Multi-band spectral structure and kinetics of the third continua in Ar, Kr and Xe gases excited by a pulsed discharge
Institute of Physics, University of Tartu, Riia 142, 51014 Tartu, Estonia
Received: 15 November 2011
Received in final form: 23 February 2012
Published online: 19 April 2012
Time-resolved VUV-UV emission of Ar, Kr, and Xe gases (Rg), excited by a pulsed discharge, have been measured to clarify the origin of the 3rd continua. Several detected continuum bands exhibit very different time behaviors due to various atomic (ionic) precursors and plasma kinetics. Imaging experiments with ns-gated ICCD camera have shown that the 2nd continua (Rg2∗) and Rg∗ lines emit uniformly in the positive column of the discharge. However, the 3rd continua and Rg+∗ lines were excited exclusively in the negative glow zone, where high-energy electrons are injected from the cathode layer. The multi-band structure of the 3rd continua has been connected with Rg2+ ions produced in the ground and different excited states. These precursors lead to the formation of several bound states Rg22+∗, which decay radiatively to the repulsive states (Rg + + Rg+), where Rg+ ions can be on 2P3/2, 2P1/2 levels due to spin-orbit coupling. The rate constants for the formation of Rg22+ excimers in three-body reaction and two-body collisional quenching of Rg2+∗ ions have been determined from the time behaviors of emission. The quenching of Rg2+∗ ions is explained by the level crossing between bound (Rg2+∗ + Rg) and repulsive (Rg2 + + Rg) potential curves.
Key words: Plasma Physics
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2012