Isotopes of helium

Isotopes of helium (2He)
Main isotopes[1] Decay
abun­dance half-life (t1/2) mode pro­duct
3He 0.0002%
Preview warning: Infobox He isotopes: Abundance percentage not recognised "na=0.0002%" cat#%
 stable
4He 99.9998%
Preview warning: Infobox He isotopes: Abundance percentage not recognised "na=99.9998%" cat#%
 stable
Standard atomic weight Ar°(He)

Helium (2He) (standard atomic weight: 4.002602(2)) has nine known isotopes, but only helium-3 (3He) and helium-4 (4He) are stable.[4] All radioisotopes are short-lived; the longest-lived is 6He with half-life 806.92(24) milliseconds. The least stable is 10He, with half-life 260(40) yoctoseconds (2.6(4)×10−22 s), though 2He may have an even shorter half-life.

In Earth's atmosphere, the ratio of 3He to 4He is 1.343(13)×10−6.[5] However, the isotopic abundance of helium varies greatly depending on its origin. In the Local Interstellar Cloud, the proportion of 3He to 4He is 1.62(29)×10−4,[6] which is ~121 times higher than in Earth's atmosphere. Rocks from Earth's crust have isotope ratios varying by as much as a factor of ten; this is used in geology to investigate the origin of rocks and the composition of the Earth's mantle.[7] The different formation processes of the two stable isotopes of helium produce the differing isotope abundances.

Equal mixtures of liquid 3He and 4He below 0.8 K separate into two immiscible phases due to differences in quantum statistics: 4He atoms are bosons while 3He atoms are fermions.[8] Dilution refrigerators take advantage of the immiscibility of these two isotopes to achieve temperatures of a few millikelvin.

A mix of the two isotopes spontaneously separates into 3He-rich and 4He-rich regions.[9] Phase separation also exists in ultracold gas systems.[10] It has been shown experimentally in a two-component ultracold Fermi gas case.[11][12] The phase separation can compete with other phenomena as vortex lattice formation or an exotic Fulde–Ferrell–Larkin–Ovchinnikov phase.[13]

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  2. ^ "Standard Atomic Weights: Helium". CIAAW. 1983.
  3. ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  4. ^ "helium-3 | chemical isotope | Britannica". www.britannica.com. Retrieved 2022-03-20.
  5. ^ Sano, Yuji; Wakita, Hiroshi; Sheng, Xu (1988). "Atmospheric helium isotope ratio". Geochemical Journal. 22 (4): 177–181. Bibcode:1988GeocJ..22..177S. doi:10.2343/geochemj.22.177. S2CID 129104204.
  6. ^ Busemann, H.; Bühler, F.; Grimberg, A.; Heber, V. S.; Agafonov, Y. N.; Baur, H.; Bochsler, P.; Eismont, N. A.; Wieler, R.; Zastenker, G. N. (2006-03-01). "Interstellar Helium Trapped with the COLLISA Experiment on the MiR Space Station—Improved Isotope Analysis by In Vacuo Etching". The Astrophysical Journal. 639 (1): 246. Bibcode:2006ApJ...639..246B. doi:10.1086/499223. ISSN 0004-637X. S2CID 120648440.
  7. ^ Cite error: The named reference heliumfundamentals was invoked but never defined (see the help page).
  8. ^ The Encyclopedia of the Chemical Elements. p. 264.
  9. ^ Pobell, Frank (2007). Matter and methods at low temperatures (3rd rev. and expanded ed.). Berlin: Springer. ISBN 978-3-540-46356-6. OCLC 122268227.
  10. ^ Carlson, J.; Reddy, Sanjay (2005-08-02). "Asymmetric Two-Component Fermion Systems in Strong Coupling". Physical Review Letters. 95 (6): 060401. arXiv:cond-mat/0503256. Bibcode:2005PhRvL..95f0401C. doi:10.1103/PhysRevLett.95.060401. PMID 16090928. S2CID 448402.
  11. ^ Shin, Y.; Zwierlein, M. W.; Schunck, C. H.; Schirotzek, A.; Ketterle, W. (2006-07-18). "Observation of Phase Separation in a Strongly Interacting Imbalanced Fermi Gas". Physical Review Letters. 97 (3): 030401. arXiv:cond-mat/0606432. Bibcode:2006PhRvL..97c0401S. doi:10.1103/PhysRevLett.97.030401. PMID 16907486. S2CID 11323402.
  12. ^ Zwierlein, Martin W.; Schirotzek, André; Schunck, Christian H.; Ketterle, Wolfgang (2006-01-27). "Fermionic Superfluidity with Imbalanced Spin Populations". Science. 311 (5760): 492–496. arXiv:cond-mat/0511197. Bibcode:2006Sci...311..492Z. doi:10.1126/science.1122318. ISSN 0036-8075. PMID 16373535. S2CID 13801977.
  13. ^ Kopyciński, Jakub; Pudelko, Wojciech R.; Wlazłowski, Gabriel (2021-11-23). "Vortex lattice in spin-imbalanced unitary Fermi gas". Physical Review A. 104 (5): 053322. arXiv:2109.00427. Bibcode:2021PhRvA.104e3322K. doi:10.1103/PhysRevA.104.053322. S2CID 237372963.