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Isotopes of Actinium

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

 

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.

 

Isotope Table: Actinium

 

Atomic Properties

Isotope
Nuclide
ZANNameAtomic Mass
[Nuclear Mass]
{Mass Excess}
Spin I
(h/2π)
μParent
123456789
205Ac89205116Actinium-205205.01514(5) u
[204.9663226 u]
{14.10282 MeV}
206Ac89206117Actinium-206206.01447(5) u
[205.9656526 u]
{13.47872 MeV}
(3+)
206m1Ac89206117Actinium-206m1206.01447(5) u
[205.9656526 u]
{13.47872 MeV}
(10-)
207Ac89207118Actinium-207207.01197(5) u
[206.9631526 u]
{11.14998 MeV}
(9/2-)
208Ac89208119Actinium-208208.01154(6) u
[207.9627226 u]
{10.74944 MeV}
(3+)212Pa
208mAc89208119Actinium-208m208.01154(6) u
[207.9627226 u]
{10.74944 MeV}
(10-)
209Ac89209120Actinium-209209.00949(5) u
[208.9606726 u]
{8.83988 MeV}
(9/2-)213Pa
210Ac89210121Actinium-210210.00944(6) u
[209.9606226 u]
{8.7933 MeV}
7+214Pa
210Th
211Ac89211122Actinium-211211.00773(6) u
[210.9589126 u]
{7.20045 MeV}
9/2-215Pa
211Th
212Ac89212123Actinium-212212.00781(6) u
[211.9589926 u]
{7.27497 MeV}
(7+)+5.0(3)216Pa
212Th
213Ac89213124Actinium-213213.006607(16) u
[212.9577896 u]
{6.15438 MeV}
(9/2-)+4.2(4)217Pa
213Th
214Ac89214125Actinium-214214.006918(16) u
[213.9581006 u]
{6.44408 MeV}
(5+)+4.83(20)218Pa
215Ac89215126Actinium-215215.006474(13) u
[214.9576566 u]
{6.03049 MeV}
9/2-+4.14(6)219Pa
215m1Ac89215126Actinium-215m1215.006474(13) u
[214.9576566 u]
{6.03049 MeV}
(21/2-)9.66(20)
215,2Ac89215126Actinium-215,2215.006474(13) u
[214.9576566 u]
{6.03049 MeV}
(29/2+)15.13(30)
216Ac89216127Actinium-216216.008743(12) u
[215.9599256 u]
{8.14405 MeV}
(1-)220Pa
216Th
216mAc89216127Actinium-216m216.008743(12) u
[215.9599256 u]
{8.14405 MeV}
(9-)
217Ac89217128Actinium-217217.009344(12) u
[216.9605266 u]
{8.70388 MeV}
9/2-+3.83(5)221Pa
217mAc89217128Actinium-217m217.009344(12) u
[216.9605266 u]
{8.70388 MeV}
(29/2)++5.03(7)
218Ac89218129Actinium-218218.01164(5) u
[217.9628226 u]
{10.84259 MeV}
(1-)222Pa
218mAc89218129Actinium-218m218.01164(5) u
[217.9628226 u]
{10.84259 MeV}
(11+)
219Ac89219130Actinium-219219.01242(5) u
[218.9636026 u]
{11.56916 MeV}
9/2-223Pa
220Ac89220131Actinium-220220.014754(7) u
[219.9659366 u]
{13.74326 MeV}
(3-)224Pa
220Th
221Ac89221132Actinium-221221.01559(5) u
[220.9667726 u]
{14.52199 MeV}
(3/2-)225Pa
222Ac89222133Actinium-222222.017844(6) u
[221.9690266 u]
{16.62158 MeV}
1-226Pa
222mAc89222133Actinium-222m222.017844(6) u
[221.9690266 u]
{16.62158 MeV}
223Ac89223134Actinium-223223.019137(8) u
[222.9703196 u]
{17.826 MeV}
(5/2-)227Pa
225Ac89225136Actinium-225225.023229(5) u
[224.9744116 u]
{21.63767 MeV}
(3/2-)229Pa
225Th
225Ra
226Ac89226137Actinium-226226.026097(3) u
[225.9772796 u]
{24.3092 MeV}
(1)230Pa
227Ac89227138Actinium-227227.0277507(21) u
[226.9789333 u]
{25.84961 MeV}
3/2-+ 1.1(1)231Pa
227Ra
228Ac89228139Actinium-228228.0310198(22) u
[227.9822024 u]
{28.89476 MeV}
3+228Ra
229Ac89229140Actinium-229229.032947(13) u
[228.9841296 u]
{30.68993 MeV}
(3/2+)229Ra
230Ac89230141Actinium-230230.036327(17) u
[229.9875096 u]
{33.83838 MeV}
(1+)230Ra
231Ac89231142Actinium-231231.038393(14) u
[230.9895756 u]
{35.76285 MeV}
1/2+231Ra
232Ac89232143Actinium-232232.042034(14) u
[231.9932166 u]
{39.15442 MeV}
(1+)232Ra
233Ac89233144Actinium-233233.044346(14) u
[232.9955286 u]
{41.30803 MeV}
(1/2+)233Ra
234Ac89234145Actinium-234234.048139(15) u
[233.9993216 u]
{44.84119 MeV}
(1+)234Ra
235Ac89235146Actinium-235235.050840(15) u
[235.0020226 u]
{47.35715 MeV}
1/2+~
236Ac89236147Actinium-236236.05499(4) u
[236.0061726 u]
{51.22286 MeV}

 

Radioactive Decay Properties

IsotopeRadioactive DecayAEExtern
Half-lifeDecay ModeProbabilityEnergy
1101112131415
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 %290 keVAL
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 %

506(26) keVAL
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) ns1796.0(9) keV
Ac-215m2335(10) ns2438+x keV
Ac-216440(16) μsα → 212Fr100 %9.235(6) MeVAL
Ac-216m441(7) μsα → 212Fr100 %48(7) keVAL
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) %

2012.2(7) keVAL
Ac-2181.08(9) μsα → 214Fr100 %9.38(5) MeVAL
Ac-218m103(11) ns384.49(13)+yAL
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 %7.78(5) 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 %


0.0+xAL
Ac-2232.10(5) minα → 219Fr
EC → 223Ra
99 %
1 %
6.7832(10) MeV
0.593(7) 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 - nuclide, isotope symbol.
2 - Z = number of protons (atomic number).
3 - Mass number A.
4 - N = number of neutrons.
5 - Identification of the Actinium isotope.
6 - 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.
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 Actinium 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 Actinium 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)
227Ac
100 %
3/2-
+ 1,1(1)3,5+ 170(20)5,60,01131
0,6565

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 Actinium radionuclides:

NuclideLimit ValueHASS limitSCDaughter NuclidesHalf-life
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.

 


Category: Isotopes

Last update: 05.07.2020



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