Cerium-139

Properties and data of the isotope ¹³⁹Ce.

Contents

General Data

Radioactive Decay

Parent Nuclides

NMR Data

Isotones und Isobares

Literature

Cerium-139 is a radioisotope of the chemical element cerium, which has 81 neutrons in its atomic nucleus in addition to the element-specific 58 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 139. This very short-lived, artificially produced, unstable and therefore radioactive nuclide has no practical medical or industrial significance; the study of ¹³⁹Ce serves exclusively academic purposes or as a reference radionuclide in calibration and detection experiments.

Cer-139 was first identified in 1948 when lanthanum was bombarded with 10 MeV deuterons (hydrogen-2 nuclei): ¹³⁹La(d,2n)¹³⁹Ce [1].

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

General data

Name of the isotope:Cerium-139; Ce-139Symbol:¹³⁹Ce or 13958CeMass number A:139 (= number of nucleons)Atomic number Z:58 (= number of protons)Neutrons N:81Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.3965517241379 (= neutron-proton ratio)Neutron excess (N-Z):23Isotopic mass:138.9066470(22) u (atomic weight of Cerium-139)Nuclide mass:138.8748316 u (calculated nuclear mass without electrons)Mass excess:-86.95776 MeVMass defect:1.249063052 u (per nucleus)Nuclear binding energy:1163.49473856 MeV (per nucleus)
8.37046575 MeV (average binding energy per nucleon)Separation energy:S_N = 7.4632(21) MeV (first neutron)
S_P = 7.7333(21) MeV (first proton)Half-life:137.642(22) dDecay constant λ:5.82906111460 × 10^-8 s^-1Specific activity α:2.543726602417 × 10⁺¹⁴ Bq g^-1
6874.9367632895 Ci g^-1Spin and parity:
(nuclear angular momentum)3/2+Magnetic dipole moment:μ(μ_N) = 1.06(4)Year of discovery:1948

Radioactive Decay

Half-life T_½ = 137.642(22) d respectively 1.1891232 × 10⁷ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC	¹³⁹La	100 %	0.2646(22) MeV	0.1658575(11) MeV 79.90(5) %

Parent Nuclides

Direct parent isotope is: ¹³⁹Pr.

NMR data

Nuclear magnetic properties and parameters of the NMR active Nuclide ¹³⁹Ce

Isotope:¹³⁹Ce-NMRQuantity:Does not occur in nature!Spin:3/2+Nuclearmagnetic moment
μ/μ_N:1.06(4)Nuclear g-factor:g_l = 0.70666666666667Quadrupole moment Q:0.02906 barn (100 fm²)Line width parameter (factor):l = 11.26 fm⁴Resonance frequency:v₀ = 5.39 MHz at 1 TRelative Sensitivity:[related to ¹H = 1.000]:
0.01012 (H₀ = const.)
0.6326 (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
^139mCe	754.24(8) keV	57.58(32) s	11/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 81) and isobaric (same nucleon number A = 139) with Cerium-139. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 81	Isobar A = 139
45	¹²⁶Rh
46	¹²⁷Pd
47	¹²⁸Ag
48	¹²⁹Cd
49	¹³⁰In
50	¹³¹Sn	¹³⁹Sn
51	¹³²Sb	¹³⁹Sb
52	¹³³Te	¹³⁹Te
53	¹³⁴I	¹³⁹I
54	¹³⁵Xe	¹³⁹Xe
55	¹³⁶Cs	¹³⁹Cs
56	¹³⁷Ba	¹³⁹Ba
57	¹³⁸La	¹³⁹La
58	¹³⁹Ce	¹³⁹Ce
59	¹⁴⁰Pr	¹³⁹Pr
60	¹⁴¹Nd	¹³⁹Nd
61	¹⁴²Pm	¹³⁹Pm
62	¹⁴³Sm	¹³⁹Sm
63	¹⁴⁴Eu	¹³⁹Eu
64	¹⁴⁵Gd	¹³⁹Gd
65	¹⁴⁶Tb	¹³⁹Tb
66	¹⁴⁷Dy	¹³⁹Dy
67	¹⁴⁸Ho
68	¹⁴⁹Er
69	¹⁵⁰Tm
70	¹⁵¹Yb
71	¹⁵²Lu
72	¹⁵³Hf