Iridium-191

Properties and data of the isotope ¹⁹¹Ir.

Contents

General Data

Parent Nuclides

NMR Data

Isotones und Isobares

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

General data

Name of the isotope:Iridium-191; Ir-191Symbol:¹⁹¹Ir or 19177IrMass number A:191 (= number of nucleons)Atomic number Z:77 (= number of protons)Neutrons N:114Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.4805194805195 (= neutron-proton ratio)Neutron excess (N-Z):37Isotopic mass:190.96059(2) u (atomic weight of Iridium-191)Nuclide mass:190.9183538 u (calculated nuclear mass without electrons)Mass excess:-36.71018 MeVMass defect:1.629737888 u (per nucleus)Nuclear binding energy:1518.09106424 MeV (per nucleus)
7.94812076 MeV (average binding energy per nucleon)Separation energy:S_N = 8.0265(4) MeV (first neutron)
S_P = 5.2900(11) MeV (first proton)Half-life:stableSpin and parity:
(nuclear angular momentum)3/2+Magnetic dipole moment:μ(μ_N) = + 0.1507(6)Charge radius:5.3968(1061) femtometer fmYear of discovery:1935

Parent Nuclides

Direct parent isotopes are: ¹⁹¹Os, ¹⁹¹Pt.

Occurrence

Comparison of the natural Iridium isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):

	Atomic Mass m_a	Quantity	Half-life	Spin
Iridium Isotopic mixture	192.217 u	100 %
Isotope ¹⁹¹Ir	190.96059(2) u	37.3(2) %	stable	3/2+
Isotope ¹⁹³Ir	192.96292(2) u	62.7(2) %	stable	3/2+

NMR data

Nuclear magnetic properties and parameters of the NMR active Nuclide ¹⁹¹Ir

Isotope:¹⁹¹Ir-NMRQuantity:37.3(2) %Spin:3/2+Nuclearmagnetic moment
μ/μ_N:+ 0.1507(6)Gyromagnetic ratio γ:0.4665 · 10⁷ rad T^-1 s^-1
0.74246 MHz T^-1Nuclear g-factor:g_l = 0.10046666666667Quadrupole moment Q:+0.816(9) barn (100 fm²)Line width parameter (factor):l = 8878.08 fm⁴Resonance frequency:v₀ = 0.7658 MHz at 1 TRelative Sensitivity:[related to ¹H = 1.000]:
0.00003 (H₀ = const.)
0.0899 (v₀ = const.)

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
^191m1Ir	171.29(4) keV	4.899(23) s	11/2-
^191m2Ir	2046.7+x keV	5.5(7) s

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 114) and isobaric (same nucleon number A = 191) with Iridium-191. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 114	Isobar A = 191
70	¹⁸⁴Yb
71	¹⁸⁵Lu
72	¹⁸⁶Hf
73	¹⁸⁷Ta	¹⁹¹Ta
74	¹⁸⁸W	¹⁹¹W
75	¹⁸⁹Re	¹⁹¹Re
76	¹⁹⁰Os	¹⁹¹Os
77	¹⁹¹Ir	¹⁹¹Ir
78	¹⁹²Pt	¹⁹¹Pt
79	¹⁹³Au	¹⁹¹Au
80	¹⁹⁴Hg	¹⁹¹Hg
81	¹⁹⁵Tl	¹⁹¹Tl
82	¹⁹⁶Pb	¹⁹¹Pb
83	¹⁹⁷Bi	¹⁹¹Bi
84	¹⁹⁸Po	¹⁹¹Po
85	¹⁹⁹At	¹⁹¹At
86	²⁰⁰Rn
87	²⁰¹Fr
88	²⁰²Ra
89	²⁰³Ac