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Isotopes of Francium

List, data and properties of all known isotopes of Francium.

Content
Atomic properties
Decay properties
NMR active nuclides
Radiation protection
References
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

The two following tables list the most important data and properties of the Francium isotopes. Further information on the individual Francium isotopes is listed on separate pages and can be accessed via the link in column 1.

 

Atomic Properties

Isotope
Nuclide		ENAtomic Mass
[Nuclear Mass]
{Mass Excess}		Spin I
(h/2π)		Parent
123456
Francium-19919987Fr112199.007269(15) u
[198.9595484 u]
{6.77103 MeV}		1/2+
Francium-20020087Fr113200.00658(3) u
[199.9588594 u]
{6.12923 MeV}		(3+)
Francium-20120187Fr114201.003852(10) u
[200.9561314 u]
{3.58811 MeV}		(9/2-)
Francium-20220287Fr115202.003324(8) u
[201.9556034 u]
{3.09629 MeV}		(3+)206Ac
Francium-202m202m87Fr115202.003324(8) u
[201.9556034 u]
{3.09629 MeV}		(10-)
Francium-20320387Fr116203.000941(7) u
[202.9532204 u]
{0.87654 MeV}		(9/2-)207Ac
Francium-20420487Fr117204.000652(26) u
[203.9529314 u]
{0.60733 MeV}		(3+)208Ac
Francium-204m1204m187Fr117204.000652(26) u
[203.9529314 u]
{0.60733 MeV}		(7+)
Francium-204m2204m287Fr117204.000652(26) u
[203.9529314 u]
{0.60733 MeV}		(10-)
Francium-20520587Fr118204.998594(8) u
[204.9508734 u]
{-1.30968 MeV}		(9/2-)209Ac
Francium-20620687Fr119205.99867(3) u
[205.9509494 u]
{-1.23889 MeV}		(2+,3+)210Ac
Francium-206m1206m187Fr119205.99867(3) u
[205.9509494 u]
{-1.23889 MeV}		(7+)
Francium-206m2206m287Fr119205.99867(3) u
[205.9509494 u]
{-1.23889 MeV}		(10-)
Francium-20720787Fr120206.996946(19) u
[206.9492254 u]
{-2.84478 MeV}		9/2-211Ac
Francium-20820887Fr121207.997138(13) u
[207.9494174 u]
{-2.66594 MeV}		7+212Ac
Francium-20920987Fr122208.995953(16) u
[208.9482324 u]
{-3.76976 MeV}		9/2-213Ac
Francium-21021087Fr123209.996422(16) u
[209.9487014 u]
{-3.33289 MeV}		6+214Ac
Francium-21121187Fr124210.995555(13) u
[210.9478344 u]
{-4.14049 MeV}		9/2-215Ac
Francium-21221287Fr125211.996225(9) u
[211.9485044 u]
{-3.51639 MeV}		5+216Ac
Francium-21321387Fr126212.996184(5) u
[212.9484634 u]
{-3.55458 MeV}		9/2-217Ac
213Ra
Francium-21421487Fr127213.998971(9) u
[213.9512504 u]
{-0.95851 MeV}		(1-)218Ac
214Ra
Francium-214m1214m187Fr127213.998971(9) u
[213.9512504 u]
{-0.95851 MeV}		(8-)
Francium-214m2214m287Fr127213.998971(9) u
[213.9512504 u]
{-0.95851 MeV}		(11+)
Francium-21521587Fr128215.000341(8) u
[214.9526204 u]
{0.31764 MeV}		9/2-219Ac
Francium-21621687Fr129216.003189(4) u
[215.9554684 u]
{2.97053 MeV}		(1-)220Ac
Francium-21721787Fr130217.004632(7) u
[216.9569114 u]
{4.31468 MeV}		9/2-221Ac
Francium-21821887Fr131218.007578(5) u
[217.9598574 u]
{7.05886 MeV}		1-222Ac
Francium-218m218m87Fr131218.007578(5) u
[217.9598574 u]
{7.05886 MeV}
Francium-21921987Fr132219.009252(8) u
[218.9615314 u]
{8.61818 MeV}		9/2-223Ac
Francium-22022087Fr133220.012327(4) u
[219.9646064 u]
{11.48253 MeV}		1+224Ac
Francium-22122187Fr134221.014254(5) u
[220.9665334 u]
{13.27752 MeV}		5/2-225Ac
221Rn
Francium-22222287Fr135222.017583(8) u
[221.9698624 u]
{16.37846 MeV}		2-226Ac
Francium-22322387Fr136223.0197343(21) u
[222.9720137 u]
{18.38238 MeV}		3/2(-)227Ac
223Rn
Francium-22422487Fr137224.023348(12) u
[223.9756274 u]
{21.74852 MeV}		1(-)224Rn
Francium-22522587Fr138225.025572(13) u
[224.9778514 u]
{23.82016 MeV}		3/2-225Rn
Francium-22622687Fr139226.029545(7) u
[225.9818244 u]
{27.52099 MeV}		1-226Rn
Francium-22722787Fr140227.031865(6) u
[226.9841444 u]
{29.68206 MeV}		1/2+227Rn
Francium-22822887Fr141228.035839(7) u
[227.9881184 u]
{33.38381 MeV}		2-228Rn
Francium-22922987Fr142229.038291(5) u
[228.9905704 u]
{35.66784 MeV}
Francium-23023087Fr143230.042391(7) u
[229.9946704 u]
{39.48696 MeV}
Francium-23123187Fr144231.045175(8) u
[230.9974544 u]
{42.08024 MeV}		(1/2+)
Francium-23223287Fr145232.049461(15) u
[232.0017404 u]
{46.07262 MeV}		(5)
Francium-23323387Fr146233.052518(21) u
[233.0047974 u]
{48.9202 MeV}

 

Radioactive Decay Properties

IsotopeRadioactive DecayExtern
Half-lifeDecay ModeProbabilityEnergy
789101112
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 %AL
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) %
AL
Fr-204m20.8(2) sα → 200At
EC/β+ → 204Rn		74(8) %
26(8) %
AL
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 %
AL
Fr-206m20.7(1) sα → 202At
Iso → 206Fr		ca. 5 %
ca. 95 %
AL
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-21334.17(6) sα → 209At
EC/β+ → 213Rn		99.44(5) %
0.56(5) %		6.9047(13) MeV
2.142(6) MeV		AL
Fr-2145.0(2) msα → 210At100 %8.589(4) MeVAL
Fr-214m13.35(5) msα → 210At100 %AL
Fr-214m2103(4) nsAL
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 %
?
AL
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 - name of the nuclide, isotope.
2 - E: isotope symbol with mass number (superscript; number of nucleons) and Atomic number (subscript; number of protons).
3 - N: number of neutrons.
4 - 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.
5 - nuclear spin I, unit: h/2π.
6 - 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.

7 - isotope notation in short form.
8 - decay: half-live of the Francium isotope (a = years; ; d = days; h = hours; min = minutes; s = seconds).
9 - decay mode: 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.
10 - decay probability in percent (%).
11 - decay energy; Particle energy related to decay type.
12 - 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
{Quadrupole moment}		Resonant
frequency
v0 bei 1 T		Relative
sensitivity
H0 = const.
v0 = const. 3)
223Fr
100 %
3/2(-)		+ 1,17(2)
{1,17(1)}		5,940,01362
0,6982

1) Quantity Percentage of natural occurrence.

2) Gyromagnetic ratio: 107 rad T-1 s-1
    Quadrupole moment: Q [barn] = [100 fm2]

3) 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.

 

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