Promethium-136m

Properties and data of the isotope ¹³⁶Pm.

Content

General data

Name of the isotope:Promethium-136m; Pm-136mSymbol:¹³⁶Pm or 13661PmMass number A:136 (= number of nucleons)Atomic number Z:61 (= number of protons)Neutrons N:75Isotopic mass:135.92360(7) u (atomic weight of Promethium-136m)
Excitation energy: XNuclide mass:135.8901392 u (calculated nuclear mass without electrons)Mass excess:-71.16614 MeVMass defect:1.203595652 u (per nucleus)Nuclear binding energy:1121.14212826 MeV (per nucleus)
8.24369212 MeV (average binding energy per nucleon)Half-life:300(50) sDecay constant λ:0.0023104906018665 s^-1Specific activity α:1.030674063703 × 10⁺¹⁹ Bq g^-1
278560557.75776 Ci g^-1Spin and parity:
(nuclear angular momentum)(2)

Radioactive Decay

Half-life T_½ = 300(50) s respectively 3.00 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹³⁶Nd	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
¹³⁶Pm	Y	107(6) s	(5-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 75) and isobaric (same nucleon number A = 136) with Promethium-136m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 75	Isobar A = 136
42	¹¹⁷Mo
43	¹¹⁸Tc
44	¹¹⁹Ru
45	¹²⁰Rh
46	¹²¹Pd
47	¹²²Ag
48	¹²³Cd
49	¹²⁴In	¹³⁶In
50	¹²⁵Sn	¹³⁶Sn
51	¹²⁶Sb	¹³⁶Sb
52	¹²⁷Te	¹³⁶Te
53	¹²⁸I	¹³⁶I
54	¹²⁹Xe	¹³⁶Xe
55	¹³⁰Cs	¹³⁶Cs
56	¹³¹Ba	¹³⁶Ba
57	¹³²La	¹³⁶La
58	¹³³Ce	¹³⁶Ce
59	¹³⁴Pr	¹³⁶Pr
60	¹³⁵Nd	¹³⁶Nd
61	¹³⁶Pm	¹³⁶Pm
62	¹³⁷Sm	¹³⁶Sm
63	¹³⁸Eu	¹³⁶Eu
64	¹³⁹Gd	¹³⁶Gd
65	¹⁴⁰Tb	¹³⁶Tb
66	¹⁴¹Dy
67	¹⁴²Ho
68	¹⁴³Er
69	¹⁴⁴Tm