VUV Emission and Energy Transfer Phenomena in Rare Gas Mixture Discharges

Abstract: VUV emission spectra of Xe-X (X = He, Ne, Ar and Kr) and of Kr-Y (Y = He, Ne and Ar) mixtures with low concentrations of the heavier gases (0.1 - 1 %) and moderate total pressures (50 - 200 hPa) are recorded near each of the two resonance lines of Xe and Kr in DC glow capillary discharges. A tentative identification of the emission structures is given.Numerical simulations of absorption spectra from Kr-Xe mixtures close to the Xe resonance line at 146.96 nm are performed. It is shown that the absorption structures can result from bound-bound and bound-free transitions in XeKr molecules between the ground state and the weakly-bound 1(3P1) excited state. The depth of the excited state is estimated.Simultaneous observations of the VUV and visible - near IR emission from DC and RF discharges in gaseous Kr with small Xe admixture concentrations are conducted. A scheme of energy transfer processes in Kr-Xe mixtures is proposed. The emission spectra are used for investigation of energy transfer from the lowest excited states of both atomic krypton and krypton molecules to the ground state xenon atoms. Values of energy transfer rates from the 1u state of Kr2' molecules and from the system of the four lowest Kr excited states to Xe ground state atoms are obtained.Energy transfer processes in gaseous Ar with a small admixture of N2 excited in a transverse pulse discharge are investigated and an energy transfer scheme is proposed. The results confirm that all emitting species have Ar metastable state 3P2 as their common source of excitation energy. Evidences of strong energy transfer from Ar2'(1u) molecules and the reabsorbed Ar state 3P1 to atomic nitrogen are also obtained.