Differential Diffusion of Helium Isotopes in Glass, Quantum-tunneling 3 He Enrichment, and Portable 3 He/ 4 He Monitoring of Mantle Processes
While studying the scientific and engineering aspects of a field-portable He/ He 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 He enrichment relative to He in lab air, express...
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Published in | Scientific reports Vol. 9; no. 1; p. 5213 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
England
26.03.2019
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Online Access | Get full text |
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Summary: | While studying the scientific and engineering aspects of a field-portable
He/
He 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
He enrichment relative to
He in lab air, expressed as the ratio R and normalized to the accepted
He/
He ratio of 1.40 E-06 (R
), ranges from peak values of about 200 to 600 in dry static samples. Even at the maximum classical
He/
He 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
He 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
He 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
He/
He ratio detectors aimed at earthquake and volcanic eruption studies, and monitoring of nuclear sites. |
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ISSN: | 2045-2322 |