Cerium-149

Properties and data of the isotope ¹⁴⁹Ce.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Cerium-149 is a radioisotope of the chemical element cerium, which has 91 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 149. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ¹⁴⁹Ce is exclusively for academic purposes.

According to a 1974 report, Cerium-149 was first indirectly identified during a study of short-lived fission products. A uranium target was irradiated with 14 MeV neutrons, producing the isotope as a product of a neutron-induced fission reaction. After rapid chemical separation, identification was achieved using a continuous solvent extraction process that allowed for selective enrichment of the cerium isotopes [1].

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

General data

Name of the isotope:Cerium-149; Ce-149Symbol:¹⁴⁹Ce or 14958CeMass number A:149 (= number of nucleons)Atomic number Z:58 (= number of protons)Neutrons N:91Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.5689655172414 (= neutron-proton ratio)Neutron excess (N-Z):33Isotopic mass:148.928427(11) u (atomic weight of Cerium-149)Nuclide mass:148.8966116 u (calculated nuclear mass without electrons)Mass excess:-66.66982 MeVMass defect:1.313932212 u (per nucleus)Nuclear binding energy:1223.91997188 MeV (per nucleus)
8.214228 MeV (average binding energy per nucleon)Separation energy:S_N = 4.343(15) MeV (first neutron)
S_P = 11.250(22) MeV (first proton)Half-life:5.12(25) sDecay constant λ:0.13538030870311 s^-1Specific activity α:5.508643842377 × 10⁺²⁰ Bq g^-1
14888226601.02 Ci g^-1Spin and parity:
(nuclear angular momentum)(3/2-)Year of discovery:1974

Radioactive Decay

Half-life T_½ = 5.12(25) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹⁴⁹Pr	100 %	4.369(14) MeV

Parent Nuclides

Direct parent isotope is: ¹⁴⁹La.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 91) and isobaric (same nucleon number A = 149) with Cerium-149. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 91	Isobar A = 149
52	¹⁴³Te
53	¹⁴⁴I
54	¹⁴⁵Xe
55	¹⁴⁶Cs	¹⁴⁹Cs
56	¹⁴⁷Ba	¹⁴⁹Ba
57	¹⁴⁸La	¹⁴⁹La
58	¹⁴⁹Ce	¹⁴⁹Ce
59	¹⁵⁰Pr	¹⁴⁹Pr
60	¹⁵¹Nd	¹⁴⁹Nd
61	¹⁵²Pm	¹⁴⁹Pm
62	¹⁵³Sm	¹⁴⁹Sm
63	¹⁵⁴Eu	¹⁴⁹Eu
64	¹⁵⁵Gd	¹⁴⁹Gd
65	¹⁵⁶Tb	¹⁴⁹Tb
66	¹⁵⁷Dy	¹⁴⁹Dy
67	¹⁵⁸Ho	¹⁴⁹Ho
68	¹⁵⁹Er	¹⁴⁹Er
69	¹⁶⁰Tm	¹⁴⁹Tm
70	¹⁶¹Yb	¹⁴⁹Yb
71	¹⁶²Lu	¹⁴⁹Lu
72	¹⁶³Hf
73	¹⁶⁴Ta
74	¹⁶⁵W
75	¹⁶⁶Re
76	¹⁶⁷Os
77	¹⁶⁸Ir
78	¹⁶⁹Pt
79	¹⁷⁰Au
80	¹⁷¹Hg

External data and identifiers

Adopted Levels, Gammas:NuDat 149Ce

Literature and References

[1] - P. O. Aronsson, G. Skarnemark, M. Skarestad:
Short-lived isotopes of lanthanum, cerium and praseodymium studied by SISAK-technique.
In: Journal of Inorganic and Nuclear Chemistry, 36, 8, (1974), DOI 10.1016/0022-1902(74)80494-X.