Iridium-197

Properties and data of the isotope ¹⁹⁷Ir.

Content

General data

Name of the isotope:Iridium-197; Ir-197Symbol:¹⁹⁷Ir or 19777IrMass number A:197 (= number of nucleons)Atomic number Z:77 (= number of protons)Neutrons N:120Isotopic mass:196.969657(22) u (atomic weight of Iridium-197)Nuclide mass:196.9274208 u (calculated nuclear mass without electrons)Mass excess:-28.26432 MeVMass defect:1.672660384 u (per nucleus)Nuclear binding energy:1558.07311173 MeV (per nucleus)
7.90900057 MeV (average binding energy per nucleon)Separation energy:S_N = 6.90(4) MeV (first neutron)
S_P = 7.28(4) MeV (first proton)Half-life:5.8(5) minDecay constant λ:0.0019918022429883 s^-1Specific activity α:6.119853914496 × 10⁺¹⁸ Bq g^-1
165401457.14856 Ci g^-1Spin and parity:
(nuclear angular momentum)3/2+Year of discovery:1952

Radioactive Decay

Half-life T_½ = 5.8(5) min (minutes) respectively 3.48 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹⁹⁷Pt	100 %	2.156(20) 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
^197mIr	115(5) keV	8.9(3) min	11/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 120) and isobaric (same nucleon number A = 197) with Iridium-197. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 120	Isobar A = 197
73	¹⁹³Ta
74	¹⁹⁴W	¹⁹⁷W
75	¹⁹⁵Re	¹⁹⁷Re
76	¹⁹⁶Os	¹⁹⁷Os
77	¹⁹⁷Ir	¹⁹⁷Ir
78	¹⁹⁸Pt	¹⁹⁷Pt
79	¹⁹⁹Au	¹⁹⁷Au
80	²⁰⁰Hg	¹⁹⁷Hg
81	²⁰¹Tl	¹⁹⁷Tl
82	²⁰²Pb	¹⁹⁷Pb
83	²⁰³Bi	¹⁹⁷Bi
84	²⁰⁴Po	¹⁹⁷Po
85	²⁰⁵At	¹⁹⁷At
86	²⁰⁶Rn	¹⁹⁷Rn
87	²⁰⁷Fr
88	²⁰⁸Ra
89	²⁰⁹Ac
90	²¹⁰Th