Isotopes of fluorine

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 mononuclidic element.

Isotopes of fluorine (₉F)

Main isotopes Decay abun­dance half-life (t1/2) mode pro­duct 18F trace 109.734 min β+ 18O 19F 100% stable [1]
Standard atomic weight Ar°(F)
	18.998403162±0.000000005[2] 18.998±0.001 (abridged)[3]
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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  ?
30 F [7]	9	21	30.05256(54)#	0.96+0.56 −0.41 zs	n	29 F
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  ?
This table header & footer: view

1. ^mF – 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. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
5. Modes of decay:

   EC:	Electron capture
   IT:	Isomeric transition
   n:	Neutron emission
   p:	Proton emission

6. Bold symbol as daughter – Daughter product is stable.
7. ( ) spin value – Indicates spin with weak assignment arguments.
8. Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.
9. Intermediate product of various CNO cycles in stellar nucleosynthesis as part of the process producing helium from hydrogen
10. Has medicinal uses

Fluorine-18

Main article: 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.)^[8]

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. ^[9] 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]

References

1. Chisté & Bé 2011.
2. "Standard Atomic Weights: Fluorine". CIAAW. 2021.
3. 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.
4. 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.
5. 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.
6. 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.
7. Kahlbow, J.; et al. (SAMURAI21-NeuLAND Collaboration) (2024-08-23). "Magicity versus Superfluidity around ²⁸O viewed from the Study of ³⁰F". Physical Review Letters. 133 (8). arXiv:2407.19303. doi:10.1103/PhysRevLett.133.082501. ISSN 0031-9007.
8. National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
9. Audi, G.; Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S. (2017). "The NUBASE2016 evaluation of nuclear properties" (PDF). Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001.

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.