Isotopes of iridium

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There are two natural isotopes of iridium (77Ir), 191Ir and 193Ir, both stable. In addition, there are 40 known radioisotopes with mass numbers 164 through 205, the most stable being 192Ir with a half-life of 73.82 days, and many nuclear isomers, the most stable of which is 192m2Ir with a half-life of 241 years. All other nuclides have half-lives under two weeks, most under a day. All isotopes of iridium are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed.[4]

Quick facts Main isotopes, Decay ...
Isotopes of iridium (77Ir)
Main isotopes[1] Decay
Isotope abun­dance half-life (t1/2) mode pro­duct
189Ir synth 13.2 d ε 189Os
190Ir synth 11.751 d ε 190Os
191Ir 37.3% stable
192Ir synth 73.82 d β− 192Pt
ε 192Os
192m2Ir synth 241 y IT 192Ir
193Ir 62.7% stable
Standard atomic weight Ar°(Ir)
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The isotope 191Ir was the first one of any element to be shown to present a Mössbauer effect. This renders it useful for Mössbauer spectroscopy for research in physics, chemistry, biochemistry, metallurgy, and mineralogy.[5]

List of isotopes


More information Nuclide, Z ...
Nuclide
[n 1]		 Z N Isotopic mass (Da)[6]
[n 2][n 3]		 Discovery
year[7][8]		 Half-life[1]
[n 4]		 Decay
mode[1]
[n 5]		 Daughter
isotope
[n 6][n 7]		 Spin and
parity[1]
[n 8][n 4]		 Natural abundance (mole fraction)
Excitation energy[n 4] Normal proportion[1] Range of variation
164Ir[n 9][9] 77 87 163.99197#(34) 2014 <0.5 μs p? 163Os 2#
164mIr 260(100) keV 2014 70(10) μs p (96%) 163Os (9+)
α (4%) 160mRe
165Ir 77 88 165.98572#(22) 1997 1.20+0.82
−0.74 μs[10]		 p 164Os (1/2+)
165mIr[9] ~255 keV 1997 340(40) μs p (88%) 164Os (11/2)
α (12%) 161mRe
166Ir 77 89 165.98582#(22) 1981 10.5(22) ms α (93%) 162Re (2)
p (7%) 165Os
166mIr 171(6) keV 1997 15.1(9) ms α (98.2%) 162Re (9)+
p (1.8%) 165Os
167Ir 77 90 166.981672(20) 1981 29.3(6) ms α (43.5%) 163Re 1/2+
p (38.6%) 166Os
β+ (17.9%) 167Os
167mIr 175.5(21) keV 1997 28.5(5) ms α (89%) 163Re 11/2
β+ (11%) 167Os
p (0.41%) 166Os
168Ir 77 91 167.979961(59) 1978 230(50) ms α 164Re (2)-
168mIr[n 10] 40(250) keV 1996 163(16) ms α (77%) 164Re (9,10)+
β+? 168Os
β+, p? 167Re
169Ir 77 92 168.976282(25) 1978 353(4) ms α (53%) 165Re (1/2+)
β+ (47%) 169Os
169mIr 153(22) keV 1999 280(1) ms α (79%) 165Re (11/2)
β+? 169Os
p? 168Os
170Ir 77 93 169.97511#(11) 1977 910(150) ms β+ (94.8%) 170Os (3)
α (5.2%) 166Re
170mIr[n 10] 40(50)#keV 2002 811(18) ms α (38%) 166Re (8+)
β+? 170Os
IT? 170Ir
171Ir 77 94 170.971646(41) 1967 3.1(3) s β+ (85%) 171Os 1/2+
α (15%) 167Re
171mIr 164(11)#keV 2002 1.47(6) s α (54%) 167Re (11/2)
β+? 171Os
p? 170Os
172Ir 77 95 171.970607(35) 1967 4.4(3) s β+ (~98%) 172Os (3,4)
α (~2%) 168Re
172mIr 139(10) keV 1992 2.19(7) s β+ (90.5%) 172Os (7+)
α (9.5%) 168Re
173Ir 77 96 172.967505(11) 1967 9.0(8) s β+ (96.5%) 173Os (1/2+,3/2+)
α (3.5%) 169Re
173mIr 226(9) keV 1992 2.20(5) s β+ (88%) 173Os 11/2
α (12%) 169Re
174Ir 77 97 173.966950(12) 1967 7.9(6) s β+ (99.5%) 174Os (2+,3)
α (0.5%) 170Re
174mIr 124(16) keV 1992 4.9(3) s β+ (97.5%) 174Os (6,7,8,9)
α (2.5%) 170Re
175Ir 77 98 174.964150(13) 1967 9(2) s β+ (99.15%) 175Os (1/2+)
α (0.85%) 171Re
175m1Ir 50(40) keV 2010 33(4) s β+ 175Os 9/2#
175m2Ir 97.4(7) keV 2019 6.58(15) μs IT 175Ir (5/2)
176Ir 77 99 175.9636263(87) 1967 8.7(5) s β+ (96.9%) 176Os (3+)
α (3.1%) 172Re
177Ir 77 100 176.961302(21) 1967 29.8(17) s β+ (99.94%) 177Os 5/2
α (0.06%) 173Re
177mIr 180.9(4) keV (1991)[n 11] >100 ns IT 177Ir (5/2+)
178Ir 77 101 177.961079(20) 1972 12(2) s β+ 178Os 3+#
179Ir 77 102 178.959118(10) 1992 79(1) s β+ 179Os (5/2)
180Ir 77 103 179.959229(23) 1972 1.5(1) min β+ 180Os (5+)
181Ir 77 104 180.9576347(56) 1972 4.90(15) min β+ 181Os 5/2
181m1Ir 289.33(13) keV 1992 298 ns IT 181Ir 5/2+
181m2Ir 366.30(22) keV 1990 126(6) ns IT 181Ir 9/2
182Ir 77 105 181.958076(23) 1961 15.0(10) min β+ 182Os 3+
182m1Ir 71.02(17) keV 1990 170(40) ns IT 182Ir (5)+
182m2Ir 176.4(3) keV 1990 130(50) ns IT 182Ir (6)
183Ir 77 106 182.956841(26) 1961 58(5) min β+ 183Os 5/2
184Ir 77 107 183.957476(30) 1960 3.09(3) h β+ 184Os 5
184m1Ir 225.65(11) keV 1988 470(30) μs IT 184Ir 3+
184m2Ir 328.40(24) keV 1988 350(90) ns IT 184Ir 7+
185Ir 77 108 184.956698(30) 1958 14.4(1) h β+ 185Os 5/2
185mIr 2197(23) keV 1979 120(20) ns IT 185Ir (23/2,25/2)#
186Ir 77 109 185.957947(18) 1958 16.64(3) h β+ 186Os 5+
186mIr 0.8(4) keV 1962 1.92(5) h β+ (~75%) 186Os 2
IT (~25%) 186Ir
187Ir 77 110 186.957542(30) 1958 10.5(3) h β+ 187Os 3/2+
187m1Ir 186.16(4) keV 1963 30.3(6) ms IT 187Ir 9/2
187m2Ir 433.75(6) keV 1969 152(12) ns IT 187Ir 11/2
187m3Ir 2487.7(4) keV 2010 1.8(5) μs IT 187Ir 29/2
188Ir 77 111 187.958835(10) 1950 41.5(5) h β+ 188Os 1
188mIr 964(23) keV 1971 4.15(15) ms IT 188Ir 11#
189Ir 77 112 188.958723(14) 1955 13.2(1) d EC 189Os 3/2+
189m1Ir 372.17(4) keV 1963 13.3(3) ms IT 189Ir 11/2
189m2Ir 2332.8(3) keV 1975 3.7(2) ms IT 189Ir 25/2+
190Ir 77 113 189.9605434(15) 1947 11.7511(20) d[11] EC 190Os 4
β+ (<0.002%)[11]
190m1Ir 26.1(1) keV 1964 1.120(3) h IT 190Ir 1
190m2Ir 36.154(25) keV 1996 >2 μs IT 190Ir 4+
190m3Ir 376.4(1) keV 1950 3.087(12) h EC (91.4%) 190Os 11
IT (8.6%) 190Ir
191Ir 77 114 190.9605915(14) 1935 Observationally Stable[n 12] 3/2+ 0.373(2)
191m1Ir 171.29(4) keV 1954 4.899(23) s IT 191Ir 11/2
191m2Ir 2101.0(9) keV 2012 5.7(4) s IT 191Ir 31/2(+)
192Ir 77 115 191.9626024(14) 1937 73.820(14) d β (95.24%) 192Pt 4+
EC (4.76%) 192Os
192m1Ir 56.720(5) keV 1947 1.45(5) min IT (99.98%) 192Ir 1
β (0.0175%) 192Pt
192m2Ir 168.14(12) keV 1959 241(9) y IT 192Ir (11)
193Ir 77 116 192.9629238(14) 1935 Observationally Stable[n 13] 3/2+ 0.627(2)
193m1Ir 80.238(6) keV 1957 10.53(4) d IT 193Ir 11/2
193m2Ir 2278.9(5) keV 2012 124.8(21) μs IT 193Ir 31/2+
194Ir 77 117 193.9650757(14) 1937 19.35(7) h β 194Pt 1
194m1Ir 147.072(2) keV 1959 31.85(24) ms IT 194Ir 4+
194m2Ir 370(70) keV 1968 171(11) d β 194Pt (11)
195Ir 77 118 194.9659769(14) 1952 2.29(17) h β 195Pt 3/2+
195m1Ir 100(5) keV 1968 3.74(7) h β 195Pt 11/2
195m2Ir 2354(6) keV 2011 4.4(6) μs IT 195Ir (27/2+)
196Ir 77 119 195.968400(41) 1966 52.0(11) s β 196Pt (1,2)
196mIr 210(40) keV 1966 1.40(2) h β 196Pt 11#
197Ir 77 120 196.969657(22) 1952 5.8(5) min β 197Pt 3/2+
197m1Ir 115(5) keV (1978)[n 14] 8.9(3) min β 197Pt 11/2
197m2Ir 1700(500)#keV 2005 30(8) μs IT 197Ir
197m3Ir 2800(500)#keV 2005 15(9) μs IT 197Ir
198Ir 77 121 197.97240#(22) 1973 8.7(4) s β 198Pt 1
199Ir 77 122 198.973807(44) 1993 7(5) s β 199Pt 3/2+#
200Ir 77 123 199.97684#(21) 2008 43(6) s β 200Pt (2, 3)
201Ir 77 124 200.97870#(22) 2008 21(5) s β 201Pt (3/2+)
202Ir 77 125 201.98214#(32) 2008 11(3) s β 202Pt (2)
202mIr 2600(300)#keV 2011 3.4(6) μs IT 202Ir
203Ir 77 126 202.98457#(43) 2011 7# s [>300 ns] 3/2+#
203mIr 2140(50)#keV 2011 798(350) ns IT 203Ir
204Ir 77 127 203.98973#(43) 2011 2# s [>300 ns] 3/2+#
205Ir 77 128 204.99399#(54) 2012 1# s [>300 ns] 3/2+#
This table header & footer:
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  1. [1]
    mIr – Excited nuclear isomer.
  2. [2]
    ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. [3]
    # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. [4]
    # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  5. [5]
    Modes of decay:
    α:Alpha decay
    β+:Positron emission
    EC:Electron capture
    β−:Beta decay
    IT:Isomeric transition
    p:Proton emission
  6. [6]
    Bold italics symbol as daughter – Daughter product is nearly stable.
  7. [7]
    Bold symbol as daughter – Daughter product is stable.
  8. [8]
    ( ) spin value – Indicates spin with weak assignment arguments.
  9. [9]
    Discovery of this isotope is unconfirmed
  10. [10]
    Order of ground state and isomer is uncertain.
  11. [11]
    Half-life not measured, not included in discovery database
  12. [12]
    Believed to undergo α decay to 187Re[12][13]
  13. [13]
    Believed to undergo α decay to 189Re[12]
  14. [14]
    Only published in a conference proceeding and not a refereed journal

Iridium-192

Main article: Iridium-192

Iridium-192 (symbol 192Ir) is a radioactive isotope of iridium, with a half-life of 73.82 days.[14] It decays by emitting beta (β) particles and gamma (γ) radiation. 95.24% of 192Ir decays occur via β- emission, leading to 192Pt; the remaining 4.76% occur via electron capture to 192Os; both modes involve gamma emission. Iridium-192 is normally produced by neutron activation of natural-abundance iridium metal.[15]

Iridium-192 is used in brachytherapy and in industrial radiography, particularly for nondestructive testing of welds in steel in the oil and gas industries.

See also

Daughter products other than iridium

References

External links

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