Dissociation of O-2 in low pressure glow discharges in He-O-2, Ne-O-2, and Ar-O-2 gas mixtures

作者：Khan Mohammad Aslam^*; Al Jalal Abdulaziz M

来源：Journal of Applied Physics, 2008, 104(12): 123302.

DOI：10.1063/1.3043886

Low-pressure glow discharges in He, Ne, or Ar gases containing small amounts of O-2 can produce considerable dissociation of O-2 molecules. High-lying metastable states in these noble gases play a predominant role in this process. Due to the difference in energies of metastable states of the noble gas atoms, there is a significant variation in the product states of O atoms created as a result of dissociation. Apparently, for He and Ne, superexcited O-2 molecules are formed through collisions with high-lying metastable states of the noble gases. The superexcited O-2 molecule could either autoionize to form an O2+ ion that subsequently captures an electron and dissociates or it could directly dissociate through some curve-crossing interactions yielding at least one atom in highly excited state. However, in the case of Ar, the formation of superexcited O-2 may be possible through a prior creation of Ar-2(+) ion. We report some interesting observations on spectral emissions from O atoms in the three gas mixtures covering transition from 5d, 4d D-3,D-5, and 5s S-3,S-5, to 3p P-3,P-5 levels and 4p and 3p P-3,P-5 to 3s S-3,S-5 levels. The emission from the b (4)Sigma g (-)(g)- a (4 Sigma)Pi(u) system of O-2(+) ions is also reported. In general, populations of the above-stated O and O-2(+) levels are highest in the case of He-O-2 mixture and lowest for the Ar-O-2 mixture. However, the Ne-O-2 mixture appears to strongly populate the 4p P-5 levels, while the Ar-O-2 mixture strongly populates the 3p P-3 levels. The He-O-2 mixture appears to be more efficient among the three gas mixtures considered in dissociating the O-2 molecules.

• 出版日期2008-12-15
• 单位中国石油大学（北京）