Physics:Isotopes of beryllium

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Short description: Nuclides with atomic number of 4 but with different mass numbers
Main isotopes of Chemistry:beryllium (4Be)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
7Be trace 53.12 d ε 7Li
γ –
9Be 100% stable
10Be trace 1.39×106 y β− 10B
Standard atomic weight Ar, standard(Be)
  • 9.0121831(5)[1]
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Beryllium (4Be) has 11 known isotopes and 3 known isomers, but only one of these isotopes (9Be) is stable and a primordial nuclide. As such, beryllium is considered a monoisotopic element. It is also a mononuclidic element, because its other isotopes have such short half-lives that none are primordial and their abundance is very low (standard atomic weight is 9.0121831(5)). Beryllium is unique as being the only monoisotopic element with both an even number of protons and an odd number of neutrons. There are 25 other monoisotopic elements but all have odd atomic numbers, and even numbers of neutrons.

Of the 10 radioisotopes of beryllium, the most stable are 10Be with a half-life of 1.387(12) million years[nb 1] and 7Be with a half-life of 53.22(6) d. All other radioisotopes have half-lives under 15 s, most under 30 milliseconds. The least stable isotope is 16Be, with a half-life of 650(130) yoctoseconds.

The 1:1 neutron–proton ratio seen in stable isotopes of many light elements (up to oxygen, and in elements with even atomic number up to calcium) is prevented in beryllium by the extreme instability of 8Be toward alpha decay, which is favored due to the extremely tight binding of 4He nuclei. The half-life for the decay of 8Be is only 81.9(3.7) attoseconds.

Beryllium is prevented from having a stable isotope with 4 protons and 6 neutrons by the very large mismatch in neutron–proton ratio for such a light element. Nevertheless, this isotope, 10Be, has a half-life of 1.387(12) million years[nb 1], which indicates unusual stability for a light isotope with such a large neutron/proton imbalance. Other possible beryllium isotopes have even more severe mismatches in neutron and proton number, and thus are even less stable.

Most 9Be in the universe is thought to be formed by cosmic ray nucleosynthesis from cosmic ray spallation in the period between the Big Bang and the formation of the Solar System. The isotopes 7Be, with a half-life of 53.22(6) d, and 10Be are both cosmogenic nuclides because they are made on a recent timescale in the Solar System by spallation,[2] like 14C.

List of isotopes

Nuclide
[n 1] 		Z N Isotopic mass (u)
[n 2][n 3] 		Half-life

[resonance width] 		Decay
mode
[n 4] 		Daughter
isotope
[n 5] 		Spin and
parity
[n 6] 		Physics:Natural abundance (mole fraction)
Excitation energy Normal proportion Range of variation
5Be[n 7] 4 1 5.03987(215)# p ?[n 8] 4Li ? (1/2+)#
6Be 4 2 6.019726(6) 5.0(3) zs
[91.6(5.6) keV] 		2p 4He 0+
7Be[n 9] 4 3 7.01692871(8) 53.22(6) d ε 7Li 3/2− Trace[n 10]
8Be[n 11] 4 4 8.00530510(4) 81.9(3.7) as
[5.58(25) eV] 		α [n 12] 4He 0+
8mBe 16626(3) keV α 4He 2+
9Be 4 5 9.01218306(8) Stable 3/2− 1
9mBe 14390.3(1.7) keV 1.25(10) as
[367(30) eV] 		3/2−
10Be 4 6 10.01353469(9) 1.387(12)×106 y[nb 1] β− 10B 0+ Trace[n 10]
11Be[n 13] 4 7 11.02166108(26) 13.76(7) s β− (96.7(1)%) 11B 1/2+
β−α (3.3(1)%) 7Li
β−p (0.0013(3)%) 10Be
11mBe 21158(20) keV 0.93(13) zs
[500(75) keV] 		IT ?[n 8] 11Be ? 3/2−
12Be 4 8 12.0269221(20) 21.46(5) ms β− (99.50(3)%) 12B 0+
β−n (0.50(3)%) 11B
12mBe 2251(1) keV 233(7) ns IT 12Be 0+
13Be 4 9 13.036135(11) 1.0(7) zs n ?[n 8] 12Be ? (1/2−)
13mBe 1500(50) keV (5/2+)
14Be[n 14] 4 10 14.04289(14) 4.53(27) ms β−n (86(6)%) 13B 0+
β− (> 9.0(6.3)%) 14B
β−2n (5(2)%) 12B
β−t (0.02(1)%) 11Be
β−α (< 0.004%) 10Li
14mBe 1520(150) keV (2+)
15Be 4 11 15.05349(18) 790(270) ys n 14Be (5/2+)
16Be 4 12 16.06167(18) 650(130) ys
[0.73(18) MeV] 		2n 14Be 0+
  1. ↑ mBe – Excited nuclear isomer.
  2. ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. ↑ Modes of decay:
    EC: Electron capture
    IT: Isomeric transition
    n: Neutron emission
    p: Proton emission
  5. ↑ Bold symbol as daughter – Daughter product is stable.
  6. ↑ ( ) spin value – Indicates spin with weak assignment arguments.
  7. ↑ This isotope has not yet been observed; given data is inferred or estimated from periodic trends.
  8. ↑ 8.0 8.1 8.2 Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.
  9. ↑ Produced in Big Bang nucleosynthesis, but not primordial, as it all quickly decayed to 7Li
  10. ↑ 10.0 10.1 cosmogenic nuclide
  11. ↑ Intermediate product of triple alpha process in stellar nucleosynthesis as part of the path producing 12C
  12. ↑ Also often considered spontaneous fission, as 8Be splits into two equal 4He nuclei
  13. ↑ Has 1 halo neutron
  14. ↑ Has 4 halo neutrons

Beryllium-7

Beryllium-7 is an isotope with a half-life of 53.3 days that is generated naturally as a cosmogenic nuclide.[2] The rate at which the short-lived 7Be is transferred from the air to the ground is controlled in part by the weather. 7Be decay in the Sun is one of the sources of solar neutrinos, and the first type ever detected using the Homestake experiment. Presence of 7Be in sediments is often used to establish that they are fresh, i.e. less than about 3–4 months in age, or about two half-lives of 7Be.[3]

The rate of delivery of 7Be from the air to the ground in Japan[3]

Beryllium-10

Main page: Physics:Beryllium-10
Plot showing variations in solar activity, including variation in 10Be concentration which varies inversely with solar activity. (Note that the beryllium scale is inverted, so increases on this scale indicate lower beryllium-10 levels).

Beryllium-10 has a half-life of 1.39×106 y, and decays by beta decay to stable boron-10 with a maximum energy of 556.2 keV.[4][5] It is formed in the Earth's atmosphere mainly by cosmic ray spallation of nitrogen and oxygen.[6][7][8] 10Be and its daughter product have been used to examine soil erosion, soil formation from regolith, the development of lateritic soils and the age of ice cores.[9] 10Be is a significant isotope used as a proxy data measure for cosmogenic nuclides to characterize solar and extra-solar attributes of the past from terrestrial samples.[10]

Decay chains

Most isotopes of beryllium within the proton/neutron drip lines decay via beta decay and/or a combination of beta decay and alpha decay or neutron emission. However, 7Be decays only via electron capture, a phenomenon to which its unusually long half-life may be attributed. Notably, its half-life can be artificially lowered by 0.83% via endohedral enclosure (7Be@C60).[11] Also anomalous is 8Be, which decays via alpha decay to 4He. This alpha decay is often considered fission, which would be able to account for its extremely short half-life.

[math]\displaystyle{ \begin{array}{l}{}\\ \ce{^5_4Be -\gt [\ce{Unknown}] {^4_3Li} + {^1_1H}} \\ \ce{^6_4Be -\gt [5 \ \ce{zs}] {^4_2He} + {2^1_1H}} \\ \ce{{^7_4Be} + e^- -\gt [53.22 \ \ce{d}] {^7_3Li}} \\ \ce{^8_4Be -\gt [81.9 \ \ce{as}] {2^4_2He}} \\ \ce{^{10}_4Be -\gt [1.387 \ \ce{Ma}] {^{10}_5B} + e^-} \\ \ce{^{11}_4Be -\gt [13.76 \ \ce{s}] {^{11}_5B} + e^-} \\ \ce{^{11}_4Be -\gt [13.76 \ \ce{s}] {^7_3Li} + {^4_2He} + e^-} \\ \ce{^{12}_4Be -\gt [21.46 \ \ce{ms}] {^{12}_5B} + e^-} \\ \ce{^{12}_4Be -\gt [21.46 \ \ce{ms}] {^{11}_5B} + {^1_0n} + e^-} \\ \ce{^{13}_4Be -\gt [1 \ \ce{zs}] {^{12}_4Be} + {^1_0n}} \\ \ce{^{14}_4Be -\gt [4.53 \ \ce{ms}] {^{13}_5B} + {^1_0n} + e^-} \\ \ce{^{14}_4Be -\gt [4.53 \ \ce{ms}] {^{14}_5B} + e^-} \\ \ce{^{14}_4Be -\gt [4.53 \ \ce{ms}] {^{12}_5B} + {2^1_0n} + e^-} \\ \ce{^{15}_4Be -\gt [790 \ \ce{ys}] {^{14}_4Be} + {^1_0n}} \\{} \ce{^{16}_4Be -\gt [650 \ \ce{ys}] {^{14}_4Be} + {2^1_0n}} \\{} \end{array} }[/math]

Notes

  1. ↑ 1.0 1.1 1.2 Note that NUBASE2020 uses the tropical year to convert between years and other units of time, not the Gregorian year. The relationship between years and other time units in NUBASE2020 is as follows: 1 y = 365.2422 d = 31 556 926 s

References

  1. ↑ Meija, Juris; Coplen, Tyler B.; Berglund, Michael; Brand, Willi A.; De Bièvre, Paul; Gröning, Manfred; Holden, Norman E.; Irrgeher, Johanna et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry 88 (3): 265–91. doi:10.1515/pac-2015-0305. 
  2. ↑ 2.0 2.1 Mishra, Ritesh Kumar; Marhas, Kuljeet Kaur (2019-03-25). "Meteoritic evidence of a late superflare as source of 7 Be in the early Solar System" (in en). Nature Astronomy 3 (6): 498–505. doi:10.1038/s41550-019-0716-0. ISSN 2397-3366. Bibcode: 2019NatAs...3..498M. 
  3. ↑ 3.0 3.1 Yamamoto, Masayoshi; Sakaguchi, Aya; Sasaki, Keiichi; Hirose, Katsumi; Igarashi, Yasuhito; Kim, Chang Kyu (January 2006). "Seasonal and spatial variation of atmospheric 210Pb and 7Be deposition: features of the Japan Sea side of Japan". Journal of Environmental Radioactivity 86 (1): 110–131. doi:10.1016/j.jenvrad.2005.08.001. PMID 16181712. 
  4. ↑ G. Korschinek; A. Bergmaier; T. Faestermann; U. C. Gerstmann (2010). "A new value for the half-life of 10Be by Heavy-Ion Elastic Recoil Detection and liquid scintillation counting". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 268 (2): 187–191. doi:10.1016/j.nimb.2009.09.020. Bibcode: 2010NIMPB.268..187K. 
  5. ↑ J. Chmeleff; F. von Blanckenburg; K. Kossert; D. Jakob (2010). "Determination of the 10Be half-life by multicollector ICP-MS and liquid scintillation counting". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 268 (2): 192–199. doi:10.1016/j.nimb.2009.09.012. Bibcode: 2010NIMPB.268..192C. http://gfzpublic.gfz-potsdam.de/pubman/item/escidoc:239521. 
  6. ↑ G.A. Kovaltsov; I.G. Usoskin (2010). "A new 3D numerical model of cosmogenic nuclide 10Be production in the atmosphere". Earth Planet. Sci. Lett. 291 (1–4): 182–199. doi:10.1016/j.epsl.2010.01.011. Bibcode: 2010E&PSL.291..182K. 
  7. ↑ J. Beer; K. McCracken; R. von Steiger (2012). Cosmogenic radionuclides: theory and applications in the terrestrial and space environments. Physics of Earth and Space Environments. 26. Physics of Earth and Space Environments, Springer, Berlin. doi:10.1007/978-3-642-14651-0. ISBN 978-3-642-14650-3. 
  8. ↑ S.V. Poluianov; G.A. Kovaltsov; A.L. Mishev; I.G. Usoskin (2016). "Production of cosmogenic isotopes 7Be, 10Be, 14C, 22Na, and 36Cl in the atmosphere: Altitudinal profiles of yield functions". J. Geophys. Res. Atmos. 121 (13): 8125–8136. doi:10.1002/2016JD025034. Bibcode: 2016JGRD..121.8125P. 
  9. ↑ Balco, Greg; Shuster, David L. (2009). "26Al-10Be–21Ne burial dating". Earth and Planetary Science Letters 286 (3–4): 570–575. doi:10.1016/j.epsl.2009.07.025. Bibcode: 2009E&PSL.286..570B. http://www.bgc.org/shuster/BalcoShuster(2009b)_Al_Be_Ne_burial_dating.pdf. Retrieved 2012-12-10. 
  10. ↑ Paleari, Chiara I.; F. Mekhaldi; F. Adolphi; M. Christl; C. Vockenhuber; P. Gautschi; J. Beer; N. Brehm et al. (2022). "Cosmogenic radionuclides reveal an extreme solar particle storm near a solar minimum 9125 years BP". Nat. Commun. 13 (214): 214. doi:10.1038/s41467-021-27891-4. PMID 35017519. Bibcode: 2022NatCo..13..214P. 
  11. ↑ Ohtsuki, T.; Yuki, H.; Muto, M.; Kasagi, J.; Ohno, K. (9 September 2004). "Enhanced Electron-Capture Decay Rate of 7Be Encapsulated in C60 Cages". Physical Review Letters 93 (11): 112501. doi:10.1103/PhysRevLett.93.112501. PMID 15447332. Bibcode: 2004PhRvL..93k2501O. https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.93.112501. Retrieved 23 February 2022. 



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