Iridium-166

Properties and data of the isotope ¹⁶⁶Ir.

Contents

See also: List of individual Iridium isotopes (and general data sources).

General data

Name of the isotope:Iridium-166; Ir-166Symbol:¹⁶⁶Ir or 16677IrMass number A:166 (= number of nucleons)Atomic number Z:77 (= number of protons)Neutrons N:89Isotopic mass:165.98566(21) u (atomic weight of Iridium-166)Nuclide mass:165.9434238 u (calculated nuclear mass without electrons)Mass excess:-13.35762 MeVMass defect:1.388044988 u (per nucleus)Nuclear binding energy:1292.95557805 MeV (per nucleus)
7.78888902 MeV (average binding energy per nucleon)Separation energy:S_N = 9.83(25) MeV (first neutron)
S_P = -1.152(8) MeV (first proton)Half-life:10.5(22) msDecay constant λ:66.014017196185 s^-1Specific activity α:2.409367941125 × 10⁺²³ Bq g^-1
6511805246285.1 Ci g^-1Spin and parity:
(nuclear angular momentum)(2-)Year of discovery:1981

Radioactive Decay

Half-life T_½ = 10.5(22) ms respectively 1.05 × 10^-2 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	¹⁶²Re	93(3) %	6.722(6) MeV
p	¹⁶⁵Os	7(3) %

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
^166mIr	172(6) keV	15.1(9) ms	(9+)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 89) and isobaric (same nucleon number A = 166) with Iridium-166. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 89	Isobar A = 166
50	¹³⁹Sn
51	¹⁴⁰Sb
52	¹⁴¹Te
53	¹⁴²I
54	¹⁴³Xe
55	¹⁴⁴Cs
56	¹⁴⁵Ba
57	¹⁴⁶La
58	¹⁴⁷Ce
59	¹⁴⁸Pr
60	¹⁴⁹Nd
61	¹⁵⁰Pm
62	¹⁵¹Sm	¹⁶⁶Sm
63	¹⁵²Eu	¹⁶⁶Eu
64	¹⁵³Gd	¹⁶⁶Gd
65	¹⁵⁴Tb	¹⁶⁶Tb
66	¹⁵⁵Dy	¹⁶⁶Dy
67	¹⁵⁶Ho	¹⁶⁶Ho
68	¹⁵⁷Er	¹⁶⁶Er
69	¹⁵⁸Tm	¹⁶⁶Tm
70	¹⁵⁹Yb	¹⁶⁶Yb
71	¹⁶⁰Lu	¹⁶⁶Lu
72	¹⁶¹Hf	¹⁶⁶Hf
73	¹⁶²Ta	¹⁶⁶Ta
74	¹⁶³W	¹⁶⁶W
75	¹⁶⁴Re	¹⁶⁶Re
76	¹⁶⁵Os	¹⁶⁶Os
77	¹⁶⁶Ir	¹⁶⁶Ir
78	¹⁶⁷Pt	¹⁶⁶Pt