Dissociative Recombination of \({\text{Ne}}_{{\text{2}}}^{ + }\) Molecular Ions with Electrons: Population of Ne(2р54р) Atoms in a Decaying Plasma

Abstract

Decaying neon plasma has been investigated by kinetic spectroscopy. The experimental conditions were neon pressure of 0.2–152 Torr and electron density in the initial stage of decay [e] ≤ 5 × 10¹⁰ cm^–3. The plasma was created by a pulsed barrier discharge with electrodes on the outer surface of a cylindrical glass tube. The discharge frequency was 40–160 Hz. It has been shown based on a comparative analysis of the dependences of the intensities of spectral lines on the time and electron temperature in the afterglow that the 2р⁵4р levels are clearly divided into two groups in terms of population mechanisms. The lower levels (from 3р₁₀ to 3р₃ (Paschen notations)) are related to dissociative recombination of \({\text{Ne}}_{{\text{2}}}^{ + }\) molecular ions with electrons, and the lines emitted by them behaved identically to the lines of the transitions 2p⁵3s ← 2p⁵3p and 2p⁵3p ← 2p⁵3d up to pressures of 0.6 Torr. The kinetics of the upper levels (3р₅, 3р₂, 3р₄, and 3р₁) had a more complicated character, and, at low pressures, the populations of all 2p⁵4p levels were related to a collisional-radiative recombination of Ne⁺ ions. Significant differences in the dependences of the relative populations of 3d- and 4p levels on neon pressure are discussed.