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Isotopes of Francium

List, data and properties of all known isotopes of Francium as well as radioactive decay products and intermediate products.

 

Francium isotopes

A total of 34 isotopes are known from the chemical element francium, all of which are unstable and therefore radioactive. The nuclides francium-221 and francium-223 are found in nature as radioactive intermediate products of various decay processes (actinium and neptunium decay series).

All francium isotopes are very short-lived; Francium-223 has the longest half-life at 22 minutes.

 

Isotope Table: Francium

 

Atomic Properties

Isotope
Nuclide
ZANNameAtomic Mass
[Nuclear Mass]
{Mass Excess}
Spin I
(h/2π)
μParent
123456789
199Fr87199112Francium-199199.007269(15) u
[198.9595484 u]
{6.77103 MeV}
1/2+
200Fr87200113Francium-200200.00658(3) u
[199.9588594 u]
{6.12923 MeV}
(3+)
201Fr87201114Francium-201201.003852(10) u
[200.9561314 u]
{3.58811 MeV}
(9/2-)
202Fr87202115Francium-202202.003324(8) u
[201.9556034 u]
{3.09629 MeV}
(3+)206Ac
202mFr87202115Francium-202m202.003324(8) u
[201.9556034 u]
{3.09629 MeV}
(10-)
203Fr87203116Francium-203203.000941(7) u
[202.9532204 u]
{0.87654 MeV}
(9/2-)207Ac
204Fr87204117Francium-204204.000652(26) u
[203.9529314 u]
{0.60733 MeV}
(3+)208Ac
204m1Fr87204117Francium-204m1204.000652(26) u
[203.9529314 u]
{0.60733 MeV}
(7+)
204m2Fr87204117Francium-204m2204.000652(26) u
[203.9529314 u]
{0.60733 MeV}
(10-)
205Fr87205118Francium-205204.998594(8) u
[204.9508734 u]
{-1.30968 MeV}
(9/2-)209Ac
206Fr87206119Francium-206205.99867(3) u
[205.9509494 u]
{-1.23889 MeV}
(2+,3+)210Ac
206m1Fr87206119Francium-206m1205.99867(3) u
[205.9509494 u]
{-1.23889 MeV}
(7+)
206m2Fr87206119Francium-206m2205.99867(3) u
[205.9509494 u]
{-1.23889 MeV}
(10-)
207Fr87207120Francium-207206.996946(19) u
[206.9492254 u]
{-2.84478 MeV}
9/2-+ 3.89(8)211Ac
208Fr87208121Francium-208207.997138(13) u
[207.9494174 u]
{-2.66594 MeV}
7+4.75(10)212Ac
209Fr87209122Francium-209208.995953(16) u
[208.9482324 u]
{-3.76976 MeV}
9/2-+ 3.95(8)213Ac
210Fr87210123Francium-210209.996422(16) u
[209.9487014 u]
{-3.33289 MeV}
6++ 4.40(9)214Ac
211Fr87211124Francium-211210.995555(13) u
[210.9478344 u]
{-4.14049 MeV}
9/2-+ 4.00(8)215Ac
212Fr87212125Francium-212211.996225(9) u
[211.9485044 u]
{-3.51639 MeV}
5+4.62(9)216Ac
213Fr87213126Francium-213212.996186(5) u
[212.9484654 u]
{-3.55272 MeV}
9/2-+ 4.02(8)217Ac
214Fr87214127Francium-214213.998971(9) u
[213.9512504 u]
{-0.95851 MeV}
(1-)218Ac
214Ra
214m1Fr87214127Francium-214m1213.998971(9) u
[213.9512504 u]
{-0.95851 MeV}
(8-)
214m2Fr87214127Francium-214m2213.998971(9) u
[213.9512504 u]
{-0.95851 MeV}
(11+)+5.62(7)
215Fr87215128Francium-215215.000341(8) u
[214.9526204 u]
{0.31764 MeV}
9/2-219Ac
216Fr87216129Francium-216216.003189(4) u
[215.9554684 u]
{2.97053 MeV}
(1-)220Ac
217Fr87217130Francium-217217.004632(7) u
[216.9569114 u]
{4.31468 MeV}
9/2-221Ac
218Fr87218131Francium-218218.007578(5) u
[217.9598574 u]
{7.05886 MeV}
1-222Ac
218mFr87218131Francium-218m218.007578(5) u
[217.9598574 u]
{7.05886 MeV}
219Fr87219132Francium-219219.009252(8) u
[218.9615314 u]
{8.61818 MeV}
9/2-223Ac
220Fr87220133Francium-220220.012327(4) u
[219.9646064 u]
{11.48253 MeV}
1+- 0.67(1)224Ac
221Fr87221134Francium-221221.014254(5) u
[220.9665334 u]
{13.27752 MeV}
5/2-+ 1.58(3)225Ac
221Rn
222Fr87222135Francium-222222.017583(8) u
[221.9698624 u]
{16.37846 MeV}
2-0.63(1)226Ac
223Fr87223136Francium-223223.0197343(21) u
[222.9720137 u]
{18.38238 MeV}
3/2(-)+ 1.17(2)227Ac
223Rn
224Fr87224137Francium-224224.023348(12) u
[223.9756274 u]
{21.74852 MeV}
1(-)+0.40(1)224Rn
225Fr87225138Francium-225225.025572(13) u
[224.9778514 u]
{23.82016 MeV}
3/2-1.07(2)225Rn
226Fr87226139Francium-226226.029545(7) u
[225.9818244 u]
{27.52099 MeV}
1-+ 0.0712(14)226Rn
227Fr87227140Francium-227227.031865(6) u
[226.9841444 u]
{29.68206 MeV}
1/2++ 1.50(3)227Rn
228Fr87228141Francium-228228.035839(7) u
[227.9881184 u]
{33.38381 MeV}
2-- 0.76(2)228Rn
229Fr87229142Francium-229229.038291(5) u
[228.9905704 u]
{35.66784 MeV}
230Fr87230143Francium-230230.042391(7) u
[229.9946704 u]
{39.48696 MeV}
231Fr87231144Francium-231231.045175(8) u
[230.9974544 u]
{42.08024 MeV}
(1/2+)
232Fr87232145Francium-232232.049461(15) u
[232.0017404 u]
{46.07262 MeV}
(5)
233Fr87233146Francium-233233.052518(21) u
[233.0047974 u]
{48.9202 MeV}

 

Radioactive Decay Properties

IsotopeRadioactive DecayAEExtern
Half-lifeDecay ModeProbabilityEnergy
1101112131415
Fr-199ca. 12 msEC/β+199Rn
α → 195At
?
> 0 %
8.27(4) MeV
7.817(10) MeV
AL
Fr-20049(4) msα → 196At100 %7.622(4) MeVAL
Fr-20162(5) msα → 197At100 %7.519(4) MeVAL
Fr-2020.30(5) sα → 198At100 %7.386(4) MeVAL
Fr-202m0.29(5) sα → 198At100 %+x keVAL
Fr-2030.55(1) sα → 199At≤ 100 %7.275(4) MeVAL
Fr-2041.8(3) sα → 200At
EC/β+204Rn
92(2) %
8(2) %
7.1703(24) MeV
8.578(26) MeV
AL
Fr-204m1ca. 1.6 sα → 200At
EC/β+204Rn
90(2) %
10(2) %

41(7) keVAL
Fr-204m20.8(2) sα → 200At
EC/β+204Rn
74(8) %
26(8) %

316(7) keVAL
Fr-2053.92(4) sα → 201At≤ 100 %7.0547(24) MeVAL
Fr-206ca. 16 sα → 202At
EC → 206Rn
ca. 84 %
ca. 16 %
6.923(3) MeV
7.891(29) MeV
AL
Fr-206m1ca. 16 sα → 202At
EC/β+206Rn
ca. 84 %
ca. 16 %

+x keVAL
Fr-206m20.7(1) sα → 202At
Iso → 206Fr
ca. 5 %
ca. 95 %

531+x keVAL
Fr-20714.8(1) sα → 203At
EC/β+207Rn
95(2) %
5(2) %
6.893(20) MeV
5.79(19) MeV
AL
Fr-20859.1(3) sα → 204At
EC/β+208Rn
89(3) %
11(3) %
6.785(24) MeV
6.99(16) MeV
AL
Fr-20950.5(7) sα → 205At
EC/β+209Rn
89(3) %
11(3) %
6.777(4) MeV
5.171(18) MeV
AL
Fr-2103.18(6) minα → 206At
EC/β+210Rn
60(30) %
40(30) %
6.672(5) MeV
6.272(16) MeV
AL
Fr-2113.10(2) minα → 207At
EC/β+211Rn
> 80 %
< 20 %
6.662(3) MeV
4.615(14) MeV
AL
Fr-21220.0(6) minα → 208At
EC/β+212Rn
43(2) %
57(2) %
6.5290(16) MeV
5.144(9) MeV
AL
Fr-21334.82(14) sα → 209At
EC/β+213Rn
99.44(5) %
0.56(5) %
6.9048(12) MeV
2.143(6) MeV
AL
Fr-2145.0(2) msα → 210At100 %8.589(4) MeVAL
Fr-214m13.35(5) msα → 210At100 %122(5) keVAL
Fr-214m2103(4) ns638(5) keVAL
Fr-21586(5) nsα → 211At100 %9.540(7) MeVAL
Fr-2160.70(2) μsα → 212At
EC → 216Rn
ca. 100 %
<< 1 %
9.174(3) MeV
2.718(7) MeV
AL
Fr-21722(5) μsα → 213At100 %8.469(4) MeVAL
Fr-2181.0(6) msα → 214At100 %8.0140(29) MeVAL
Fr-218m22.0(5) msα → 214At
Iso → 218Fr
< 100 %
?

86(8) keVAL
Fr-21920(2) msα → 215At100 %7.4486(18) MeVAL
Fr-22027.4(3) sα → 216At
β-220Ra
99.65(5) %
0.35(5) %
6.8007(19) MeV
1.212(9) MeV
AL
Fr-2214.9(2) minα → 217At
β-221Ra
> 99.9 %
< 0.1 %
6.4577(14) MeV
0.313(6) MeV
AL
Fr-22214.2(3) minβ-222Ra100 %2.058(9) MeVAL
Fr-22322.00(7) minβ-223Ra
α → 219At
99.994 %
0.006 %
1.1491(8) MeV
5.5614(28) MeV
AL
Fr-2243.33(10) minβ-224Ra100 %2.923(11) MeVAL
Fr-2253.95(14) minβ-225Ra100 %1.828(12) MeVAL
Fr-22649(1) sβ-226Ra100 %3.853(7) MeVAL
Fr-2272.47(3) minβ-227Ra100 %2.505(6) MeVAL
Fr-22838(1) sβ-228Ra≤ 100 %4.444(7) MeVAL
Fr-22950.2(20) sβ-229Ra100 %3.106(16) MeVAL
Fr-23019.1(5) sβ-230Ra100 %4.970(12) MeVAL
Fr-23117.6(6) sβ-231Ra100 %3.864(14)AL
Fr-2325.5(6) sβ-232Ra100 %5.576(17) MeVAL
Fr-2330.9(1) sβ-233Ra
β-, n → 232Ra
100 %
?
4.586(21) MeV
0.352(22) MeV

 

Notes (related to the columns):

1 - nuclide, isotope symbol.
2 - Z = number of protons (atomic number).
3 - Mass number A.
4 - N = number of neutrons.
5 - Identification of the Francium isotope.
6 - Relative atomic mass of the Francium isotope (isotopic mass including electrons) and the mass of the atomic nucleus in square brackets (nuclear mass, nuclide mass without electrons), each related to 12C = 12.00000 [2]. In addition, the mass excess is given in MeV.
7 - Nuclear spin I, unit: h/2π.
8 - Nuclear magnetic moment μmag.
9 - Source nuclides: Possible, assumed or actual source nuclides (mother nuclides, parent nuclides). If applicable, the corresponding decay modes can be found in the data for the respective starting nuclide.
10 - Decay: Half-live of the Francium isotope (a = years; ; d = days; h = hours; min = minutes; s = seconds).
11 - Decay: type of decay into the respective daughter nuclides with n = neutron emission; p = proton emission; α = alpha decay; β- = beta minus decay with electron emission; EC = electron capture; β+ = positron emission; ε = β+ and/or EC; Iso = isomeric transition; CD = cluster decay; SF = spontaneous decay.
12 - Decay percentage in percent (%).
13 - Decay energy; Particle energy related to decay type.
14 - AE = Excitation energy for metastable nuclei.
15 - Other information and notes: AL = Adopted Levels (link to external data [1]).

Miscellaneous:

()- Numbers in brackets: uncertainty to represent the spread of the reported value.
~ - Theoretical values or systematic trends.
  - unlisted-: Nuclides that have already been mentioned in the literature but for some reason can no longer be found in the current nuclide tables because their discovery e.g. has not confirmed.

 

NMR active Francium nuclides

Nuclide
quantity 1)
spin
Nuclear magnetic
moment
μ/μN
Gyromagnetic
ratio
107 rad T-1 s-1
Quadrupole
moment
Q fm-2
Resonant
frequency
v0 bei 1 T
Relative
sensitivity
H0 = const.
v0 = const. 2)
223Fr
100 %
3/2(-)
+ 1,17(2)117(1)5,940,01362
0,6982

1) Quantity Percentage of natural occurrence.

2) Related to 1H = 1,000.

 

Radiation Protection

According to the Radiation Protection Ordinance (StrlSchV 2018, Germany), the following values (columns 1 to 7) apply to the handling of Francium radionuclides:

NuclideLimit ValueHASS limitSCDaughter NuclidesHalf-life
Fr-222+105 Bq1000 Bq/g14.2 min
Fr-223106 Bq100 Bq/g21.8 min

(HASS = High-Activity Sealed Radioactive Sources; SC = surface contamination)

 

Literature Sources and References

Properties of the Francium nucleides

[1] - NuDat: National Nuclear Data Center, Brookhaven National Laboratory, based on ENSDF and the Nuclear Wallet Cards.

[2] - G. Audi et. al.: The NUBASE evaluation of nuclear and decay properties. Nuclear Physics, (2003), DOI 10.1016/j.nuclphysa.2003.11.001.

[3] - Live Chart of Nuclides. Nuclear structure and decay data.

Francium: NMR properties - 223Fr-NMR

[4] - N. J. Stone: Table of nuclear magnetic dipole and electric quadrupole moments. Atomic Data and Nuclear Data Tables, (2005), DOI 10.1016/j.adt.2005.04.001.

[5] - Pekka Pyykkö: Year-2008 nuclear quadrupole moments. Molecular Physics, (2008), DOI 10.1080/00268970802018367.

[6] - Pekka Pyykkö: Year-2017 nuclear quadrupole moments. Molecular Physics, (2018), DOI 10.1080/00268976.2018.1426131.

[7] - N. J. Stone: Table of recommended nuclear magnetic dipole moments. IAEA, (2019).

More sources:

[8] - Isotopic abundances, atomic weights and isotopic masses: see respective keyword.

[9] - Roger D. Griffioen, Ronald D. Macfarlane:
Alpha-Decay Properties of Some Francium Isotopes Near the 126-Neutron Closed Shell.
In: Physical Review, (1964), DOI 10.1103/PhysRev.133.B1373.

[10] - C. Ekström et al.:
Nuclear Ground State Spins of the Francium Isotopes 208-213, 220-222Fr.
In: Physica Scripta, (1978), DOI 10.1088/0031-8949/18/1/014.

[11] - Mina Vajed-Samii et al.:
Accurate Values of Nuclear Magnetic Moments of Francium Isotopes.
In: Physical Review Letters, (1982), DOI 10.1103/PhysRevLett.49.1800.

[12] - J. S. Grossman et al.:
Spectroscopy of francium isotopes.
In: Physica Scripta, (2000), DOI 10.1238/Physica.Topical.086a00016.

[13] - Ann-Marie Martensson-Pendrilla:
Charge radii in francium isotopes.
In: Molecular Physics, (2000), DOI 10.1080/00268970050080555.

[14] - NN:
Spectroscopic Data for Neutral Francium (Fr I).
In: Journal of Physical and Chemical Reference Data, (2007), DOI 10.1063/1.2719251.

 


Category: Isotopes

Last update: 05.07.2020



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