Experimental investigation of the asymmetric charge exchange reaction in the Ar +–Ni system in the afterglow of a pulsed glow discharge

Abstract

We have carried out spectroscopic measurements in the afterglow of pulsed glow discharges in Ar and in He–Ar mixtures to investigate elementary processes between Ar + ions and Ni atoms. The emission spectra in the afterglow showed a possibility of asymmetric charge transfer excitation of Ni II levels lying up to 1.6 eV energy difference below the Ar + ion level. For the rate coefficient of this reaction between Ar +( 2P 3/2) ions and Ni atoms we obtained a value k CT = 2.3 (± 0.9) × 10 − 9 cm 3 s − 1 , for room temperature, T = 300 K, conditions. For the reaction involving Ar +( 2P 1/2) ions our measurements made it possible to derive an upper bound of k ⁎ CT ≤ 3.3 (± 1.6) × 10 − 9 cm 3 s − 1 . Via measuring the time-dependence of the intensities of several Ni II spectral lines with different upper level energies we also obtained an upper bound for the rate of the superelastic scattering of electrons with Ar +( 2P 1/2) ions, as k eQ ≤ 1.3 (± 0.8) × 10 − 9 cm 3 s − 1 .