Absolute differential and integral cross sections for charge transfer of keV O⁺ ions with O₂

D. R. Sieglaff, B. G. Lindsay, R. L. Merrill, K. A. Smith, and R. F. Stebbings

J. Geophys. Res. 105, 10,631-10,635 (2000)

We report measurements of the absolute differential cross sections for charge-transfer scattering of 0.5-, 0.85-, 1.5-, 2.8-, and 5-keV O⁺ ions by O2 at scattering angles between 0.04° and 5.4° in the laboratory frame. Cross sections for both O⁺(⁴S) ground state and O⁺(²D, ²P) metastable ions are presented. The metastable differential cross section is somewhat more forward peaked than that for the ground state. Integral and total cross sections are also reported. The present O⁺(⁴S) cross section is consistent with previous measurements but the present metastable-state cross section is found to be substantially lower than previously reported in this energy range. These measurements provide information relevant to model calculations of O⁺ precipitation into the upper atmosphere during geomagnetic storms.