Gold-191

Properties and data of the isotope ¹⁹¹Au.

Content

General data

Name of the isotope:Gold-191; Au-191Symbol: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-191)Nuclide 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)Separation energy:S_N = 9.036(6) MeV (first neutron)
S_P = 3.780(5) MeV (first proton)Half-life:3.18(8) hDecay constant λ:6.054744763801 × 10^-5 s^-1Specific activity α:1.919080307293 × 10⁺¹⁷ Bq g^-1
5186703.5332254 Ci g^-1Spin and parity:
(nuclear angular momentum)3/2+Magnetic dipole moment:μ(μ_N) = + 0.1369(7)Quadrupole moment Q:+ 0.730(17) barn (100 fm²)Nuclear g-factor:g_l = 0.091266666666667Charge radius:5.4147(46) femtometer fmYear of discovery:1954

Radioactive Decay

Half-life T_½ = 3.18(8) h (hours) respectively 1.1448 × 10⁴ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹⁹¹Pt	100 %	1.900(6) MeV

Parent Nuclides

Direct parent isotope is: ¹⁹¹Hg.

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
^191mAu	266.2(7) keV	0.92(11) s	(11/2-)

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-191. 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