nature of the targets is proposed