Osmium-191

Properties and data of the isotope ¹⁹¹Os.

Contents

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:115Isotopic 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:S_N = 5.75873(11) MeV (first neutron)
S_P = 8.05(7) MeV (first proton)Half-life:15.4(1) dDecay constant λ:5.209439488335 × 10^-7 s^-1Specific activity α:1.651156757898 × 10⁺¹⁵ Bq g^-1
44625.858321581 Ci g^-1Spin and parity:
(nuclear angular momentum)9/2-Magnetic dipole moment:μ(μ_N) = + 0.96(3)Quadrupole moment Q:+ 2.53(16) barn (100 fm²)Nuclear g-factor:g_l = 0.21333333333333Year of discovery:1940

Radioactive Decay

Half-life T_½ = 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.

Nuclear Isomer	Excitation Energy	Half-life	Spin
^191mOs	74.382(3) keV	13.10(5) h	3/2-

Isotones and Isobars

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.

Z	Isotone N = 115	Isobar A = 191
70	¹⁸⁵Yb
71	¹⁸⁶Lu
72	¹⁸⁷Hf
73	¹⁸⁸Ta	¹⁹¹Ta
74	¹⁸⁹W	¹⁹¹W
75	¹⁹⁰Re	¹⁹¹Re
76	¹⁹¹Os	¹⁹¹Os
77	¹⁹²Ir	¹⁹¹Ir
78	¹⁹³Pt	¹⁹¹Pt
79	¹⁹⁴Au	¹⁹¹Au
80	¹⁹⁵Hg	¹⁹¹Hg
81	¹⁹⁶Tl	¹⁹¹Tl
82	¹⁹⁷Pb	¹⁹¹Pb
83	¹⁹⁸Bi	¹⁹¹Bi
84	¹⁹⁹Po	¹⁹¹Po
85	²⁰⁰At	¹⁹¹At
86	²⁰¹Rn
87	²⁰²Fr
88	²⁰³Ra
89	²⁰⁴Ac