Negatively and positively charged oxygen ion formation in collisions of positively charged projectiles with O molecules in the energy range 50–350 keV

Abstract

Absolute cross sections for positive and negative ion fragments formed from O2 molecules following collisions with H+, H2+, He+, and Ar+ projectiles in the energy range 50–350 keV are presented. Cross sections for negatively charged secondary ions are much smaller ( cm2) compared to those for positively charged fragments. The non-dissociative formation of negatively charged O2− ions results from an electron transfer collision with the projectile. The impact energy dependence shows that the collision cross section for O2− formation strongly depends on the type of projectile involved.