Charge transfer cross sections in collisions of ground state O⁺(⁴S) ions with H₂ and various carbon-containing molecules in the low-energy region

Charge transfer cross sections of the ground state O⁺(⁴S) ions with H₂, CO, CO₂, CH₄, C₂H₂, C₂H₆ and C₃H₈ molecules have been measured using an initial growth rate method in the energy range 0.2-4.5 keV. In the present experiment, the ground state O⁺(⁴S) ions have been produced by carefully energy-controlled electron impact to avoid the influence of the metastable O^+*(²D, ²P) state ions. The observed cross sections are compared with calculations based on a formula developed by Olson. The energy dependence of the present cross sections for H₂ molecules shows a minimum at around 2 keV. The present experimental results for CO and CO₂ molecules are slightly different from previous measurements. For hydrocarbon molecules, where no experimental data are available so far, both the present experimental and calculated results are in good agreement with each other, if product molecular ions are assumed to be in some vibrationally excited states.