Cerium-136

Properties and data of the isotope ¹³⁶Ce.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Cerium-136 is a stable isotope of the chemical element cerium, which has 78 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 136.

Cerium-136 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 in addition to the dominant lines at 140 and 142. This confirmed Cerium-136 as the rarest (natural proportion of only about 0.19%) of the four stable cerium isotopes.

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

General data

Name of the isotope:Cerium-136; Ce-136Symbol:¹³⁶Ce or 13658CeMass number A:136 (= number of nucleons)Atomic number Z:58 (= number of protons)Neutrons N:78Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):1.3448275862069 (= neutron-proton ratio)Neutron excess (N-Z):20Isotopic mass:135.907129(3) u (atomic weight of Cerium-136)Nuclide mass:135.8753136 u (calculated nuclear mass without electrons)Mass excess:-86.50878 MeVMass defect:1.222586304 u (per nucleus)Nuclear binding energy:1138.83180666 MeV (per nucleus)
8.37376328 MeV (average binding energy per nucleon)Separation energy:S_N = 9.964(10) MeV (first neutron)
S_P = 7.154(9) MeV (first proton)Half-life:stableSpin and parity:
(nuclear angular momentum)0+Charge radius:4.8739(18) femtometer fmYear of discovery:1936

Radioactive Decay

The cerium isotope with mass number 136 is considered stable. Theoretically, however, it is possible that the nuclide decays to barium-136 in a double beta decay (2β⁺) with a half-life of 3.2 × 10¹⁶ years; this radioactive decay has not yet been observed.

Half-life T_½ = stable.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
2 β⁺	¹³⁶Ba	?

Parent Nuclides

Direct parent isotope is: ¹³⁶Pr.

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
^136mCe	3095.0(6) keV	1.96(9) μs	10+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 78) and isobaric (same nucleon number A = 136) with Cerium-136. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 78	Isobar A = 136
43	¹²¹Tc
44	¹²²Ru
45	¹²³Rh
46	¹²⁴Pd
47	¹²⁵Ag
48	¹²⁶Cd
49	¹²⁷In	¹³⁶In
50	¹²⁸Sn	¹³⁶Sn
51	¹²⁹Sb	¹³⁶Sb
52	¹³⁰Te	¹³⁶Te
53	¹³¹I	¹³⁶I
54	¹³²Xe	¹³⁶Xe
55	¹³³Cs	¹³⁶Cs
56	¹³⁴Ba	¹³⁶Ba
57	¹³⁵La	¹³⁶La
58	¹³⁶Ce	¹³⁶Ce
59	¹³⁷Pr	¹³⁶Pr
60	¹³⁸Nd	¹³⁶Nd
61	¹³⁹Pm	¹³⁶Pm
62	¹⁴⁰Sm	¹³⁶Sm
63	¹⁴¹Eu	¹³⁶Eu
64	¹⁴²Gd	¹³⁶Gd
65	¹⁴³Tb	¹³⁶Tb
66	¹⁴⁴Dy
67	¹⁴⁵Ho
68	¹⁴⁶Er
69	¹⁴⁷Tm
70	¹⁴⁸Yb
71	¹⁴⁹Lu

External data and identifiers

Adopted Levels, Gammas:NuDat 136Ce

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.