Plutonium-239

Properties and data of the isotope ²³⁹Pu.

Contents

General Data

Radioactive Decay

Parent Nuclides

Formation

NMR Data

Isotones und Isobares

Plutonium-239 is the radioisotope of the element plutonium, whose atomic nucleus has 145 neutrons in addition to the element-specific 94 protons, resulting in a mass number of 239: ²³⁹ Pu.

See also: List of individual Plutonium isotopes (and general data sources).

General data

Name of the isotope:Plutonium-239; Pu-239Symbol:²³⁹Pu or 23994PuMass number A:239 (= number of nucleons)Atomic number Z:94 (= number of protons)Neutrons N:145Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.5425531914894 (= neutron-proton ratio)Neutron excess (N-Z):51Isotopic mass:239.0521617(12) u (atomic weight of Plutonium-239)Nuclide mass:239.0006022 u (calculated nuclear mass without electrons)Mass excess:48.58831 MeVMass defect:1.939804128 u (per nucleus)Nuclear binding energy:1806.91590641 MeV (per nucleus)
7.5603176 MeV (average binding energy per nucleon)Separation energy:S_N = 5.6462(3) MeV (first neutron)
S_P = 6.1553(4) MeV (first proton)Half-life:24110(30) aDecay constant λ:9.116363232425 × 10^-13 s^-1Specific activity α:2297072113.6407 Bq g^-1
0.062083030098397 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2+Magnetic dipole moment:μ(μ_N) = + 0.203(4)Charge radius:5.8601(378) femtometer fmYear of discovery:1946

Radioactive Decay

Half-life T_½ = 24110(30) a respectively 7.60333 × 10¹¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²³⁵U	ca. 100 %	5.24452(21) MeV
SZ	^div	trace

Parent Nuclides

Direct parent isotopes are: ²³⁹Am, ²³⁹Np, ²⁴³Cm.

Formation

The nuclide practically does not occur in nature. Plutonium-239 is produced in nuclear reactors by transmutation from uranium-238.

NMR data

Nuclear magnetic properties and parameters of the NMR active Nuclide ²³⁹Pu

Isotope:²³⁹Pu-NMRQuantity:Does not occur in nature!Spin:1/2+Nuclearmagnetic moment
μ/μ_N:+ 0.203(4)Gyromagnetic ratio γ:0.972 · 10⁷ rad T^-1 s^-1
1.54699 MHz T^-1Nuclear g-factor:g_l = 0.406Resonance frequency:v₀ = 3.09 MHz at 1 TRelative Sensitivity:[related to ¹H = 1.000]:
0.00038 (H₀ = const.)
0.0727 (v₀ = const.)

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
^239m1Pu	391.584(3) keV	193(4) ns	7/2-
^239m2Pu	3100 keV	7.5(10) μs	(5/2+)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 145) and isobaric (same nucleon number A = 239) with Plutonium-239. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 145	Isobar A = 239
87	²³²Fr
88	²³³Ra
89	²³⁴Ac
90	²³⁵Th
91	²³⁶Pa	²³⁹Pa
92	²³⁷U	²³⁹U
93	²³⁸Np	²³⁹Np
94	²³⁹Pu	²³⁹Pu
95	²⁴⁰Am	²³⁹Am
96	²⁴¹Cm	²³⁹Cm
97	²⁴²Bk	²³⁹Bk
98	²⁴³Cf	²³⁹Cf
99	²⁴⁴Es
100	²⁴⁵Fm
101	²⁴⁶Md