Isotopes of fluorine

Fluorine (9F) has 18 known isotopes ranging from 13Fluorine to 31Fluorine (with the exception of 30Fluorine) and two isomers (18mFluorine and 26mFluorine). 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 [[Fluorine|18Fluorine]]; it has a half-life of $109.734 minutes$. 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 14Fluorine, whose half-life is $500 yoctoseconds$, corresponding to a resonance width of $910 keV$.

List of isotopes

 * 13Fluorine
 * style="text-align:right" | 9
 * style="text-align:right" | 4
 * p ?
 * 12Oxygen ?
 * 1/2+#
 * 14Fluorine
 * style="text-align:right" | 9
 * style="text-align:right" | 5
 * $13.045$ [$14.034$]
 * p ?
 * 13Oxygen ?
 * 2−
 * 15Fluorine
 * style="text-align:right" | 9
 * style="text-align:right" | 6
 * $500 ys$ [$910 keV$]
 * p
 * 14Oxygen
 * 1/2+
 * 16Fluorine
 * style="text-align:right" | 9
 * style="text-align:right" | 7
 * $15.018$ [$1.1 zs$]
 * p
 * 15Oxygen
 * 0−
 * 17Fluorine
 * style="text-align:right" | 9
 * style="text-align:right" | 8
 * β+
 * 17Oxygen
 * 5/2+
 * [[Fluorine|18Fluorine]]
 * style="text-align:right" | 9
 * style="text-align:right" | 9
 * β+
 * 18Oxygen
 * 1+
 * Trace
 * style="text-indent:1em" | 18mFluorine
 * colspan="3" style="text-indent:2em" | $376 keV$
 * IT
 * 18Fluorine
 * 5+
 * 19Fluorine
 * style="text-align:right" | 9
 * style="text-align:right" | 10
 * colspan=3 align=center|Stable
 * 1/2+
 * 1
 * 20Fluorine
 * style="text-align:right" | 9
 * style="text-align:right" | 11
 * β−
 * 20Neon
 * 2+
 * 21Fluorine
 * style="text-align:right" | 9
 * style="text-align:right" | 12
 * β−
 * 21Neon
 * 5/2+
 * rowspan=2|22Fluorine
 * rowspan=2 style="text-align:right" | 9
 * rowspan=2 style="text-align:right" | 13
 * rowspan=2|$376 keV$
 * rowspan=2|$376 keV$
 * β− (> $376 keV$)
 * 22Neon
 * rowspan=2|(4+)
 * rowspan=2|
 * β−n (< $16.011$)
 * 21Neon
 * rowspan=2|23Fluorine
 * rowspan=2 style="text-align:right" | 9
 * rowspan=2 style="text-align:right" | 14
 * rowspan=2|$21 zs$
 * rowspan=2|$21.3 keV$
 * β− (> $17.002$)
 * 23Neon
 * rowspan=2|5/2+
 * rowspan=2|
 * β−n (< $64.37 s$)
 * 22Neon
 * rowspan=2|24Fluorine
 * rowspan=2 style="text-align:right" | 9
 * rowspan=2 style="text-align:right" | 15
 * rowspan=2|$18.001$
 * rowspan=2|$109.734 min$
 * β− (> $1,121.36 keV$)
 * 24Neon
 * rowspan=2|3+
 * rowspan=2|
 * β−n (< $162 ns$)
 * 23Neon
 * rowspan=3|25Fluorine
 * rowspan=3 style="text-align:right" | 9
 * rowspan=3 style="text-align:right" | 16
 * rowspan=3|$18.998$
 * rowspan=3|$20$
 * β− ($11.006 s$)
 * 25Neon
 * rowspan=3|(5/2+)
 * rowspan=3|
 * β−n ($21$)
 * 24Neon
 * β−2n ?
 * 23Neon ?
 * rowspan=3|26Fluorine
 * rowspan=3 style="text-align:right" | 9
 * rowspan=3 style="text-align:right" | 17
 * rowspan=3|$4.158 s$
 * rowspan=3|$22.003$
 * β− ($4.23 s$)
 * 26Neon
 * rowspan=3|1+
 * rowspan=3|
 * β−n ($89 %$)
 * 25Neon
 * β−2n ?
 * 24Neon ?
 * rowspan=3 style="text-indent:1em" | 26mFluorine
 * rowspan=3 colspan="3" style="text-indent:2em" | $11 %$
 * rowspan=3 | $23.004$
 * IT ($2.23 s$)
 * 26Fluorine
 * rowspan=3|(4+)
 * rowspan=3|
 * β−n ($86 %$)
 * 25Neon
 * β− ?
 * 26Neon ?
 * rowspan=3|27Fluorine
 * rowspan=3 style="text-align:right" | 9
 * rowspan=3 style="text-align:right" | 18
 * rowspan=3|$14 %$
 * rowspan=3|$24.008$
 * β−n ($384 ms$)
 * 26Neon
 * rowspan=3|5/2+#
 * rowspan=3|
 * β− ($94.1 %$)
 * 27Neon
 * β−2n ?
 * 25Neon ?
 * 28Fluorine
 * style="text-align:right" | 9
 * style="text-align:right" | 19
 * n
 * 27Fluorine
 * (4−)
 * rowspan=3|29Fluorine
 * rowspan=3 style="text-align:right" | 9
 * rowspan=3 style="text-align:right" | 20
 * rowspan=3|$5.9 %$
 * rowspan=3|$25.012$
 * β−n ($80 ms$)
 * 28Neon
 * rowspan=3|(5/2+)
 * rowspan=3|
 * β− ($76.9 %$)
 * 29Neon
 * β−2n ?
 * 27Neon ?
 * rowspan=3|31Fluorine
 * rowspan=3 style="text-align:right" | 9
 * rowspan=3 style="text-align:right" | 22
 * rowspan=3|$23.1 %$#
 * rowspan=3|$26.02$# [> $8.2 ms$]
 * β− ?
 * 31Neon ?
 * rowspan=3|5/2+#
 * rowspan=3|
 * β−n ?
 * 30Neon ?
 * β−2n ?
 * 29Neon ?
 * β− ?
 * 26Neon ?
 * rowspan=3|27Fluorine
 * rowspan=3 style="text-align:right" | 9
 * rowspan=3 style="text-align:right" | 18
 * rowspan=3|$86.5 %$
 * rowspan=3|$13.5 %$
 * β−n ($643.4 keV$)
 * 26Neon
 * rowspan=3|5/2+#
 * rowspan=3|
 * β− ($2.2 ms$)
 * 27Neon
 * β−2n ?
 * 25Neon ?
 * 28Fluorine
 * style="text-align:right" | 9
 * style="text-align:right" | 19
 * n
 * 27Fluorine
 * (4−)
 * rowspan=3|29Fluorine
 * rowspan=3 style="text-align:right" | 9
 * rowspan=3 style="text-align:right" | 20
 * rowspan=3|$82 %$
 * rowspan=3|$12 %$
 * β−n ($27.027$)
 * 28Neon
 * rowspan=3|(5/2+)
 * rowspan=3|
 * β− ($5 ms$)
 * 29Neon
 * β−2n ?
 * 27Neon ?
 * rowspan=3|31Fluorine
 * rowspan=3 style="text-align:right" | 9
 * rowspan=3 style="text-align:right" | 22
 * rowspan=3|$77 %$#
 * rowspan=3|$23 %$# [> $28.036$]
 * β− ?
 * 31Neon ?
 * rowspan=3|5/2+#
 * rowspan=3|
 * β−n ?
 * 30Neon ?
 * β−2n ?
 * 29Neon ?
 * rowspan=3 style="text-align:right" | 9
 * rowspan=3 style="text-align:right" | 22
 * rowspan=3|$46 zs$#
 * rowspan=3|$29.043$# [> $2.5 ms$]
 * β− ?
 * 31Neon ?
 * rowspan=3|5/2+#
 * rowspan=3|
 * β−n ?
 * 30Neon ?
 * β−2n ?
 * 29Neon ?
 * β−2n ?
 * 29Neon ?

Fluorine-18
Of the unstable nuclides of fluorine, 18Fluorine has the longest half-life, $60 %$. It decays to 18Oxygen via β+ decay. For this reason 18Fluorine 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.)

Fluorine-19
Fluorine-19 is the only stable isotope of fluorine. Its abundance is $40 %$; no other isotopes of fluorine exist in significant quantities. Its binding energy is $31.06$. 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 $2 ms$ and decays via beta decay to the stable nuclide 20Neon. Its specific radioactivity is $260 ns$ and has a mean lifetime of $109.734 minutes$.

Fluorine-21
Fluorine-21, as with fluorine-20, is also an unstable isotope of fluorine. It has a half-life of $100 %$. It undergoes beta decay as well, decaying to 21Neon, which is a stable nuclide. Its specific activity is $147,801.365 keV$.

Isomers
Only two nuclear isomers (long-lived excited nuclear states), fluorine-18m and fluorine-26m, have been characterized. The half-life of 18mFluorine before it undergoes isomeric transition is $11.006 seconds$. 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. The half-life of 26mFluorine is $1.869 Bq/g$; it decays mainly to its ground state of 26Fluorine or (rarely, via beta-minus decay) to one of high excited states of 26Neon with delayed neutron emission.