See also: List of individual Osmium isotopes (and general data sources).
General data
Name of the isotope:Osmium-181m; Os-181mSymbol:181mOs or 181m76OsMass number A:181 (= number of nucleons)Atomic number Z:76 (= number of protons)Neutrons N:105Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.3815789473684 (= neutron-proton ratio)Neutron excess (N-Z):29Excitation energy:49.20(14) keVIsotopic mass:180.953247(27) u (atomic weight of Osmium-181m)Nuclide mass:180.9115592 u (calculated nuclear mass without electrons)Mass excess:-43.55014 MeVMass defect:1.551271612 u (per nucleus)Nuclear binding energy:1445.00019895 MeV (per nucleus) 7.98342651 MeV (average binding energy per nucleon)Half-life:2.7(1) minDecay constant λ:0.0042786862997527 s-1Specific activity α:1.42395074927 × 10+19 Bq g-1 384851553.85892 Ci g-1Spin and parity: (nuclear angular momentum)7/2-
Radioactive Decay
Half-life T½ = 2.7(1) min (minutes) respectively 1.62 × 102 seconds s.
Decay mode
Daughter
Probability
Decay energy
γ energy (intensity)
EC/β+
181Re
ca. 97 %
Iso
181Os
≤ 3 %
Nuclear Isomers
Nuclear isomers or excited states with the activation energy in keV related to the ground state.
The following table shows the atomic nuclei that are isotonic (same neutron number N = 105) and isobaric (same nucleon number A = 181) with Osmium-181m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
