A4 Article in conference proceedings
ESR investigations of spin-pair radicals in nitrogen-helium solids (2006)
Vehmanen, E., Khmelenko, V., Bernard, E., Kunttu, H., & Lee, D. (2006). ESR investigations of spin-pair radicals in nitrogen-helium solids. AIP Conference Proceedings, . https://doi.org/10.1063/1.2354743
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Publication details
All authors or editors: Vehmanen, Esa; Khmelenko, Vladimir; Bernard, Ethan; Kunttu, Henrik; Lee, David
Journal or series: AIP Conference Proceedings
ISSN: 0094-243X
eISSN: 1935-0465
Publication year: 2006
Number in series: 850
Pages range: 374
Publisher: American Institute of Physics
Publication country: United States
Publication language: English
DOI: https://doi.org/10.1063/1.2354743
Publication open access: Not open
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Abstract
We have investigated nitrogen‐helium solids by X‐band CW‐ESR. Our samples, containing molecules and atoms of either the 14N or the 15N isotope, were produced from N2:He gas mixtures with different nitrogen impurity concentrations ranging from 0.25% to 1%. Samples were formed in a helium cryostat at 1.5 K by applying a radio‐frequency discharge to a gas mixture jet that was then introduced into superfluid 4He. We achieved average concentrations of stabilized nitrogen atoms as high as 2⋅1019 atoms/cm3. We observed a strong ESR signal of stabilized nitrogen atoms at ∼3235 Oe. For the first time we also detected weak ESR signals corresponding to the ΔMS = 2 transitions of 14N⋯14N or 15N⋯15N spin‐pair radicals in nitrogen‐helium solids at ∼1617 Oe. The intensities of these signals were ∼1000 or more times smaller than those of the main atomic signals. We investigated the thermal stability of the nitrogen‐helium solids and observed the spin‐pair radical signals in dry samples at T = 3.1 K. After explosive disintegration of the samples at ∼3.3 K, the spin‐pair radical signal disappeared.
Keywords: helium; emission (physics); particulate emissions
Free keywords: Radiofrequency discharges; Thermodynamic states and processes; Superfluids; Explosives; Chemical elements
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