Isotopes of fluorine
From Wikipedia, the free encyclopedia
Fluorine (9F) has 19 known isotopes ranging from 13
F to 31
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 a mononuclidic element.
The longest-lived radioisotope is 18
F with a half-life of 109.734 minutes, followed by 17
F with 64.37 seconds. These unstable isotopes participate in the CNO cycle within stars. All other fluorine isotopes have half-lives of less than 12 seconds, and most of those less than 1/2 second.
List of isotopes
| Nuclide [n 1] |
Z | N | Isotopic mass (Da)[4] [n 2][n 3] |
Discovery year[5][6] |
Half-life[1] [n 4] |
Decay mode[1] [n 5] |
Daughter isotope [n 6] |
Spin and parity[1] [n 7][n 4] |
Isotopic abundance | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Excitation energy | |||||||||||||||||||
| 13 F[7] |
9 | 4 | 13.045120(540)# | 2021 | p ? | 12 O |
1/2+# | ||||||||||||
| 14 F |
9 | 5 | 14.034320(40) | 2010 | 500(60) ys [910(100) keV] |
p ? | 13 O |
2− | |||||||||||
| 15 F |
9 | 6 | 15.017785(15) | 1978 | 1.1(3) zs [376 keV] |
p | 14 O |
1/2+ | |||||||||||
| 16 F |
9 | 7 | 16.011460(6) | 1964 | 21(5) zs [21.3(5.1) keV] |
p | 15 O |
0− | |||||||||||
| 17 F[n 8] |
9 | 8 | 17.00209524(27) | 1934 | 64.370(27) s | β+ | 17 O |
5/2+ | |||||||||||
| 18 F[n 9] |
9 | 9 | 18.0009373(5) | 1937 | 109.734(8) min | β+ | 18 O |
1+ | Trace | ||||||||||
| 18m F |
1121.36(15) keV | 1959 | 162(7) ns | IT | 18 F |
5+ | |||||||||||||
| 19 F |
9 | 10 | 18.998403162067(883) | 1920 | Stable | 1/2+ | 1 | ||||||||||||
| 20 F |
9 | 11 | 19.99998125(3) | 1935 | 11.0062(80) s | β− | 20 Ne |
2+ | |||||||||||
| 21 F |
9 | 12 | 20.9999489(19) | 1955 | 4.158(20) s | β− | 21 Ne |
5/2+ | |||||||||||
| 22 F |
9 | 13 | 22.002999(13) | 1965 | 4.23(4) s | β− (> 89%) | 22 Ne |
(4+) | |||||||||||
| β−n (< 11%) | 21 Ne | ||||||||||||||||||
| 23 F |
9 | 14 | 23.003530(40) | 1970 | 2.23(14) s | β− (> 86%) | 23 Ne |
5/2+ | |||||||||||
| β−n (< 14%) | 22 Ne | ||||||||||||||||||
| 24 F |
9 | 15 | 24.008100(100) | 1970 | 384(16) ms | β− (> 94.1%) | 24 Ne |
3+ | |||||||||||
| β−n (< 5.9%) | 23 Ne | ||||||||||||||||||
| 25 F |
9 | 16 | 25.012170(100) | 1970 | 80(9) ms | β− (76.9(4.5)%) | 25 Ne |
(5/2+) | |||||||||||
| β−n (23.1(4.5)%) | 24 Ne | ||||||||||||||||||
| β−2n ? | 23 Ne ? | ||||||||||||||||||
| 26 F |
9 | 17 | 26.020050(110) | 1979 | 8.2(9) ms | β− (86.5(4.0)%) | 26 Ne |
1+ | |||||||||||
| β−n (13.5(4.0)%) | 25 Ne | ||||||||||||||||||
| β−2n ? | 24 Ne ? | ||||||||||||||||||
| 26m F |
643.4(1) keV | 2013 | 2.2(1) ms | IT (82(11)%) | 26 F |
(4+) | |||||||||||||
| β−n (12(8)%) | 25 Ne | ||||||||||||||||||
| β− ? | 26 Ne ? | ||||||||||||||||||
| 27 F |
9 | 18 | 27.026980(130) | 1981 | 5.0(2) ms | β−n (77(21)%) | 26 Ne |
5/2+# | |||||||||||
| β− (23(21)%) | 27 Ne | ||||||||||||||||||
| β−2n ? | 25 Ne ? | ||||||||||||||||||
| 28 F |
9 | 19 | 28.035860(130) | 2012 | 46 zs | n | 27 F |
(4−) | |||||||||||
| 29 F |
9 | 20 | 29.043100(560) | 1989 | 2.5(3) ms | β−n (60(40)%) | 28 Ne |
(5/2+) | |||||||||||
| β− (40(40)%) | 29 Ne | ||||||||||||||||||
| β−2n ? | 27 Ne ? | ||||||||||||||||||
| 30 F[8] |
9 | 21 | 30.05256(54)# | 2024 | 0.96+0.56 −0.41 zs |
n | 29 F |
||||||||||||
| 31 F |
9 | 22 | 31.06020(570)# | 1999 | 2 ms# [> 260 ns] | β− ? | 31 Ne ? |
5/2+# | |||||||||||
| β−n ? | 30 Ne ? | ||||||||||||||||||
| β−2n ? | 29 Ne ? | ||||||||||||||||||
| 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).
- # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
- Modes of decay:
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.
- Intermediate product of various CNO cycles in stellar nucleosynthesis as part of the process producing helium from hydrogen
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 second lightest unstable nuclide (after beryllium-8, with 4 protons and 4 neutrons) with equal numbers of protons and neutrons and lightest such with an odd atomic number, having 9 of each. (See also the parity discussion of nuclide stability.)[9]
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.
Isomers
Only two nuclear isomers (long-lived excited nuclear states), fluorine-18m and fluorine-26m, have been characterized. The half-life of 18m
F before it undergoes isomeric transition is 162(7) nanoseconds. This is less than the decay half-life of any of the particle-bound fluorine radioisotope nuclear ground states. 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.
See also
Daughter products other than fluorine