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Isotopes of Thallium

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

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

All atomic nuclei of the chemical element thallium are summarized under thallium isotopes; these all consist of an atomic nucleus with 81 protons and, in the uncharged state, 81 electrons. The difference between each thallium isotope is based on the number of neutrons in the nucleus.

 

Naturally Occurring Thallium Isotopes

Natural terrestrial thallium deposits essentially consist of the two stable isotopes thallium-203 and thallium-205; in addition, the smallest traces of the radioisotopes Tl-206, Tl-207, Tl-208 and Tl-210 can be detected as short-lived intermediate products of radioactive decay processes.

Atomic Mass maQuantityHalf-lifeSpin
Thallium
Isotopic mixture		204,38 u100 %
Isotope 203Tl202,972345(9) u29,52(1) %stable1/2+
Isotope 205Tl204,974428(9) u70,48(1) %stable1/2+

 

A large number of other thallium isotopes and nuclear isomers have been described to date, all of which are unstable and decay with the emission of radioactive radiation.

 

Isotope Table: Thallium

The two following tables list the most important data and properties of the Thallium isotopes. Further information on the individual Thallium 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
Thallium-17617681Tl95176.00062(8) u
[175.95619 u]
{0.57753 MeV}		(3-,4-,5-)
Thallium-17717781Tl96176.996414(23) u
[176.951984 u]
{-3.34034 MeV}		(1/2+)
Thallium-177m177m81Tl96176.996414(23) u
[176.951984 u]
{-3.34034 MeV}		(11/2-)
Thallium-17817881Tl97177.99486(10) u
[177.95043 u]
{-4.78788 MeV}
Thallium-17917981Tl98178.99112(4) u
[178.94669 u]
{-8.27167 MeV}		(1/2+)
Thallium-179m179m81Tl98178.99112(4) u
[178.94669 u]
{-8.27167 MeV}		(11/2-)
Thallium-18018081Tl99179.98992(6) u
[179.94549 u]
{-9.38946 MeV}		(5-)184Bi
Thallium-18118181Tl100180.98626(1) u
[180.94183 u]
{-12.79873 MeV}		(1/2+)185Bi
Thallium-181m181m81Tl100180.98626(1) u
[180.94183 u]
{-12.79873 MeV}		(9/2-)
Thallium-18218281Tl101181.985692(13) u
[181.941262 u]
{-13.32782 MeV}		(7+)
Thallium-18318381Tl102182.982193(10) u
[182.937763 u]
{-16.58711 MeV}		(1/2+)187Bi
Thallium-183m1183m181Tl102182.982193(10) u
[182.937763 u]
{-16.58711 MeV}		(9/2-)
Thallium-183m2183m281Tl102182.982193(10) u
[182.937763 u]
{-16.58711 MeV}		(13/2+)
Thallium-18418481Tl103183.981875(11) u
[183.937445 u]
{-16.88333 MeV}		188Bi
Thallium-18518581Tl104184.978789(22) u
[184.934359 u]
{-19.75792 MeV}		(1/2+)189Bi
Thallium-185m185m81Tl104184.978789(22) u
[184.934359 u]
{-19.75792 MeV}		(9/2-)
Thallium-18618681Tl105185.978651(24) u
[185.934221 u]
{-19.88647 MeV}		(7+)
Thallium-18718781Tl106186.975905(9) u
[186.931475 u]
{-22.44435 MeV}		(1/2+)191Bi
187Pb
Thallium-187m187m81Tl106186.975905(9) u
[186.931475 u]
{-22.44435 MeV}		(9/2-)
Thallium-18818881Tl107187.97602(3) u
[187.93159 u]
{-22.33723 MeV}		(2-)192Bi
188Pb
Thallium-188m1188m181Tl107187.97602(3) u
[187.93159 u]
{-22.33723 MeV}		(7+)
Thallium-188m2188m281Tl107187.97602(3) u
[187.93159 u]
{-22.33723 MeV}		9-
Thallium-18918981Tl108188.973574(9) u
[188.929144 u]
{-24.61566 MeV}		(1/2+)193Bi
Thallium-189m189m81Tl108188.973574(9) u
[188.929144 u]
{-24.61566 MeV}		(9/2-)
Thallium-19019081Tl109189.973836(9) u
[189.929406 u]
{-24.37161 MeV}		2(-)194Bi
190Pb
Thallium-190m1190m181Tl109189.973836(9) u
[189.929406 u]
{-24.37161 MeV}		7(+)
Thallium-190m2190m281Tl109189.973836(9) u
[189.929406 u]
{-24.37161 MeV}		(8-)
Thallium-19119181Tl110190.971784(8) u
[190.927354 u]
{-26.28303 MeV}		(1/2+)195Bi
191Pb
Thallium-191m191m81Tl110190.971784(8) u
[190.927354 u]
{-26.28303 MeV}		9/2(-)
Thallium-19219281Tl111191.97222(3) u
[191.92779 u]
{-25.8769 MeV}		(2-)196Bi
192Pb
Thallium-192m1192m181Tl111191.97222(3) u
[191.92779 u]
{-25.8769 MeV}		(7+)
Thallium-192m2192m281Tl111191.97222(3) u
[191.92779 u]
{-25.8769 MeV}		(8-)
Thallium-19319381Tl112192.970502(7) u
[192.926072 u]
{-27.47721 MeV}		1/2(+)197Bi
193Pb
Thallium-193m193m81Tl112192.970502(7) u
[192.926072 u]
{-27.47721 MeV}		(9/2-)
Thallium-19419481Tl113193.971081(15) u
[193.926651 u]
{-26.93787 MeV}		2-194Pb
Thallium-194m194m81Tl113193.971081(15) u
[193.926651 u]
{-26.93787 MeV}		(7+)
Thallium-19519581Tl114194.969774(12) u
[194.925344 u]
{-28.15534 MeV}		1/2+199Bi
195Pb
Thallium-195m195m81Tl114194.969774(12) u
[194.925344 u]
{-28.15534 MeV}		9/2-
Thallium-19619681Tl115195.970481(13) u
[195.926051 u]
{-27.49677 MeV}		2-196Pb
Thallium-196m196m81Tl115195.970481(13) u
[195.926051 u]
{-27.49677 MeV}		(7+)
Thallium-19719781Tl116196.969574(18) u
[196.925144 u]
{-28.34164 MeV}		1/2+197Pb
201Bi
Thallium-197m197m81Tl116196.969574(18) u
[196.925144 u]
{-28.34164 MeV}		9/2-
Thallium-19819881Tl117197.970447(8) u
[197.926017 u]
{-27.52844 MeV}		2-198Pb
Thallium-198m1198m181Tl117197.970447(8) u
[197.926017 u]
{-27.52844 MeV}		7+
Thallium-198m2198m281Tl117197.970447(8) u
[197.926017 u]
{-27.52844 MeV}		(5,7,9)+
Thallium-198m3198m381Tl117197.970447(8) u
[197.926017 u]
{-27.52844 MeV}		(10-)
Thallium-19919981Tl118198.96988(3) u
[198.92545 u]
{-28.0566 MeV}		1/2+199Pb
Thallium-199m199m81Tl118198.96988(3) u
[198.92545 u]
{-28.0566 MeV}		9/2-
Thallium-20020081Tl119199.970964(6) u
[199.926534 u]
{-27.04686 MeV}		2-200Pb
Thallium-200m1200m181Tl119199.970964(6) u
[199.926534 u]
{-27.04686 MeV}		7+
Thallium-200m2200m281Tl119199.970964(6) u
[199.926534 u]
{-27.04686 MeV}		5+
Thallium-20120181Tl120200.970820(15) u
[200.92639 u]
{-27.18099 MeV}		1/2+201Pb
Thallium-201m201m81Tl120200.970820(15) u
[200.92639 u]
{-27.18099 MeV}		(9/2-)
Thallium-20220281Tl121201.9721091(17) u
[201.9276791 u]
{-25.98021 MeV}		2-202Pb
Thallium-202m202m81Tl121201.9721091(17) u
[201.9276791 u]
{-25.98021 MeV}		7+
Thallium-20320381Tl122202.972345(9) u
[202.927915 u]
{-25.76047 MeV}		1/2+203Pb
203Hg
Thallium-20420481Tl123203.9738633(12) u
[203.9294333 u]
{-24.34618 MeV}		2-
Thallium-204m1204m181Tl123203.9738633(12) u
[203.9294333 u]
{-24.34618 MeV}		(7)+
Thallium-20520581Tl124204.974428(9) u
[204.929998 u]
{-23.82016 MeV}		1/2+205Pb
205Hg
209Bi
Thallium-205m1205m181Tl124204.974428(9) u
[204.929998 u]
{-23.82016 MeV}		25/2+
Thallium-205m2205m281Tl124204.974428(9) u
[204.929998 u]
{-23.82016 MeV}		(35/2-)
Thallium-20620681Tl125205.9761100(14) u
[205.93168 u]
{-22.25339 MeV}		0-206Hg
210Bi
Thallium-206m206m81Tl125205.9761100(14) u
[205.93168 u]
{-22.25339 MeV}		(12-)
Thallium-20720781Tl126206.977419(6) u
[206.932989 u]
{-21.03407 MeV}		1/2+207Hg
211Bi
Thallium-207m207m81Tl126206.977419(6) u
[206.932989 u]
{-21.03407 MeV}		11/2-
Thallium-20820881Tl127207.9820180(20) u
[207.937588 u]
{-16.75013 MeV}		5+208Hg
212Bi
Thallium-20920981Tl128208.985352(7) u
[208.940922 u]
{-13.64452 MeV}		1/2+213Bi
Thallium-21021081Tl129209.990073(12) u
[209.945643 u]
{-9.24694 MeV}		(5+)214Bi
Thallium-21121181Tl130210.993470(4) u
[210.94904 u]
{-6.08266 MeV}
Thallium-21221281Tl131211.99833(21) u
[211.9539 u]
{-1.55559 MeV}		(5+)
Thallium-21321381Tl132213.001915(29) u
[212.957485 u]
{1.78381 MeV}
Thallium-21421481Tl133214.00694(21) u
[213.96251 u]
{6.46457 MeV}
Thallium-21521581Tl134215.01064(32) u
[214.96621 u]
{9.9111 MeV}
Thallium-21621681Tl135216.01580(32) u
[215.97137 u]
{14.71761 MeV}
Thallium-21721781Tl136217.01966(43) u
[216.97523 u]
{18.31317 MeV}

 

Radioactive Decay Properties

IsotopeRadioactive DecayExtern
Half-lifeDecay ModeProbabilityEnergy
789101112
Tl-176ca. 5.2 msp → 175Hg~100 %AL
Tl-17718(5) msα → 173Au
p → 176Hg		73(13) %
27(13) %		7.067(7) MeV
9.45 MeV		AL
Tl-177m230(40) μsp → 176Hg
α → 173Au		51(8) %
49(8) %
Tl-178ca. 254 msα → 174Au
EC/β+ → 178Hg		ca. 53 %
ca. 47 %		7.02(1) MeV
11.53(9) MeV		AL
Tl-1790.23(4) sα → 175Au
EC/β+ → 179Hg
p → 178Hg		< 100 %
?
?		6.711(3) MeV
8.66(5) MeV
AL
Tl-179m1.5(3) msα → 175Au
p → 178Hg
EC/β+ → 180Hg
Iso → 179Tl		< 100 %
?
?
?
Tl-1801.09(1) sα → 176Au
EC/β+ → 180Hg
EC, SF → div		6(4) %
94(4) %
0.0032(2) %		6.71(5) MeV
10.86(6) MeV
AL
Tl-1813.2(3) sα → 177Au≤ 10 %6.321(6) MeVAL
Tl-181m1.40(3) msIso → 181Tl
α → 177Au		99.60(4) %
0.40(6) %
Tl-1823.1(10) sα → 178Au
EC/β+ → 182Hg		?
97.5(25) %		6.551(6) MeV
10.249(15) MeV		AL
Tl-1836.9(7) sα → 179Au
EC/β+ → 183Hg		?
> 0 %		5.976(9) MeV
7.217(12) MeV		AL
Tl-183m153.3(3) msα → 179Au
EC/β+ → 183Hg
Iso → 183Tl		1.5(3) %
?
?
Tl-183m21.48(19) μsIso → 183TTl100 %
Tl-18410.1(5) sα → 180Au
EC/β+ → 184Hg		2.1(7) %
97.9(7) %		6.317(9) MeV
9.466(14) MeV		AL
Tl-18519.5(5) sEC/β+ → 185Hg?6.426(25) MeVAL
Tl-185m1.93(8) sα → 181Au
Iso → 185Tl		?
?
Tl-18627.5(10) sEC/β+ → 186Hg
α → 182Au		ca. 100 %
0.006 %		8.652(25) MeV
5.99(3) MeV		AL
Tl-187ca. 51 sEC/β+ → 187Hg
α → 183Au		ca. 100 %
0.03 %		5.673(16) MeV
5.322(7) MeV		AL
Tl-187m15.60(12) sEC/β+ → 187Hg
α → 183Au
Iso → 187Tl		0.15(5) %
?
< 99.9 %
Tl-18871(2) sEC/β+ → 188Hg100 %7.87(3) MeVAL
Tl-188m171.5(15) sEC/β+ → 188Hg100 %
Tl-188m241(4) msIso → 188Tl100 %
Tl-1892.3(2) minEC/β+ → 189Hg100 %5.01(3) MeVAL
Tl-189m1.4(1) minEC/β+ → 189Hg
Iso → 189Tl		98(2) %
2 % ?
Tl-1902.6(3) minEC/β+ → 190Hg100 %6.999(18) MeVAL
Tl-190m13.7(3) minEC/β+ → 190Hg100 %
Tl-190m20.75(4) msIso → 190Tl100 %
Tl-191AL
Tl-191m5.22(16) minEC → 191Hg100 %
Tl-1929.6(4) minEC/β+ → 192Hg100 %6.14(4) MeVAL
Tl-192m110.8(2) minEC/β+ → 192Hg100 %
Tl-192m2296(5) nsIso → 192Tl100 %
Tl-19321.6(8) minEC/β+ → 193Hg100 %3.585(17) MeVAL
Tl-193m2.11(15) minEC/β+ → 193Hg
Iso → 193Tl		≥ 25 %
≤ 75 %
Tl-19433.0(5) minEC/β+ → 194Hg
α → 190Au		> 99 %
Spuren		5.246(14) MeV
3.471(14) MeV		AL
Tl-194m32.8(2) minEC/β+ → 194Hg100 %
Tl-1951.16(5) hEC/β+ → 195Hg100 %2.858(26) MeVAL
Tl-195m3.6(4) sIso → 195Tl100 %
Tl-1961.84(3) hEC/β+ → 196Hg100 %4.329(12) MeVAL
Tl-196m1.41(2) hEC/β+ → 196Hg
Iso → 196Tl		96.2(4) %
3.8(4) %
Tl-1972.84(4) hEC/β+ → 197Hg100 %2.199(17) MeVAL
Tl-197m0.54(1) sIso → 197Tl100 %
Tl-1985.3(5) hEC/β+ → 198Hg100 %3.426(8) MeVAL
Tl-198m11.87(3) hEC/β+ → 198Hg
Iso → 198Tl		55.9(23) %
44.1(23) %
Tl-198m2150(40) ns
Tl-198m332.1(10) msIso → 198Tl100 %
Tl-1997.42(8) hEC/β+ → 199Hg100 %1.487(28) MeVAL
Tl-199m28.4(2) msIso → 199Tl100 %
Tl-20026.1(1) hEC/β+ → 200Hg100 %2.456(6) MeVAL
Tl-200m134.0(9) msIso → 200Tl100 %
Tl-200m20.33(5) μs
Tl-2013.0420(16) dEC → 201Hg100 %0.482(14) MeVAL
Tl-201m2.11(11) msIso → 201Tl100 %
Tl-20212.31(8) dEC/β+ → 202Hg100 %1.3651(18) MeVAL
Tl-202m591(3) μsIso → 202Tl100 %
Tl-203stableAL
Tl-2043.783(12) aEC/β+ → 204Hg
β- → 204Pb		2.92(7) %
97.08(7) %		0.3440(12) MeV
0.76375(18) MeV		AL
Tl-204m161.7(10) μsIso → 204Tl100 %
Tl-205stableAL
Tl-205m12.6(2) μs
Tl-205m2235(10) ns
Tl-2064.202(11) minβ- → 206Pb100 %1.5322(6) MeVAL
Tl-206m3.74(3) minIso → 206Tl100 %
Tl-2074.77(3) minβ- → 207Pb100 %1.418(5) MeVAL
Tl-207m1.33(11) sIso → 207Tl100 %
Tl-2083.053(4) minβ- → 208Pb100 %4.9985(17) MeVAL
Tl-2092.167(7) minβ- → 209Pb100 %3.970(6) MeVAL
Tl-2101.30(3) minβ- → 210Pb
β-, n → 209Pb		99.993 %
0.007 %		5.482(12) MeV
0.296(12) MeV		AL
Tl-21188 sβ- → 211Pb
β-, n → 210Pb
?		4.41(4) MeV
0.58(4) MeV		AL
Tl-212ca. 96 sβ- → 212Pb
β-, n → 211Pb
6.0(2) MeV
0.87(20) MeV		AL
Tl-213ca. 46 sβ- → 213Pb
β-, n → 212Pb
?		4.987(28) MeV
1.261(27) MeV		AL
Tl-214> 300 nsβ- → 214Pb
β-, n → 213Pb		?
P		6.65(20) MeV
1.6(2) MeV		AL
Tl-215> 300 nsβ- → 215Pb
β-, n → 214Pb		?
?		5.57(30) MeV
2.02(30) MeV		AL
Tl-216> 300 nsβ- → 216Pb
β-, n → 215Pb		?
?		7.24(36) MeV
2.3(3) MeV		AL
Tl-217> 300 nsβ- → 217Pb
β-, n → 216Pb
?		6.07(50) MeV
2.76(45) MeV		AL

 

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 Thallium 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 Thallium 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 Thallium 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)
203Tl
29,52(1) %
1/2+		+ 1,62225787(12)15,5394
{}		24,73160,19598
0,5809
205Tl
70,48(1) %
1/2+		+ 1,638214615,6922
{}		24,97490,20182
0,5866

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 Thallium radionuclides:

NuclideLimit ValueHASS limitSCDaughter NuclidesHalf-life
Tl-194106 Bq10 Bq/g33.0 min
Tl-194m106 Bq10 Bq/g32.8 min
Tl-195106 Bq10 Bq/g1.2 h
Tl-197106 Bq100 Bq/g2.8 h
Tl-198106 Bq10 Bq/g5.3 h
Tl-198m106 Bq10 Bq/g1.9 h
Tl-199106 Bq100 Bq/g7.4 h
Tl-200106 Bq10 Bq/g0,05 TBq1 Bq cm-226.1 h
Tl-201106 Bq100 Bq/g1 TBq10 Bq cm-273.0 h
Tl-202106 Bq10 Bq/g0,2 TBq10 Bq cm-212.2 d
Tl-204104 Bq1 Bq/g20 TBq100 Bq cm-23.8 a

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

 

Literature Sources and References

Properties of the Thallium 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.

Thallium: NMR properties - 203Tl-NMR, 205Tl-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] - Sune G. Nielsen, Mark Rehkämper, Joel Baker, Alex N. Halliday:
The precise and accurate determination of thallium isotope compositions and concentrations for water samples by MC-ICPMS.
In: Chemical Geology, (2004), DOI 10.1016/j.chemgeo.2003.11.006.

[10] - Sune Groenlund Nielsen:
Thallium isotope variations in terrestrial materials and meteorites.
In: Dissertation, ETH Zürich, (2005), DOI 10.3929/ethz-a-005026208.

[11] - Sune G. Nielsen et al.:
Thallium isotopes as a potential tracer for the origin of cratonic eclogites.
In: Geochimica et Cosmochimica Acta, (2009), DOI 10.1016/j.gca.2009.09.001.

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