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We studied luminescence accompanied by an injection of nitrogen–krypton–helium gas mixtures after passing radiofrequency discharge into dense cold helium gas. In the cold helium gas N2–Kr nanoclusters were formed, with a core of Kr atoms and N2 molecules on the surface. Atomic nitrogen and oxygen resided in the N2 surface layers. When the temperature in the observation zone was in the range of 20–36 K, we observed enhanced emission of oxygen atom β-group and molecular nitrogen Vegard–Kaplan bands from N2–Kr nanoclusters. At these temperatures, nitrogen atoms efficiently recombine on the surface of nanoclusters with the formation of exited nitrogen molecules, leading to enhanced emission of Vegard–Kaplan bands. Simultaneously, the energy transfer from exited nitrogen molecules to the oxygen atoms enhanced O atom β-group emission.
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Photoionization of air species as impurities in atmospheric pressure helium plasma
Abstract We revisit the problem of photoionization of small admixtures of nitrogen and oxygen molecules in atmospheric pressure helium plasma originally formulated in the pioneering work of Naidis (2010J. Phys. D: Appl. Phys.43402001). The radiation trapping of resonance emission lines in atomic helium is quantified, and it is demonstrated that photoionization occurs due to radiative decay of the electronicAstate of helium molecules. The collisions and atomic precursors that populate the excitedAstate of the helium molecule are clearly identified. The Einstein probabilities for the transition from bound and quasi-bound rovibrational levels of theAstate to the continuum of the groundXstate are provided. A kinetic scheme for the production of the fast component of ultraviolet emissions in atmospheric pressure helium plasma is proposed. The photoionization of molecular oxygen and molecular nitrogen as impurities in 99.9% and 99.99% purity helium is studied.
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- Award ID(s):
- 2010088
- PAR ID:
- 10463858
- Publisher / Repository:
- IOP Publishing
- Date Published:
- Journal Name:
- Plasma Sources Science and Technology
- Volume:
- 32
- Issue:
- 9
- ISSN:
- 0963-0252
- Page Range / eLocation ID:
- Article No. 095011
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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