Gold-187m

Properties and data of the isotope ¹⁸⁷Au.

Content

General data

Name of the isotope:Gold-187m; Au-187mSymbol:¹⁸⁷Au or 18779AuMass number A:187 (= number of nucleons)Atomic number Z:79 (= number of protons)Neutrons N:108Isotopic mass:186.964543(24) u (atomic weight of Gold-187m)
Excitation energy: 120.33(14) keVNuclide mass:186.9212099 u (calculated nuclear mass without electrons)Mass excess:-33.02798 MeVMass defect:1.589445456 u (per nucleus)Nuclear binding energy:1480.55890559 MeV (per nucleus)
7.9174273 MeV (average binding energy per nucleon)Half-life:2.3(1) sDecay constant λ:0.30136833937389 s^-1Specific activity α:9.757433281907 × 10⁺²⁰ Bq g^-1
26371441302.452 Ci g^-1Spin and parity:
(nuclear angular momentum)9/2(-)

Radioactive Decay

Half-life T_½ = 2.3(1) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	¹⁸⁷Au	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
¹⁸⁷Au		8.3(2) min	1/2(+)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 108) and isobaric (same nucleon number A = 187) with Gold-187m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 108	Isobar A = 187
66	¹⁷⁴Dy
67	¹⁷⁵Ho
68	¹⁷⁶Er
69	¹⁷⁷Tm
70	¹⁷⁸Yb
71	¹⁷⁹Lu	¹⁸⁷Lu
72	¹⁸⁰Hf	¹⁸⁷Hf
73	¹⁸¹Ta	¹⁸⁷Ta
74	¹⁸²W	¹⁸⁷W
75	¹⁸³Re	¹⁸⁷Re
76	¹⁸⁴Os	¹⁸⁷Os
77	¹⁸⁵Ir	¹⁸⁷Ir
78	¹⁸⁶Pt	¹⁸⁷Pt
79	¹⁸⁷Au	¹⁸⁷Au
80	¹⁸⁸Hg	¹⁸⁷Hg
81	¹⁸⁹Tl	¹⁸⁷Tl
82	¹⁹⁰Pb	¹⁸⁷Pb
83	¹⁹¹Bi	¹⁸⁷Bi
84	¹⁹²Po	¹⁸⁷Po
85	¹⁹³At
86	¹⁹⁴Rn