Lanthanum-136m

Properties and data of the isotope ¹³⁶La.

Content

General data

Name of the isotope:Lanthanum-136m; La-136mSymbol:¹³⁶La or 13657LaMass number A:136 (= number of nucleons)Atomic number Z:57 (= number of protons)Neutrons N:79Isotopic mass:135.90763(6) u (atomic weight of Lanthanum-136m)
Excitation energy: 259.5(3) keVNuclide mass:135.8763631 u (calculated nuclear mass without electrons)Mass excess:-86.0421 MeVMass defect:1.222925188 u (per nucleus)Nuclear binding energy:1139.14747507 MeV (per nucleus)
8.37608438 MeV (average binding energy per nucleon)Half-life:114(5) msDecay constant λ:6.0802384259644 s^-1Specific activity α:2.712300167641 × 10⁺²² Bq g^-1
733054099362.51 Ci g^-1Spin and parity:
(nuclear angular momentum)(7-)

Radioactive Decay

Half-life T_½ = 114(5) ms respectively 1.14 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	¹³⁶La	100 %

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
¹³⁶La		9.87(3) min	1+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 79) and isobaric (same nucleon number A = 136) with Lanthanum-136m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 79	Isobar A = 136
44	¹²³Ru
45	¹²⁴Rh
46	¹²⁵Pd
47	¹²⁶Ag
48	¹²⁷Cd
49	¹²⁸In	¹³⁶In
50	¹²⁹Sn	¹³⁶Sn
51	¹³⁰Sb	¹³⁶Sb
52	¹³¹Te	¹³⁶Te
53	¹³²I	¹³⁶I
54	¹³³Xe	¹³⁶Xe
55	¹³⁴Cs	¹³⁶Cs
56	¹³⁵Ba	¹³⁶Ba
57	¹³⁶La	¹³⁶La
58	¹³⁷Ce	¹³⁶Ce
59	¹³⁸Pr	¹³⁶Pr
60	¹³⁹Nd	¹³⁶Nd
61	¹⁴⁰Pm	¹³⁶Pm
62	¹⁴¹Sm	¹³⁶Sm
63	¹⁴²Eu	¹³⁶Eu
64	¹⁴³Gd	¹³⁶Gd
65	¹⁴⁴Tb	¹³⁶Tb
66	¹⁴⁵Dy
67	¹⁴⁶Ho
68	¹⁴⁷Er
69	¹⁴⁸Tm
70	¹⁴⁹Yb
71	¹⁵⁰Lu