Samarium-136

Properties and data of the isotope ¹³⁶Sm.

Content

General data

Name of the isotope:Samarium-136; Sm-136Symbol:¹³⁶Sm or 13662SmMass number A:136 (= number of nucleons)Atomic number Z:62 (= number of protons)Neutrons N:74Isotopic mass:135.928276(13) u (atomic weight of Samarium-136)Nuclide mass:135.8942667 u (calculated nuclear mass without electrons)Mass excess:-66.81048 MeVMass defect:1.198079768 u (per nucleus)Nuclear binding energy:1116.00411541 MeV (per nucleus)
8.20591261 MeV (average binding energy per nucleon)Separation energy:S_N = 12.02(16) MeV (first neutron)
S_P = 4.05(8) MeV (first proton)Half-life:47(2) sDecay constant λ:0.014747812352339 s^-1Specific activity α:6.578770619385 × 10⁺¹⁹ Bq g^-1
1778046113.3474 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Year of discovery:1982

Radioactive Decay

Half-life T_½ = 47(2) s respectively 4.7 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹³⁶Pm	100 %	4.36(7) MeV

Parent Nuclides

Direct parent isotope is: ¹³⁶Eu.

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
^136mSm	2264.7(11) keV	15(1) μs	(8-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 74) and isobaric (same nucleon number A = 136) with Samarium-136. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 74	Isobar A = 136
41	¹¹⁵Nb
42	¹¹⁶Mo
43	¹¹⁷Tc
44	¹¹⁸Ru
45	¹¹⁹Rh
46	¹²⁰Pd
47	¹²¹Ag
48	¹²²Cd
49	¹²³In	¹³⁶In
50	¹²⁴Sn	¹³⁶Sn
51	¹²⁵Sb	¹³⁶Sb
52	¹²⁶Te	¹³⁶Te
53	¹²⁷I	¹³⁶I
54	¹²⁸Xe	¹³⁶Xe
55	¹²⁹Cs	¹³⁶Cs
56	¹³⁰Ba	¹³⁶Ba
57	¹³¹La	¹³⁶La
58	¹³²Ce	¹³⁶Ce
59	¹³³Pr	¹³⁶Pr
60	¹³⁴Nd	¹³⁶Nd
61	¹³⁵Pm	¹³⁶Pm
62	¹³⁶Sm	¹³⁶Sm
63	¹³⁷Eu	¹³⁶Eu
64	¹³⁸Gd	¹³⁶Gd
65	¹³⁹Tb	¹³⁶Tb
66	¹⁴⁰Dy
67	¹⁴¹Ho