Promethium-137

Properties and data of the isotope ¹³⁷Pm.

Content

General data

Name of the isotope:Promethium-137; Pm-137Symbol:¹³⁷Pm or 13761PmMass number A:137 (= number of nucleons)Atomic number Z:61 (= number of protons)Neutrons N:76Isotopic mass:136.920480(14) u (atomic weight of Promethium-137)Nuclide mass:136.8870192 u (calculated nuclear mass without electrons)Mass excess:-74.0724 MeVMass defect:1.215380568 u (per nucleus)Nuclear binding energy:1132.11970681 MeV (per nucleus)
8.26364749 MeV (average binding energy per nucleon)Separation energy:S_N = 10.97(7) MeV (first neutron)
S_P = 2.163(18) MeV (first proton)Half-life:2.4(1) minDecay constant λ:0.0048135220872218 s^-1Specific activity α:2.131449120710 × 10⁺¹⁹ Bq g^-1
576067329.92184 Ci g^-1Spin and parity:
(nuclear angular momentum)11/2-Year of discovery:1975

Radioactive Decay

Half-life T_½ = 2.4(1) min (minutes) respectively 1.44 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹³⁷Nd	100 %	5.512(18) MeV

Parent Nuclides

Direct parent isotope is: ¹³⁷Sm.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 76) and isobaric (same nucleon number A = 137) with Promethium-137. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 76	Isobar A = 137
42	¹¹⁸Mo
43	¹¹⁹Tc
44	¹²⁰Ru
45	¹²¹Rh
46	¹²²Pd
47	¹²³Ag
48	¹²⁴Cd
49	¹²⁵In	¹³⁷In
50	¹²⁶Sn	¹³⁷Sn
51	¹²⁷Sb	¹³⁷Sb
52	¹²⁸Te	¹³⁷Te
53	¹²⁹I	¹³⁷I
54	¹³⁰Xe	¹³⁷Xe
55	¹³¹Cs	¹³⁷Cs
56	¹³²Ba	¹³⁷Ba
57	¹³³La	¹³⁷La
58	¹³⁴Ce	¹³⁷Ce
59	¹³⁵Pr	¹³⁷Pr
60	¹³⁶Nd	¹³⁷Nd
61	¹³⁷Pm	¹³⁷Pm
62	¹³⁸Sm	¹³⁷Sm
63	¹³⁹Eu	¹³⁷Eu
64	¹⁴⁰Gd	¹³⁷Gd
65	¹⁴¹Tb	¹³⁷Tb
66	¹⁴²Dy
67	¹⁴³Ho
68	¹⁴⁴Er
69	¹⁴⁵Tm