Differential Diffusion of Helium Isotopes in Glass, Quantum-tunneling 3He Enrichment, and Portable 3He/4He Monitoring of Mantle Processes

Autor: James Robert DeLuze, Gary M. McMurtry, David R. Hilton, James E. Blessing
Jazyk: angličtina
Rok vydání: 2019
Předmět:
Zdroj: Scientific Reports, Vol 9, Iss 1, Pp 1-8 (2019)
ISSN: 2045-2322
Popis: While studying the scientific and engineering aspects of a field-portable 3He/4He ratio detector, we found elevated ratios at comparatively lower temperatures that appear to result from differential diffusion of these isotopes in pure quartz glass. The 3He enrichment relative to 4He in lab air, expressed as the ratio R and normalized to the accepted 3He/4He ratio of 1.40 E-06 (Ra), ranges from peak values of about 200 to 600 in dry static samples. Even at the maximum classical 3He/4He diffusivity ratio of 1.15, the expected R would be only 1.61 E-06. Within a narrow temperature window, the air value in our experimental set up with pure quartz glass can range from about 2.70 to 8.20 E-04, or nearly 1000 times the expected enrichment based upon classical fractionation. When plotted versus temperature, the narrow 3He net partial pressure peak reveals at least three sharper embedded peaks that may be quantized vibrational entrance states in quartz glass which are temperature specific. This discovery has implications for relatively low-energy industrial enrichment of scarce 3He from natural sources on Earth, and for radiogenic and cosmogenic helium dating assumptions in natural glasses. It also has bearing upon designs for field portable 3He/4He ratio detectors aimed at earthquake and volcanic eruption studies, and monitoring of nuclear sites.
Databáze: OpenAIRE
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