Promethium-135m
Properties and data of the isotope 135mPm.
See also: list of Promethium isotopes.
General data
Name of the isotope:Promethium-135m; Pm-135mSymbol:135mPm or 135m61PmMass number A:135 (= number of nucleons)Atomic number Z:61 (= number of protons)Neutrons N:74Isotopic mass:134.92480(8) u (atomic weight of Promethium-135m)
Excitation energy: 68.7+y keVNuclide mass:134.8913392 u (calculated nuclear mass without electrons)Mass excess:-70.04835 MeVMass defect:1.193730736 u (per nucleus)Nuclear binding energy:1111.9530182 MeV (per nucleus)
8.23668902 MeV (average binding energy per nucleon)Half-life:45(4) sDecay constant λ:0.01540327067911 s-1Specific activity α:6.922437741293 × 10+19 Bq g-1
1870929119.2685 Ci g-1Spin and parity:
(nuclear angular momentum)(11/2-)
Radioactive Decay
Half-life T½ = 45(4) s respectively 4.5 × 101 seconds s.
Decay mode | Daughter | Probability | Decay energy | γ energy (intensity) |
---|
EC/β+ | 135Nd | 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 |
---|
135Pm | | 49(3) s | (5/2+,3/2+) |
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 74) and isobaric (same nucleon number A = 135) with Promethium-135m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
Z | Isotone N = 74 | Isobar A = 135 |
41 | 115Nb | |
42 | 116Mo | |
43 | 117Tc | |
44 | 118Ru | |
45 | 119Rh | |
46 | 120Pd | |
47 | 121Ag | |
48 | 122Cd | |
49 | 123In | 135In |
50 | 124Sn | 135Sn |
51 | 125Sb | 135Sb |
52 | 126Te | 135Te |
53 | 127I | 135I |
54 | 128Xe | 135Xe |
55 | 129Cs | 135Cs |
56 | 130Ba | 135Ba |
57 | 131La | 135La |
58 | 132Ce | 135Ce |
59 | 133Pr | 135Pr |
60 | 134Nd | 135Nd |
61 | 135Pm | 135Pm |
62 | 136Sm | 135Sm |
63 | 137Eu | 135Eu |
64 | 138Gd | 135Gd |
65 | 139Tb | 135Tb |
66 | 140Dy | |
67 | 141Ho | |
External data and identifiers
Last update: 2020-10-20
Perma link: https://www.chemlin.org/isotope/promethium-135m
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