Gold-191m

Properties and data of the isotope ¹⁹¹Au.

Content

General data

Name of the isotope:Gold-191m; Au-191mSymbol:¹⁹¹Au or 19179AuMass number A:191 (= number of nucleons)Atomic number Z:79 (= number of protons)Neutrons N:112Isotopic mass:190.963716(5) u (atomic weight of Gold-191m)
Excitation energy: 266.2(7) keVNuclide mass:190.9203829 u (calculated nuclear mass without electrons)Mass excess:-33.79833 MeVMass defect:1.62493212 u (per nucleus)Nuclear binding energy:1513.61452019 MeV (per nucleus)
7.92468335 MeV (average binding energy per nucleon)Half-life:0.92(11) sDecay constant λ:0.75342084843472 s^-1Specific activity α:2.388003408466 × 10⁺²¹ Bq g^-1
64540632661.265 Ci g^-1Spin and parity:
(nuclear angular momentum)(11/2-)Magnetic dipole moment:μ(μ_N) = 6.6(6)Nuclear g-factor:g_l = 1.2

Radioactive Decay

Half-life T_½ = 0.92(11) s respectively 9.2 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	¹⁹¹Au	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
¹⁹¹Au		3.18(8) h	3/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 112) and isobaric (same nucleon number A = 191) with Gold-191m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 112	Isobar A = 191
70	¹⁸²Yb
71	¹⁸³Lu
72	¹⁸⁴Hf
73	¹⁸⁵Ta	¹⁹¹Ta
74	¹⁸⁶W	¹⁹¹W
75	¹⁸⁷Re	¹⁹¹Re
76	¹⁸⁸Os	¹⁹¹Os
77	¹⁸⁹Ir	¹⁹¹Ir
78	¹⁹⁰Pt	¹⁹¹Pt
79	¹⁹¹Au	¹⁹¹Au
80	¹⁹²Hg	¹⁹¹Hg
81	¹⁹³Tl	¹⁹¹Tl
82	¹⁹⁴Pb	¹⁹¹Pb
83	¹⁹⁵Bi	¹⁹¹Bi
84	¹⁹⁶Po	¹⁹¹Po
85	¹⁹⁷At	¹⁹¹At
86	¹⁹⁸Rn
87	¹⁹⁹Fr