See also: List of individual Osmium isotopes (and general data sources).
General data
Name of the isotope:Osmium-191; Os-191Symbol:191Os or 19176OsMass number A:191 (= number of nucleons)Atomic number Z:76 (= number of protons)Neutrons N:115Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.5131578947368 (= neutron-proton ratio)Neutron excess (N-Z):39Isotopic mass:190.9609282(7) u (atomic weight of Osmium-191)Nuclide mass:190.9192404 u (calculated nuclear mass without electrons)Mass excess:-36.39515 MeVMass defect:1.630239572 u (per nucleus)Nuclear binding energy:1518.55837988 MeV (per nucleus) 7.95056743 MeV (average binding energy per nucleon)Separation energy:SN = 5.75873(11) MeV (first neutron) SP = 8.05(7) MeV (first proton)Half-life:15.4(1) dDecay constant λ:5.209439488335 × 10-7 s-1Specific activity α:1.642847999073 × 10+15 Bq g-1 44401.297272254 Ci g-1Spin and parity: (nuclear angular momentum)9/2-Magnetic dipole moment:μ(μN) = + 0.96(3)Quadrupole moment Q:+2.53(16) barn (100 fm2)Nuclear g-factor:gl = 0.21333333333333Year of discovery:1940
Radioactive Decay
Half-life T½ = 15.4(1) d respectively 1.330560 × 106 seconds s.
Decay mode
Daughter
Probability
Decay energy
γ energy (intensity)
β-
191Ir
100 %
0.3136(11) MeV
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 = 115) and isobaric (same nucleon number A = 191) with Osmium-191. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
