Editing Iridium (section)

=== Isotopes ===
{{Main|Isotopes of iridium}}
Iridium has two naturally occurring stable [[isotope]]s, <sup>191</sup>Ir and <sup>193</sup>Ir, with [[natural abundance]]s of 37.3% and 62.7%, respectively.<ref name="nubase" /> At least 37 [[radioisotope]]s have also been synthesized, ranging in [[mass number]] from 164 to 202. [[iridium-192|<sup>192</sup>Ir]], which falls between the two stable isotopes, is the most stable [[Radionuclide|radioisotope]], with a [[half-life]] of 73.827&nbsp;days, and finds application in [[brachytherapy]]<ref name="mager" /> and in industrial [[radiography]], particularly for [[nondestructive testing]] of welds in steel in the oil and gas industries; iridium-192 sources have been involved in a number of radiological accidents. Three other isotopes have half-lives of at least a day—<sup>188</sup>Ir, <sup>189</sup>Ir, and <sup>190</sup>Ir.<ref name="nubase" /> Isotopes with masses below 191 decay by some combination of [[Beta decay#β+ decay|β<sup>+</sup> decay]], [[alpha decay|α decay]], and (rare) [[proton emission]], with the exception of <sup>189</sup>Ir, which decays by [[electron capture]]. Synthetic isotopes heavier than 191 decay by [[Beta decay#β− decay|β<sup>−</sup> decay]], although <sup>192</sup>Ir also has a minor electron capture decay path.<ref name="nubase">{{NUBASE 2003}}</ref> All known isotopes of iridium were discovered between 1934 and 2008, with the most recent discoveries being <sup>200–202</sup>Ir.<ref>{{cite journal |title=Discovery of tantalum, rhenium, osmium, and iridium isotopes |last1=Robinson |first1=R. |last2=Thoennessen |first2=M. |journal=Atomic Data and Nuclear Data Tables |volume=98 |issue=5 |date=2012 |pages=911–932 |arxiv=1109.0526 |doi=10.1016/j.adt.2011.09.003 |bibcode=2012ADNDT..98..911R |s2cid=53992437}}</ref>

At least 32 [[nuclear isomer|metastable isomers]] have been characterized, ranging in mass number from 164 to 197. The most stable of these is <sup>192m2</sup>Ir, which decays by [[isomeric transition]] with a half-life of 241&nbsp;years,<ref name="nubase" /> making it more stable than any of iridium's synthetic isotopes in their ground states. The least stable isomer is <sup>190m3</sup>Ir with a half-life of only 2&nbsp;μs.<ref name="nubase" /> The isotope <sup>191</sup>Ir 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]].<ref name="ir-191">{{cite book |title=Handbook of Ceramics and Composites |author=Chereminisoff, N. P. |publisher=CRC Press |date=1990 |isbn=978-0-8247-8006-7 |page=424}}</ref>