Cerium-138

Properties and data of the isotope ¹³⁸Ce.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Cerium-138 is a stable isotope of the chemical element cerium, which has 80 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 138.

Cerium-138 was first identified as a stable isotope in 1936. In mass spectrometric recordings of cerium ions produced from pure Cerium dioxide in a high-frequency spark discharge, weak lines appeared at 136 and 138 alongside the dominant lines at 140 and 142. This confirmed cerium-138 as one of the two rare, stable minor isotopes of the element cerium.

Natural cerium contains only 0.25 wt% ¹³⁸Ce. There are no practical applications for isotopically pure cerium-138.

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

General data

Name of the isotope:Cerium-138; Ce-138Symbol:¹³⁸Ce or 13858CeMass number A:138 (= number of nucleons)Atomic number Z:58 (= number of protons)Neutrons N:80Isotopic mass:137.90599(7) u (atomic weight of Cerium-138)Nuclide mass:137.8741746 u (calculated nuclear mass without electrons)Mass excess:-87.56975 MeVMass defect:1.241055136 u (per nucleus)Nuclear binding energy:1156.03541285 MeV (per nucleus)
8.37706821 MeV (average binding energy per nucleon)Separation energy:S_N = 9.7184(5) MeV (first neutron)
S_P = 7.7140(17) MeV (first proton)Half-life:stableSpin and parity:
(nuclear angular momentum)0+Charge radius:4.8737(18) femtometer fmYear of discovery:1936

Radioactive Decay

The cerium isotope with mass number 138 is generally considered stable. However, there is a theoretical possibility that this nuclide, with a half-life of approximately 4.4 × 10¹⁶ years, could decay radioactively to barium-138 via a double beta⁺ decay (β⁺β⁺).

Half-life T_½ = stable.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
2 β⁺	¹³⁸Ba	?

Parent Nuclides

Direct parent isotopes are: ¹³⁸Pr, ¹³⁸La.

Occurrence

Comparison of the natural Cerium isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):

	Atomic Mass m_a	Quantity	Half-life	Spin
Cerium Isotopic mixture	140.116 u	100 %
Isotope ¹⁴²Ce	141.90925(2) u	11.114(51) %	stable	0+
Isotope ¹⁴⁰Ce	139.90544(2) u	88.449(51) %	stable	0+
Isotope ¹³⁸Ce	137.90599(7) u	0.251(2) %	stable	0+
Isotope ¹³⁶Ce	135.907129(3) u	0.186(2) %	stable	0+

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
^138mCe	2129.28(12) keV	8.73(20) ms	7-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 80) and isobaric (same nucleon number A = 138) with Cerium-138. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 80	Isobar A = 138
44	¹²⁴Ru
45	¹²⁵Rh
46	¹²⁶Pd
47	¹²⁷Ag
48	¹²⁸Cd
49	¹²⁹In
50	¹³⁰Sn	¹³⁸Sn
51	¹³¹Sb	¹³⁸Sb
52	¹³²Te	¹³⁸Te
53	¹³³I	¹³⁸I
54	¹³⁴Xe	¹³⁸Xe
55	¹³⁵Cs	¹³⁸Cs
56	¹³⁶Ba	¹³⁸Ba
57	¹³⁷La	¹³⁸La
58	¹³⁸Ce	¹³⁸Ce
59	¹³⁹Pr	¹³⁸Pr
60	¹⁴⁰Nd	¹³⁸Nd
61	¹⁴¹Pm	¹³⁸Pm
62	¹⁴²Sm	¹³⁸Sm
63	¹⁴³Eu	¹³⁸Eu
64	¹⁴⁴Gd	¹³⁸Gd
65	¹⁴⁵Tb	¹³⁸Tb
66	¹⁴⁶Dy	¹³⁸Dy
67	¹⁴⁷Ho
68	¹⁴⁸Er
69	¹⁴⁹Tm
70	¹⁵⁰Yb
71	¹⁵¹Lu

External data and identifiers

Adopted Levels, Gammas:NuDat 138Ce

Literature and References

[1] - A. J. Dempster:
The Isotopic Constitution of Barium and Cerium.
In: Physical Review, 49, 947, (1936), DOI 10.1103/PhysRev.49.947.

[2] - P. Belli, R. Bernabei, R.S. Boiko et al.:
Search for double beta decay of ¹³⁶Ce and ¹³⁸Ce with HPGe gamma detector.
In: Nuclear Physics A, 930, 195-208, (2014), DOI 10.1016/j.nuclphysa.2014.08.072.

[3] - P. Belli, R. Bernabei, R.S. Boiko et al.:
New limits on 2ε, εβ⁺ and 2β⁺ decay of ¹³⁶Ce and ¹³⁸Ce with deeply purified cerium sample.
In: The European Physical Journal A, 53, 172, (2017), DOI 10.1140/epja/i2017-12360-0.