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Boron (5B) naturally occurs asisotopes10
B
and11
B
, the latter of which makes up about 80% of natural boron. There are 13radioisotopes that have been discovered, with mass numbers from 7 to 21, all with shorthalf-lives, the longest being that of8
B
, with a half-life of only771.9(9) ms and12
B
with a half-life of20.20(2) ms. All other isotopes have half-lives shorter than17.35 ms. Those isotopes with mass below 10 decay intohelium (via short-livedisotopes of beryllium for7
B
and9
B
) while those with mass above 11 mostly becomecarbon.
| ||||||||||||||||||||||||||
| Standard atomic weightAr°(B) | ||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
List of isotopes
edit| Nuclide [n 1] | Z | N | Isotopic mass(Da)[3] [n 2][n 3] | Half-life[4] [resonance width] | Decay mode[4] [n 4] | Daughter isotope [n 5] | Spin and parity[4] [n 6][n 7] | Natural abundance(mole fraction) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Excitation energy | Normal proportion[4] | Range of variation | |||||||||||||||||
| 6 B ?[n 8] | 5 | 1 | 6.050800(2150) | p-unstable | 2p? | 4 Li ? | 2−# | ||||||||||||
| 7 B | 5 | 2 | 7.029712(27) | 570(14) ys [801(20) keV] | p | 6 Be [n 9] | (3/2−) | ||||||||||||
| 8 B [n 10][n 11] | 5 | 3 | 8.0246073(11) | 771.9(9) ms | β+α | 4 He | 2+ | ||||||||||||
| 8m B | 10624(8) keV | 0+ | |||||||||||||||||
| 9 B | 5 | 4 | 9.0133296(10) | 800(300) zs | p | 8 Be [n 12] | 3/2− | ||||||||||||
| 10 B [n 13] | 5 | 5 | 10.012936862(16) | Stable | 3+ | [0.189,0.204][5] | |||||||||||||
| 11 B | 5 | 6 | 11.009305167(13) | Stable | 3/2− | [0.796,0.811][5] | |||||||||||||
| 11m B | 12560(9) keV | 1/2+, (3/2+) | |||||||||||||||||
| 12 B | 5 | 7 | 12.0143526(14) | 20.20(2) ms | β− (99.40(2)%) | 12 C | 1+ | ||||||||||||
| β−α (0.60(2)%) | 8 Be [n 14] | ||||||||||||||||||
| 13 B | 5 | 8 | 13.0177800(11) | 17.16(18) ms | β− (99.734(36)%) | 13 C | 3/2− | ||||||||||||
| β−n (0.266(36)%) | 12 C | ||||||||||||||||||
| 14 B | 5 | 9 | 14.025404(23) | 12.36(29) ms | β− (93.96(23)%) | 14 C | 2− | ||||||||||||
| β−n (6.04(23)%) | 13 C | ||||||||||||||||||
| β−2n ?[n 15] | 12 C ? | ||||||||||||||||||
| 14m B | 17065(29) keV | 4.15(1.90) zs | IT ?[n 15] | 0+ | |||||||||||||||
| 15 B | 5 | 10 | 15.031087(23) | 10.18(35) ms | β−n (98.7(1.0)%) | 14 C | 3/2− | ||||||||||||
| β− (<1.3%) | 15 C | ||||||||||||||||||
| β−2n (<1.5%) | 13 C | ||||||||||||||||||
| 16 B | 5 | 11 | 16.039841(26) | >4.6 zs | n ?[n 15] | 15 B ? | 0− | ||||||||||||
| 17 B [n 16] | 5 | 12 | 17.04693(22) | 5.08(5) ms | β−n (63(1)%) | 16 C | (3/2−) | ||||||||||||
| β− (21.1(2.4)%) | 17 C | ||||||||||||||||||
| β−2n (12(2)%) | 15 C | ||||||||||||||||||
| β−3n (3.5(7)%) | 14 C | ||||||||||||||||||
| β−4n (0.4(3)%) | 13 C | ||||||||||||||||||
| 18 B | 5 | 13 | 18.05560(22) | <26 ns | n | 17 B | (2−) | ||||||||||||
| 19 B [n 17] | 5 | 14 | 19.06417(56) | 2.92(13) ms | β−n (71(9)%) | 18 C | (3/2−) | ||||||||||||
| β−2n (17(5)%) | 17 C | ||||||||||||||||||
| β−3n (<9.1%) | 16 C | ||||||||||||||||||
| β− (>2.9%) | 19 C | ||||||||||||||||||
| 20 B [6] | 5 | 15 | 20.07451(59) | >912.4 ys | n | 19 B | (1−, 2−) | ||||||||||||
| 21 B [6] | 5 | 16 | 21.08415(60) | >760 ys | 2n | 19 B | (3/2−) | ||||||||||||
| This table header & footer: | |||||||||||||||||||
- ^mB – Excitednuclear isomer.
- ^( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
- ^# – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
- ^Modes of decay:
n: Neutron emission p: Proton emission - ^Bold symbol as daughter – Daughter product is stable.
- ^( ) spin value – Indicates spin with weak assignment arguments.
- ^# – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
- ^This isotope has not yet been observed; given data is inferred or estimated from periodic trends.
- ^Subsequently decays by double proton emission to4
He
for a net reaction of7
B
→4
He
+ 3 1
H - ^Has 1halo proton
- ^Intermediate product ofa branch of proton-proton chain in stellar nucleosynthesis as part of the process converting hydrogen to helium
- ^Immediately decays into two α particles, for a net reaction of9
B
→ 2 4
He
+1
H - ^One of the few stableodd-odd nuclei
- ^Immediately decays into two α particles, for a net reaction of12
B
→ 3 4
He
+ e− - ^abcDecay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.
- ^Has 2 halo neutrons
- ^Has 4 halo neutrons
Boron-8
editBoron-8 is an isotope of boron that undergoes β+ decay toberyllium-8 with a half-life of771.9(9) ms. It is the strongest candidate for ahalo nucleus with a loosely-bound proton, in contrast to neutron halo nuclei such aslithium-11.[7]
Although boron-8 beta decayneutrinos from the Sun make up only about 80 ppm of the totalsolar neutrino flux, they have a higher energy centered around 10 MeV,[8] and are an important background to dark matterdirect detection experiments.[9] They are the first component of the neutrino floor that dark matter direct detection experiments are expected to eventually encounter.
Applications
editBoron-10
editBoron-10 is used inboron neutron capture therapy as an experimental treatment of some brain cancers.
References
edit- ^"Standard Atomic Weights: Boron".CIAAW. 2009.
- ^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.
- ^Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*".Chinese Physics C.45 (3): 030003.doi:10.1088/1674-1137/abddaf.
- ^abcdKondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021)."The NUBASE2020 evaluation of nuclear properties"(PDF).Chinese Physics C.45 (3): 030001.doi:10.1088/1674-1137/abddae.
- ^ab"Atomic Weight of Boron".CIAAW.
- ^abLeblond, S.; et al. (2018). "First observation of20B and21B".Physical Review Letters.121 (26): 262502–1–262502–6.arXiv:1901.00455.doi:10.1103/PhysRevLett.121.262502.PMID 30636115.S2CID 58602601.
- ^Maaß, Bernhard; Müller, Peter; Nörtershäuser, Wilfried; Clark, Jason; Gorges, Christian; Kaufmann, Simon; König, Kristian; Krämer, Jörg; Levand, Anthony; Orford, Rodney; Sánchez, Rodolfo; Savard, Guy; Sommer, Felix (November 2017). "Towards laser spectroscopy of the proton-halo candidate boron-8".Hyperfine Interactions.238 (1): 25.Bibcode:2017HyInt.238...25M.doi:10.1007/s10751-017-1399-5.S2CID 254551036.
- ^Bellerive, A. (2004). "Review of solar neutrino experiments".International Journal of Modern Physics A.19 (8):1167–1179.arXiv:hep-ex/0312045.Bibcode:2004IJMPA..19.1167B.doi:10.1142/S0217751X04019093.S2CID 16980300.
- ^Cerdeno, David G.; Fairbairn, Malcolm; Jubb, Thomas; Machado, Pedro; Vincent, Aaron C.; Boehm, Celine (2016). "Physics from solar neutrinos in dark matter direct detection experiments".JHEP.2016 (5): 118.arXiv:1604.01025.Bibcode:2016JHEP...05..118C.doi:10.1007/JHEP05(2016)118.S2CID 55112052.