نظائر الفلور
قالب:Infobox fluorine isotopes Fluorine (9F) has 18 known isotopes ranging from 13F to 31F (with the exception of 30F) and two isomers (18mF and 26mF). Only fluorine-19 is stable and naturally occurring in more than trace quantities; therefore, fluorine is a monoisotopic and mononuclidic element.
The longest-lived radioisotope is 18F; it has a half-life of 109.734(8) min. All other fluorine isotopes have half-lives of less than a minute, and most of those less than a second. The least stable known isotope is 14F, whose half-life is 500(60) yoctoseconds,[1] corresponding to a resonance width of 910(100) keV.
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قائمة النظائر
| Nuclide[2] [n 1] |
Z | N | Isotopic mass (Da)[3] [n 2][n 3] |
Half-life [n 4] |
Decay mode [n 5] |
Daughter isotope [n 6] |
Spin and parity [n 7][n 4] |
التوافر الطبيعي (mole fraction) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| طاقة الإثارة | Normal proportion | Range of variation | |||||||||||||||||
| 13F[4] | 9 | 4 | 13.045120(540)# | p ?[n 8] | 12O ? | 1/2+# | |||||||||||||
| 14F | 9 | 5 | 14.034320(40) | 500(60) ys [910(100) keV] |
p ?[n 8] | 13O ? | 2− | ||||||||||||
| 15F | 9 | 6 | 15.017785(15) | 1.1(3) zs [376 keV] |
p | 14O | 1/2+ | ||||||||||||
| 16F | 9 | 7 | 16.011460(6) | 21(5) zs [21.3(5.1) keV] |
p | 15O | 0− | ||||||||||||
| 17F[n 9] | 9 | 8 | 17.00209524(27) | 64.370(27) s | β+ | 17O | 5/2+ | ||||||||||||
| 18F[n 10] | 9 | 9 | 18.0009373(5) | 109.734(8) min | β+ | 18O | 1+ | Trace | |||||||||||
| 18mF | 1121.36(15) keV | 162(7) ns | IT | 18F | 5+ | ||||||||||||||
| 19F | 9 | 10 | 18.998403162067(883) | Stable | 1/2+ | 1 | |||||||||||||
| 20F | 9 | 11 | 19.99998125(3) | 11.0062(80) s | β− | 20Ne | 2+ | ||||||||||||
| 21F | 9 | 12 | 20.9999489(19) | 4.158(20) s | β− | 21Ne | 5/2+ | ||||||||||||
| 22F | 9 | 13 | 22.002999(13) | 4.23(4) s | β− (> 89%) | 22Ne | (4+) | ||||||||||||
| β−n (< 11%) | 21Ne | ||||||||||||||||||
| 23F | 9 | 14 | 23.003530(40) | 2.23(14) s | β− (> 86%) | 23Ne | 5/2+ | ||||||||||||
| β−n (< 14%) | 22Ne | ||||||||||||||||||
| 24F | 9 | 15 | 24.008100(100) | 384(16) ms | β− (> 94.1%) | 24Ne | 3+ | ||||||||||||
| β−n (< 5.9%) | 23Ne | ||||||||||||||||||
| 25F | 9 | 16 | 25.012170(100) | 80(9) ms | β− (76.9(4.5)%) | 25Ne | (5/2+) | ||||||||||||
| β−n (23.1(4.5)%) | 24Ne | ||||||||||||||||||
| β−2n ?[n 8] | 23Ne ? | ||||||||||||||||||
| 26F | 9 | 17 | 26.020050(110) | 8.2(9) ms | β− (86.5(4.0)%) | 26Ne | 1+ | ||||||||||||
| β−n (13.5(4.0)%) | 25Ne | ||||||||||||||||||
| β−2n ?[n 8] | 24Ne ? | ||||||||||||||||||
| 26mF | 643.4(1) keV | 2.2(1) ms | IT (82(11)%) | 26F | (4+) | ||||||||||||||
| β−n (12(8)%) | 25Ne | ||||||||||||||||||
| β− ?[n 8] | 26Ne ? | ||||||||||||||||||
| 27F | 9 | 18 | 27.026980(130) | 5.0(2) ms | β−n (77(21)%) | 26Ne | 5/2+# | ||||||||||||
| β− (23(21)%) | 27Ne | ||||||||||||||||||
| β−2n ?[n 8] | 25Ne ? | ||||||||||||||||||
| 28F | 9 | 19 | 28.035860(130) | 46 zs | n | 27F | (4−) | ||||||||||||
| 29F | 9 | 20 | 29.043100(560) | 2.5(3) ms | β−n (60(40)%) | 28Ne | (5/2+) | ||||||||||||
| β− (40(40)%) | 29Ne | ||||||||||||||||||
| β−2n ?[n 8] | 27Ne ? | ||||||||||||||||||
| 31F | 9 | 22 | 31.06020(570)# | 2 ms# [> 260 ns] | β− ?[n 8] | 31Ne ? | 5/2+# | ||||||||||||
| β−n ?[n 8] | 30Ne ? | ||||||||||||||||||
| β−2n ?[n 8] | 29Ne ? | ||||||||||||||||||
| This table header & footer: | |||||||||||||||||||
- ^ mF – Excited nuclear 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).
- ^ أ ب # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
- ^
أنماط الاضمحلال:
EC: Electron capture IT: Isomeric transition n: Neutron emission p: Proton emission - ^ Bold symbol as daughter – Daughter product is stable.
- ^ ( ) spin value – Indicates spin with weak assignment arguments.
- ^ أ ب ت ث ج ح خ د ذ ر Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.
- ^ Intermediate product of various CNO cycles in stellar nucleosynthesis as part of the process producing helium from hydrogen
- ^ Has medicinal uses
Fluorine-18
Of the unstable nuclides of fluorine, 18F has the longest half-life, 109.734(8) min. It decays to 18O via β+ decay. For this reason 18F is a commercially important source of positrons. Its major value is in the production of the radiopharmaceutical fludeoxyglucose, used in positron emission tomography in medicine.
Fluorine-18 is the lightest unstable nuclide with equal odd numbers of protons and neutrons, having 9 of each. (See also the "magic numbers" discussion of nuclide stability.)[5]
Fluorine-19
Fluorine-19 is the only stable isotope of fluorine. Its abundance is 100%; no other isotopes of fluorine exist in significant quantities. Its binding energy is 147801.3648(38) keV. Fluorine-19 is NMR-active with a spin of 1/2+, so it is used in fluorine-19 NMR spectroscopy.
Fluorine-20
Fluorine-20 is an unstable isotope of fluorine. It has a half-life of 11.0062(80) s and decays via beta decay to the stable nuclide 20Ne. Its specific radioactivity is 1.8693(14)×10+21 Bq/g and has a mean lifetime of 15.879(12) s.
Fluorine-21
Fluorine-21, as with fluorine-20, is also an unstable isotope of fluorine. It has a half-life of 4.158(20) s. It undergoes beta decay as well, decaying to 21Ne, which is a stable nuclide. Its specific activity is 4.781(23)×10+21 Bq/g.
Isomers
Only two nuclear isomers (long-lived excited nuclear states), fluorine-18m and fluorine-26m, have been characterized.[1] The half-life of 18mF before it undergoes isomeric transition is 162(7) nanoseconds.[1] This is less than the decay half-life of any of the fluorine radioisotope nuclear ground states except for mass numbers 14–16, 28, and 31. قالب:NUBASE2016 The half-life of 26mF is 2.2(1) milliseconds; it decays mainly to its ground state of 26F or (rarely, via beta-minus decay) to one of high excited states of 26Ne with delayed neutron emission.[1]
وصلات خارجية
المراجع
- ^ أ ب ت ث Kondev, 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.
- ^ Half-life, decay mode, nuclear spin, and isotopic composition is sourced in:
Kondev, 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. - ^ 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.
- ^ Charity, R. J. (2 April 2021). "Observation of the Exotic Isotope 13 F Located Four Neutrons beyond the Proton Drip Line". Physical Review Letters. 126 (13): 2501. Bibcode:2021PhRvL.126m2501C. doi:10.1103/PhysRevLett.126.132501. OSTI 1773500. PMID 33861136. S2CID 233259561. Retrieved 5 April 2021.
- ^ قالب:NNDC
المصادر
- Chisté, V.; Bé, M. M. (2011). Bé, M. M.. ed. 'Table de radionucléides'. CEA (Commissariat à l'énergie atomique et aux énergies alternatives), LIST, LNE-LNHB (Laboratoire National Henri Becquerel/Commissariat à l'Energie Atomique).