Cerium-135

Properties and data of the isotope ¹³⁵Ce.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Cerium-135 is a radioisotope of the chemical element cerium, which has 77 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 135. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ¹³⁵Ce is exclusively for academic purposes.

¹³⁵Ce was first detected in 1948 when lanthanum oxide was irradiated with 60 MeV deuterons (hydrogen-2 nuclei) [1]: ¹³⁹La(d,6n)¹³⁹Ce.

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

General data

Name of the isotope:Cerium-135; Ce-135Symbol:¹³⁵Ce or 13558CeMass number A:135 (= number of nucleons)Atomic number Z:58 (= number of protons)Neutrons N:77Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.3275862068966 (= neutron-proton ratio)Neutron excess (N-Z):19Isotopic mass:134.909161(11) u (atomic weight of Cerium-135)Nuclide mass:134.8773456 u (calculated nuclear mass without electrons)Mass excess:-84.61598 MeVMass defect:1.211889388 u (per nucleus)Nuclear binding energy:1128.86769359 MeV (per nucleus)
8.36198292 MeV (average binding energy per nucleon)Separation energy:S_N = 7.855(23) MeV (first neutron)
S_P = 6.687(22) MeV (first proton)Half-life:17.7(3) hDecay constant λ:1.087801601632 × 10^-5 s^-1Specific activity α:4.888727218427 × 10⁺¹⁶ Bq g^-1
1321277.6266021 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2(+)Year of discovery:1948

Radioactive Decay

Half-life T_½ = 17.7(3) h (hours) respectively 6.3720 × 10⁴ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	¹³⁵La	100 %	2.027(14) MeV

Parent Nuclides

Direct parent isotope is: ¹³⁵Pr.

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
^135mCe	445.81(21) keV	20(1) s	(11/2-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 77) and isobaric (same nucleon number A = 135) with Cerium-135. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 77	Isobar A = 135
43	¹²⁰Tc
44	¹²¹Ru
45	¹²²Rh
46	¹²³Pd
47	¹²⁴Ag
48	¹²⁵Cd
49	¹²⁶In	¹³⁵In
50	¹²⁷Sn	¹³⁵Sn
51	¹²⁸Sb	¹³⁵Sb
52	¹²⁹Te	¹³⁵Te
53	¹³⁰I	¹³⁵I
54	¹³¹Xe	¹³⁵Xe
55	¹³²Cs	¹³⁵Cs
56	¹³³Ba	¹³⁵Ba
57	¹³⁴La	¹³⁵La
58	¹³⁵Ce	¹³⁵Ce
59	¹³⁶Pr	¹³⁵Pr
60	¹³⁷Nd	¹³⁵Nd
61	¹³⁸Pm	¹³⁵Pm
62	¹³⁹Sm	¹³⁵Sm
63	¹⁴⁰Eu	¹³⁵Eu
64	¹⁴¹Gd	¹³⁵Gd
65	¹⁴²Tb	¹³⁵Tb
66	¹⁴³Dy
67	¹⁴⁴Ho
68	¹⁴⁵Er
69	¹⁴⁶Tm

External data and identifiers

Adopted Levels, Gammas:NuDat 135Ce

Literature and References

[1] - J. B. Chubbuck and I. Perlman:
Neutron Deficient Isotopes of Cerium and Lanthanum.
In: Physical Review, 74, 982, (1948), DOI 10.1103/PhysRev.74.982.2.