Fluorine-31

Properties and data of the isotope ³¹F.

Contents

Fluorine-31 is a radioisotope of the chemical element fluorine, which, in addition to the element-specific 9 protons, has 22 neutrons in the atomic nucleus, resulting in the mass number 31. The extremely short-lived and neutron-rich nuclide, which can only be produced artificially, is unstable and therefore radioactive, has no practical significance; The study of ³¹F serves exclusively academic purposes.

The first observation of the neutron-rich and extremely unstable isotope was reported in 1999; according to this, fluorine-31 was formed by the fragmentation of a Ta sample with argon-40 ions (94.1 MeV per nucleon) [2].

See also: List of individual Fluorine isotopes (and general data sources).

General data

Name of the isotope:Fluorine-31; F-31Symbol:³¹F or 319FMass number A:31 (= number of nucleons)Atomic number Z:9 (= number of protons)Neutrons N:22Isotopic mass:31.061020(570) u (atomic weight of Fluorine-31)Nuclide mass:31.0560828 u (calculated nuclear mass without electrons)Mass excess:56.83976 MeVMass defect:0.20003344 u (per nucleus)Nuclear binding energy:186.32994916 MeV (per nucleus)
6.01064352 MeV (average binding energy per nucleon)Separation energy:S_N = 0.189(732) MeV (first neutron)Half-life:> 260 nsDecay constant λ:2665950.6944613 s^-1Specific activity α:5.178945357320 × 10⁺²⁸ Bq g^-1
1.399714961437 × 10⁺¹⁸ Ci g^-1Spin and parity:
(nuclear angular momentum)Year of discovery:1998

Radioactive Decay

Half-life T_½ = > 260 ns respectively 2.60 × 10^-7 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	³¹Ne	< 100 %	25.66(60) MeV
β^-, xn		?	x =1-7

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 22) and isobaric (same nucleon number A = 31) with Fluorine-31. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 22	Isobar A = 31
9	³¹F	³¹F
10	³²Ne	³¹Ne
11	³³Na	³¹Na
12	³⁴Mg	³¹Mg
13	³⁵Al	³¹Al
14	³⁶Si	³¹Si
15	³⁷P	³¹P
16	³⁸S	³¹S
17	³⁹Cl	³¹Cl
18	⁴⁰Ar	³¹Ar
19	⁴¹K
20	⁴²Ca
21	⁴³Sc
22	⁴⁴Ti
23	⁴⁵V
24	⁴⁶Cr
25	⁴⁷Mn
26	⁴⁸Fe
27	⁴⁹Co
28	⁵⁰Ni

External data and identifiers

Adopted Levels, Gammas:NuDat 32F

Literature and References

[1] - H. Sakurai, S. M. Lukyanov, M. Notani et al.:
New neutron-rich isotope ³¹F and particle instability of ²⁵N and ²⁸O.
In: AIP Conference Proceedings, (1998), DOI 10.1063/1.57323.

[2] - H. Sakurai et al.:
Evidence for particle stability of ³¹F and particle instability of ²⁵N and ²⁸O.
In: Physics Letters B, 448(3-4), (1999), DOI 10.1016/S0370-2693(99)00015-5.

[3] - N. Michel, J. G. Li, F. R. Xu, W. Zuo:
Two-neutron halo structure of ³¹F.
In: Physical Review C, (2020), DOI 10.1103/PhysRevC.101.031301.

[4] - Hiroshi Masui, Wataru Horiuchi, Masaaki Kimura:
Two-Neutron Halo Structure and Anti-halo Effect in ³¹F.
In: Few-Body Systems, 63, 20, (2021), DOI 10.1007/s00601-021-01715-z.