Formation of O−2 in charge transfer collisions of fast molecular hydrogen ions with O2 molecules

Abstract

Abstract.Cross sections for the production of O2-in charge transfer collisions of fast molecular hydrogen ions (Hf, Dr, Hf, and Df of 10 to 140 keV kinetic energy) with 02 molecules have been determined by means of a time-of-flight mass spectrometer analysing the slow negative product ions from the collisions. Within the measuring accuracy equivelocity Hf and Df ions have the same cross sections for the generation of Of. The projectile velocity dependence curve of the cross section passes through a broad maximum with a peak value of about 6.5 x 10 -is cm 2 around the Bohr velocity (25 keV/u) before showing an asymptotic decrease still within the limited energy range under investigation that is in inverse proportion to the square of velocity. Throughout the examined energy range H + ions yield a cross section which is about 1.4 times larger than that of Hf ions of the same velocity. The fragment ion O-has been found to appear with cross sections between 10 -19 and 10 -28 cm 2 upon collisional excitation in the energy range under investigation, with ever decreasing intensity when the energy of the positive hydrogen ions, the proton included, was increased.