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 a mononuclidic element.

Isotopes of fluorine (₉F)

Main isotopes Decay abun­dance half-life (t1/2) mode pro­duct 17F synth 64.37 s β+ 17O 18F trace 109.734 min β+ 18O 19F 100% stable
Standard atomic weight Ar°(F)
	18.998403162±0.000000005[1] 18.998±0.001 (abridged)[2]
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The longest-lived radioisotope is ¹⁸
F with a half-life of 109.734 u=minutes, followed by ¹⁷
F with 64.37 seconds. All other fluorine isotopes have half-lives of less than 12 seconds, and most of those less than 1/2 second. These unstable isotopes of fluorine, however, participate in the CNO cycle within stars.

List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da)[3] [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[5]	9	4	13.045120(540)#		p ?	12 O	1/2+#
14 F	9	5	14.034320(40)	500(60) ys [910(100) keV]	p ?	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 8]	9	8	17.00209524(27)	64.370(27) s	β+	17 O	5/2+
18 F[n 9]	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 ?	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 ?	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− ?	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 ?	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 ?	27 Ne ?
30 F[6]	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− ?	31 Ne ?	5/2+#
					β−n ?	30 Ne ?
					β−2n ?	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. Intermediate product of various CNO cycles in stellar nucleosynthesis as part of the process producing helium from hydrogen
9. 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 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.)^[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.

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

• Isotopes of neon
• Isotopes of oxygen