Thorium-229

Properties and data of the isotope ²²⁹Th.

Content

General Data

Radioactive Decay

Parent Nuclides

NMR Data

Isotones und Isobares

Literature

General data

Name of the isotope:Thorium-229; Th-229Symbol:²²⁹Th or 22990ThMass number A:229 (= number of nucleons)Atomic number Z:90 (= number of protons)Neutrons N:139Isotopic mass:229.0317614(26) u (atomic weight of Thorium-229)Nuclide mass:228.9823956 u (calculated nuclear mass without electrons)Mass excess:29.58555 MeVMass defect:1.876914804 u (per nucleus)Nuclear binding energy:1748.33487844 MeV (per nucleus)
7.63465012 MeV (average binding energy per nucleon)Separation energy:S_N = 5.2567(26) MeV (first neutron)
S_P = 6.5981(28) MeV (first proton)Cross section:σ(n.γ) = 60 barn (thermal neutron capture cross-section)
σ(n.f) = 30 b (gap cross-section)Half-life:7880(120) aDecay constant λ:2.789324670261 × 10^-12 s^-1Specific activity α:7335242824.6334 Bq g^-1
0.19824980607117 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2+Magnetic dipole moment:μ(μ_N) = + 0.46(4)Charge radius:5.7557(143) femtometer fmYear of discovery:1947

Radioactive Decay

Half-life T_½ = 7880(120) a respectively 2.485 × 10¹¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²²⁵Ra	100 %	5.1676(10) MeV

Parent Nuclides

Direct parent isotopes are: ²³³U, ²²⁹Ac.

NMR data

Nuclear magnetic properties of the NMR active Nuclide ²²⁹Th

Isotope:²²⁹Th-NMRQuantity:Does not occur in nature!Spin:5/2+Nuclearmagnetic moment
μ/μ_N:+ 0.46(4)Gyromagnetic ratio γ:0.40 · 10⁷ rad T^-1 s^-1Nuclear g-factor:g_l = 0.184Quadrupole moment Q:3.110(6) barn (100 fm²)Line width parameter (factor):l = 30950.72 fm⁴Resonance frequency:v₀ = 1.40 at 1 TRelative Sensitivity:0.00042 (H₀ = const.)
0.3843 (v₀ = const.)
[related to ¹H = 1.000]

Nuclear Isomers

Nuclear isomers or excited states with the activation energy in keV related to the ground state.

Nuclear Isomer	Excitation Energy	Half-life	Spin
^229mTh	0.00810(17) keV	7(1) μs	3/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 139) and isobaric (same nucleon number A = 229) with Thorium-229. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 139	Isobar A = 229
83	²²²Bi
84	²²³Po
85	²²⁴At	²²⁹At
86	²²⁵Rn	²²⁹Rn
87	²²⁶Fr	²²⁹Fr
88	²²⁷Ra	²²⁹Ra
89	²²⁸Ac	²²⁹Ac
90	²²⁹Th	²²⁹Th
91	²³⁰Pa	²²⁹Pa
92	²³¹U	²²⁹U
93	²³²Np	²²⁹Np
94	²³³Pu	²²⁹Pu
95	²³⁴Am	²²⁹Am
96	²³⁵Cm
97	²³⁶Bk
98	²³⁷Cf

External data and identifiers

CAS:15594-54-4InChI Key:ZSLUVFAKFWKJRC-OIOBTWANSA-NSMILES:[229Th]PubChem:ID 167312Adopted Levels, Gammas:NuDat 229Th

Literature and References

[1] - Zsolt Varga, Adrian Nicholl, Klaus Mayer:
Determination of the ²²⁹Th half-life.
In: Physical Review C, (2014), DOI 10.1103/PhysRevC.89.064310.

[2] - NN:
Entwicklung einer Thoriumkern-Uhr Th-229.
In: Internetchemie News, (2015/2019).

[3] - Susan Hogle, Rose Ann Boll, Karen Murphy et. al:
Reactor production of Thorium-229.
In: Applied Radiation and Isotopes, (2016), DOI 10.1016/j.apradiso.2016.05.002.