Low energy ion-neutral reactions, 4

Cross sections for formation of NO + and N 2 + in O + +N 2 collisions are measured by the injected-ion drift tube technique from 0.04 eV to 3 eV in the center of mass system. The cross section curve obtained for N 2 + formation is used to determine the fractional density of the excited state ions in the primary O + beam. The cross section for NO + formation by O + (4 S) has a minimum at 0.12 eV, and increases rapidly with the collision energy. The minimum value is determined as 9×10 -18 cm 2 with 50% accuracy. The results obtained are compared with the previous works. The cross section for NO + formation by O + (2 D) at the same energy is tentatively determined as 1.2×10 -16 cm 2, and it can be larger if the collisional deexcitation of the 2 D state, possible in the drift tube, has to be taken into account. These results may be useful for the ionospheric research.