Recoil-Ion Production from Zero-Impact-Parameter H\u3csup\u3e+\u3c/sup\u3e-Ar and H\u3csup\u3e+\u3c/sup\u3e-Kr Collisions at 20-70 keV

Recoil ions emitted at 70° from H+-Ar and at 50° and 70° from H+-Kr collisions at 20-70 keV were analyzed by an electrostatic spectrometer. Ions selected in this way result from collisions at very small, essentially zero, impact parameters. Charge states up to 6 + were identified in the spectrum. The cross section for each charge state was measured. The data indicate that these close collisions produce a larger fraction of ions in high charge states than more distant collisions