Promethium-139m
Properties and data of the isotope 139mPm.
See also: list of Promethium isotopes.
General data
Name of the isotope:Promethium-139m; Pm-139mSymbol:139mPm or 139m61PmMass number A:139 (= number of nucleons)Atomic number Z:61 (= number of protons)Neutrons N:78Isotopic mass:138.91680(15) u (atomic weight of Promethium-139m)
Excitation energy: 188.7(3) keVNuclide mass:138.8833392 u (calculated nuclear mass without electrons)Mass excess:-77.5003 MeVMass defect:1.2363904 u (per nucleus)Nuclear binding energy:1151.69023926 MeV (per nucleus)
8.28554129 MeV (average binding energy per nucleon)Half-life:0.18(2) sDecay constant λ:3.8508176697775 s-1Specific activity α:1.680446842995 × 10+22 Bq g-1
454174822431.14 Ci g-1Spin and parity:
(nuclear angular momentum)(11/2)-
Radioactive Decay
Half-life T½ = 0.18(2) s respectively 1.8 × 10-1 seconds s.
Decay mode | Daughter | Probability | Decay energy | γ energy (intensity) |
---|
EC/β+ | 139Nd | < 0.05 % | | |
Iso | 139Pm | & gt; 99.95 % | | |
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 |
---|
139Pm | | 4.15(5) min | (5/2)+ |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 78) and isobaric (same nucleon number A = 139) with Promethium-139m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
Z | Isotone N = 78 | Isobar A = 139 |
43 | 121Tc | |
44 | 122Ru | |
45 | 123Rh | |
46 | 124Pd | |
47 | 125Ag | |
48 | 126Cd | |
49 | 127In | |
50 | 128Sn | 139Sn |
51 | 129Sb | 139Sb |
52 | 130Te | 139Te |
53 | 131I | 139I |
54 | 132Xe | 139Xe |
55 | 133Cs | 139Cs |
56 | 134Ba | 139Ba |
57 | 135La | 139La |
58 | 136Ce | 139Ce |
59 | 137Pr | 139Pr |
60 | 138Nd | 139Nd |
61 | 139Pm | 139Pm |
62 | 140Sm | 139Sm |
63 | 141Eu | 139Eu |
64 | 142Gd | 139Gd |
65 | 143Tb | 139Tb |
66 | 144Dy | 139Dy |
67 | 145Ho | |
68 | 146Er | |
69 | 147Tm | |
70 | 148Yb | |
71 | 149Lu | |
External data and identifiers
Last update: 2020-10-20
Perma link: https://www.chemlin.org/isotope/promethium-139m
© 1996 - 2025 ChemLin