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Isotopes of Actinium

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

Content
Atomic properties
Decay properties
NMR active nuclides
Radiation protection
References
Actinium isotopes

All atomic nuclei of the chemical element actinium are summarized under actinium isotopes; these consist of an atomic nucleus with 89 protons and in the uncharged state of 89 electrons. The difference between the individual actinium isotopes lies in the number of neutrons in the nucleus.

The radioactive element actinium only has unstable ones, the longest-lived of which has a half-life of less than 21.8 years.

Small amounts of actinium-227 and actinium-228 (mesothorium II) are found in nature as intermediates in radioactive decay chains emanating from uranium-235 and thorium-232, respectively. By far the largest proportion of natural actinium is provided by the isotope 227.

The individual actinium isotopes are of little practical importance; on the one hand, this is due to the high production costs and, on the other hand, to the high level of radioactivity that these nuclides emit. The isotope with mass number 225 can be used as an alpha emitter for the medical treatment of certain types of cancer.

The following data collection provides the most important properties of all actinium isotopes: These include, among other things, the atomic properties and information on the radioactive decays. Further values for the individual Ac isotopes - if necessary with the graphic representation of the decay series - can be found on the linked data sheets.

 

Isotope Table: Actinium

The two following tables list the most important data and properties of the Actinium isotopes. Further information on the individual Actinium 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
Actinium-20420489Ac115204 u
[203.9511826 u]
{0 MeV}
Actinium-20520589Ac116205.01514(5) u
[204.9663226 u]
{14.10282 MeV}
Actinium-20620689Ac117206.01447(5) u
[205.9656526 u]
{13.47872 MeV}		(3+)
Actinium-206m1206m189Ac117206.01447(5) u
[205.9656526 u]
{13.47872 MeV}		(10-)
Actinium-20720789Ac118207.01197(5) u
[206.9631526 u]
{11.14998 MeV}		(9/2-)
Actinium-20820889Ac119208.01154(6) u
[207.9627226 u]
{10.74944 MeV}		(3+)212Pa
Actinium-208m208m89Ac119208.01154(6) u
[207.9627226 u]
{10.74944 MeV}		(10-)
Actinium-20920989Ac120209.00949(5) u
[208.9606726 u]
{8.83988 MeV}		(9/2-)213Pa
Actinium-21021089Ac121210.00944(6) u
[209.9606226 u]
{8.7933 MeV}		7+214Pa
210Th
Actinium-21121189Ac122211.00773(6) u
[210.9589126 u]
{7.20045 MeV}		9/2-215Pa
211Th
Actinium-21221289Ac123212.00781(6) u
[211.9589926 u]
{7.27497 MeV}		(7+)216Pa
212Th
Actinium-21321389Ac124213.006607(16) u
[212.9577896 u]
{6.15438 MeV}		(9/2-)217Pa
213Th
Actinium-21421489Ac125214.006918(16) u
[213.9581006 u]
{6.44408 MeV}		(5+)218Pa
Actinium-21521589Ac126215.006474(13) u
[214.9576566 u]
{6.03049 MeV}		9/2-219Pa
Actinium-215m1215m189Ac126215.006474(13) u
[214.9576566 u]
{6.03049 MeV}		(21/2-)
Actinium-215m2215m289Ac126215.006474(13) u
[214.9576566 u]
{6.03049 MeV}		(29/2+)
Actinium-21621689Ac127216.008743(12) u
[215.9599256 u]
{8.14405 MeV}		(1-)220Pa
216Th
Actinium-216m216m89Ac127216.008743(12) u
[215.9599256 u]
{8.14405 MeV}		(9-)
Actinium-21721789Ac128217.009344(12) u
[216.9605266 u]
{8.70388 MeV}		9/2-221Pa
Actinium-217m217m89Ac128217.009344(12) u
[216.9605266 u]
{8.70388 MeV}		(29/2)+
Actinium-21821889Ac129218.01164(5) u
[217.9628226 u]
{10.84259 MeV}		(1-)222Pa
Actinium-218m218m89Ac129218.01164(5) u
[217.9628226 u]
{10.84259 MeV}		(11+)
Actinium-21921989Ac130219.01242(5) u
[218.9636026 u]
{11.56916 MeV}		9/2-223Pa
Actinium-22022089Ac131220.014754(7) u
[219.9659366 u]
{13.74326 MeV}		(3-)224Pa
220Th
Actinium-22122189Ac132221.01559(5) u
[220.9667726 u]
{14.52199 MeV}		(3/2-)225Pa
Actinium-22222289Ac133222.017844(6) u
[221.9690266 u]
{16.62158 MeV}		1-226Pa
Actinium-222m222m89Ac133222.017844(6) u
[221.9690266 u]
{16.62158 MeV}
Actinium-22322389Ac134223.019137(8) u
[222.9703196 u]
{17.826 MeV}		(5/2-)227Pa
Actinium-22422489Ac135224.021722(4) u
[223.9729046 u]
{20.23391 MeV}		(0-)228Pa
Actinium-22522589Ac136225.023229(5) u
[224.9744116 u]
{21.63767 MeV}		(3/2-)229Pa
225Th
225Ra
Actinium-22622689Ac137226.026097(3) u
[225.9772796 u]
{24.3092 MeV}		(1)230Pa
Actinium-22722789Ac138227.0277507(21) u
[226.9789333 u]
{25.84961 MeV}		3/2-231Pa
227Ra
Actinium-22822889Ac139228.0310198(22) u
[227.9822024 u]
{28.89476 MeV}		3+228Ra
Actinium-22922989Ac140229.032947(13) u
[228.9841296 u]
{30.68993 MeV}		(3/2+)229Ra
Actinium-23023089Ac141230.036327(17) u
[229.9875096 u]
{33.83838 MeV}		(1+)230Ra
Actinium-23123189Ac142231.038393(14) u
[230.9895756 u]
{35.76285 MeV}		1/2+231Ra
Actinium-23223289Ac143232.042034(14) u
[231.9932166 u]
{39.15442 MeV}		(1+)232Ra
Actinium-23323389Ac144233.044346(14) u
[232.9955286 u]
{41.30803 MeV}		(1/2+)233Ra
Actinium-23423489Ac145234.048139(15) u
[233.9993216 u]
{44.84119 MeV}		(1+)234Ra
Actinium-23523589Ac146235.050840(15) u
[235.0020226 u]
{47.35715 MeV}		1/2+~
Actinium-23623689Ac147236.05499(4) u
[236.0061726 u]
{51.22286 MeV}

 

Radioactive Decay Properties

IsotopeRadioactive DecayExtern
Half-lifeDecay ModeProbabilityEnergy
789101112
Ac-2047.4 msα → 200Fr?AL
Ac-20520(+97-9) msα → 201Frca. 100 %8.09(5) MeVAL
Ac-20622(+9-5) msα → 202Fr100 %7.96(5) MeVAL
Ac-206m133(+22-9) msα → 202Fr100 %AL
Ac-20727(+11-6) msα → 203Fr100 %7.84(5) MeVAL
Ac-20895(+24-16) msα → 204Fr
EC → 208Ra		99 %
1 %		7.72(5) MeV
9.03(6) MeV		AL
Ac-208m25(+9-5)msα → 204Fr
β+ → 208Ra		90 %
10 %
AL
Ac-20987 msα → 205Fr~100 %7.73(5) MeVAL
Ac-2100.35(5) sα → 206Fr
EC/β+ → 210Ra		91 %
9 %		7.61(5) MeV
8.35(6) MeV		AL
Ac-2110.21(3) sα → 207Fr
EC/β+ → 211Ra		> 99.8 %
< 0.2 %		7.62(5) MeV
6.37(5) MeV		AL
Ac-2120.93(5) sα → 208Fr
EC → 212Ra		57 %
43 %		7.52(5) MeV
7.48(5) MeV		AL
Ac-213738(16) msα → 209Fr
&spsilon; → 213Ra		> 99 %
<< 1 %		7.499(4) MeV
?		AL
Ac-2148.2(2) sα → 210Fr
EC → 214Ra		> 89(3) %
< 11(3) %		7.3521(25) MeV
6.351(16) MeV		AL
Ac-2150.17(1) sα → 211Fr
EC/β+ → 215Ra		99.91(2) %
0.09(2) %		7.746(3) MeV
3.497(15) MeV		AL
Ac-215m1185(30) ns
Ac-215m2335(10) ns
Ac-216440(16) μsα → 212Fr100 %9.235(6) MeVAL
Ac-216m441(7) μsα → 212Fr100 %AL
Ac-21769(4) nsα → 213Fr
EC/β+ → 217Ra		> 98 %
< 2 %		9.832(10) MeV
2.814(13) MeV		AL
Ac-217m740(40) nsα → 213Fr
Iso → 217Ac		4.51(18) %
95.49(18) %
AL
Ac-2181.08(9) μsα → 214Fr100 %9.38(5) MeVAL
Ac-218m103(11) nsAL
Ac-21911.8(15) μsα → 215Fr100 %8.83(5) MeVAL
Ac-22026.4(2) msα → 216Fr
EC → 220Ra		> 99 %
5×10-4 %		8.348(4) MeV
3.473(10) MeV		AL
Ac-22152(2) msα → 217Fr100 %7.791(57) MeVAL
Ac-2225.0(5) sα → 218Fr
EC/β+ → 222Ra		99(1) %
1(1) %		7.1374(20) MeV
2.301(7) MeV		AL
Ac-222m63(3) sα → 218Fr
β+ → 222Ra
Iso → 222Ac		> 88 %
> 0.7(2) %
< 10 %

AL
Ac-2232.10(5) minα → 219Fr
EC → 223Ra		99 %
1 %		6.7832(10) MeV
0.593(7) MeV		AL
Ac-2242.78(16) hα → 220Fr
EC → 224Ra		9.1 %
90.9 %		6.3269(7) MeV
1.408(4) MeV		AL
Ac-2259.9203(3) dα → 221Fr
CD → 14C		> 99 %
<< 1 %		5.9351(14) MeV
AL
Ac-22629.37(12) hα → 222Fr
EC → 226Ra
β- → 226Th		<< 1 %
17(3) %
83(3) %		5.506(8) MeV
0.641(4) MeV
1.112(5) MeV		AL
Ac-22721.772(3) aα → 223Fr
β- → 227Th		1.3800(36) %
98.6200(36) %		5.04227(14) MeV
0.0448(8) MeV		AL
Ac-2286.15(2) hβ- → 228Th100 %2.1237(26) MeVAL
Ac-22962.7(5) minβ- → 229Th100 %1.104(12) MeVAL
Ac-230122(3) sβ- → 230Th100 %2.976(16) MeVAL
Ac-2317.5(1) minβ- → 231Th100 %1.947(13) MeVAL
Ac-232119(5) sβ- → 232Th100 %3.708(13) MeVAL
Ac-233145(10) sβ- → 233Th100 %2.576(13) MeVAL
Ac-23444(7) sβ- → 234Th100 %4.228(14) MeVAL
Ac-23562(4) sβ- → 235Th100 %3.339(19) MeVAL
Ac-2361.2(+58-5) minβ- → 236Th100 %4.97(4) MeVAL

 

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 Actinium 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 Actinium 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 Actinium 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)
227Ac
100 %
3/2-		+ 1,1(1)3,5
{+ 1,7(2)}		5,60,01131
0,6565

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 Actinium radionuclides:

NuclideLimit ValueHASS limitSCDaughter NuclidesHalf-life
Ac-224+106 Bq100 Bq/g2.8 h
Ac-225+104 Bq10 Bq/gFr-221; At-217; Bi-213
Po-213; Tl-209; Pb-209		10.0 d
Ac-226+105 Bq100 Bq/g29.4 h
Ac-227+103 Bq0,01 Bq/g0,04 TBq1 Bq cm-2Fr-22321.8 a
Ac-228+106 Bq10 Bq/g0,03 TBq1 Bq cm-2Fr-223; Th-227; Ra-223
Rn-219; Po-215; Pb-211
Bi-211; Tl-207; Po-211		6.2 h
Ac-228106 Bq10 Bq/g6 × 109 Bq1 Bq/cm26.1 h

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

 

Literature Sources and References

Properties of the Actinium 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.

Actinium: NMR properties - 227Ac-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] - C. Fry, M. Thoennessen:
Discovery of actinium, thorium, protactinium, and uranium isotopes.
In: Atomic Data and Nuclear Data Tables, (2013), DOI 10.1016/j.adt.2012.03.002.

 

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