Fluorine (9F) has 18 known isotopes ranging from 13
F
to 31
F
(with the exception of 30
F
) and two isomers (18m
F
and 26m
F
). Only fluorine-19 is stable and naturally occurring in more than trace quantities; therefore, fluorine is a monoisotopic and mononuclidic element.
| |||||||||||||||||||||
| Standard atomic weight Ar°(F) | |||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
The longest-lived radioisotope is 18
F
; 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 14
F
, whose half-life is 500(60) yoctoseconds,[4] corresponding to a resonance width of 910(100) keV.
List of isotopes
| Nuclide [n 1] | Z | N | Isotopic mass (Da)[5] [n 2][n 3] | Half-life[4] [n 4] | Decay mode[4] [n 5] | Daughter isotope [n 6] | Spin and parity[4] [n 7][n 4] | Isotopic abundance | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Excitation energy | |||||||||||||||||||
| 13 F [6] | 9 | 4 | 13.045120(540)# | p ?[n 8] | 12 O ? | 1/2+# | |||||||||||||
| 14 F | 9 | 5 | 14.034320(40) | 500(60) ys [910(100) keV] | p ?[n 8] | 13 O ? | 2− | ||||||||||||
| 15 F | 9 | 6 | 15.017785(15) | 1.1(3) zs [376 keV] | p | 14 O | 1/2+ | ||||||||||||
| 16 F | 9 | 7 | 16.011460(6) | 21(5) zs [21.3(5.1) keV] | p | 15 O | 0− | ||||||||||||
| 17 F [n 9] | 9 | 8 | 17.00209524(27) | 64.370(27) s | β+ | 17 O | 5/2+ | ||||||||||||
| 18 F [n 10] | 9 | 9 | 18.0009373(5) | 109.734(8) min | β+ | 18 O | 1+ | Trace | |||||||||||
| 18m F | 1121.36(15) keV | 162(7) ns | IT | 18 F | 5+ | ||||||||||||||
| 19 F | 9 | 10 | 18.998403162067(883) | Stable | 1/2+ | 1 | |||||||||||||
| 20 F | 9 | 11 | 19.99998125(3) | 11.0062(80) s | β− | 20 Ne | 2+ | ||||||||||||
| 21 F | 9 | 12 | 20.9999489(19) | 4.158(20) s | β− | 21 Ne | 5/2+ | ||||||||||||
| 22 F | 9 | 13 | 22.002999(13) | 4.23(4) s | β− (> 89%) | 22 Ne | (4+) | ||||||||||||
| β−n (< 11%) | 21 Ne | ||||||||||||||||||
| 23 F | 9 | 14 | 23.003530(40) | 2.23(14) s | β− (> 86%) | 23 Ne | 5/2+ | ||||||||||||
| β−n (< 14%) | 22 Ne | ||||||||||||||||||
| 24 F | 9 | 15 | 24.008100(100) | 384(16) ms | β− (> 94.1%) | 24 Ne | 3+ | ||||||||||||
| β−n (< 5.9%) | 23 Ne | ||||||||||||||||||
| 25 F | 9 | 16 | 25.012170(100) | 80(9) ms | β− (76.9(4.5)%) | 25 Ne | (5/2+) | ||||||||||||
| β−n (23.1(4.5)%) | 24 Ne | ||||||||||||||||||
| β−2n ?[n 8] | 23 Ne ? | ||||||||||||||||||
| 26 F | 9 | 17 | 26.020050(110) | 8.2(9) ms | β− (86.5(4.0)%) | 26 Ne | 1+ | ||||||||||||
| β−n (13.5(4.0)%) | 25 Ne | ||||||||||||||||||
| β−2n ?[n 8] | 24 Ne ? | ||||||||||||||||||
| 26m F | 643.4(1) keV | 2.2(1) ms | IT (82(11)%) | 26 F | (4+) | ||||||||||||||
| β−n (12(8)%) | 25 Ne | ||||||||||||||||||
| β− ?[n 8] | 26 Ne ? | ||||||||||||||||||
| 27 F | 9 | 18 | 27.026980(130) | 5.0(2) ms | β−n (77(21)%) | 26 Ne | 5/2+# | ||||||||||||
| β− (23(21)%) | 27 Ne | ||||||||||||||||||
| β−2n ?[n 8] | 25 Ne ? | ||||||||||||||||||
| 28 F | 9 | 19 | 28.035860(130) | 46 zs | n | 27 F | (4−) | ||||||||||||
| 29 F | 9 | 20 | 29.043100(560) | 2.5(3) ms | β−n (60(40)%) | 28 Ne | (5/2+) | ||||||||||||
| β− (40(40)%) | 29 Ne | ||||||||||||||||||
| β−2n ?[n 8] | 27 Ne ? | ||||||||||||||||||
| 31 F | 9 | 22 | 31.06020(570)# | 2 ms# [> 260 ns] | β− ?[n 8] | 31 Ne ? | 5/2+# | ||||||||||||
| β−n ?[n 8] | 30 Ne ? | ||||||||||||||||||
| β−2n ?[n 8] | 29 Ne ? | ||||||||||||||||||
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Fluorine-18
Of the unstable nuclides of fluorine, 18
F
has the longest half-life, 109.734(8) min. It decays to 18
O
via β+ decay. For this reason 18
F
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.)[7]
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 20
Ne
. 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 21
Ne
, 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.[4] The half-life of 18m
F
before it undergoes isomeric transition is 162(7) nanoseconds.[4] 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. [8] The half-life of 26m
F
is 2.2(1) milliseconds; it decays mainly to its ground state of 26
F
or (rarely, via beta-minus decay) to one of high excited states of 26
Ne
with delayed neutron emission.[4]
External links
References
Sources
- Chisté, V.; Bé, M. M. (2011). "F-18" (PDF). In Bé, M. M.; Coursol, N.; Duchemin, B.; Lagoutine, F.; et al. (eds.). Table de radionucléides (Report). CEA (Commissariat à l'énergie atomique et aux énergies alternatives), LIST, LNE-LNHB (Laboratoire National Henri Becquerel/Commissariat à l'Energie Atomique). Archived from the original (PDF) on 11 August 2020. Retrieved 15 June 2011.