Editing Holmium (section)

===Isotopes===
{{further|Isotopes of holmium}}

The isotopes of holmium range from <sup>140</sup>Ho to <sup>175</sup>Ho. The primary [[decay mode]] before the most abundant [[stable isotope]], <sup>165</sup>Ho, is [[positron emission]], and the primary mode after is [[beta minus decay]]. The primary [[decay product]]s before <sup>165</sup>Ho are [[terbium]] and [[dysprosium]] isotopes, and the primary products after are [[erbium]] isotopes.<ref name="CRC" />

Natural holmium consists of one [[primordial isotope]], holmium-165;<ref name="emsley226" /> it is the only isotope of holmium that is thought to be stable, although it is predicted to undergo [[alpha decay]] to [[terbium-161]] with a very long half-life.<ref>{{cite journal |last1=Belli |first1=P. |last2=Bernabei |first2=R. |last3=Danevich |first3=F. A. |last4=Incicchitti |first4=A. |last5=Tretyak |first5=V. I. |display-authors=3 |title=Experimental searches for rare alpha and beta decays |journal=European Physical Journal A |date=2019 |volume=55 |issue=8 |pages=140–1–140–7 |doi=10.1140/epja/i2019-12823-2 |issn=1434-601X |arxiv=1908.11458|bibcode=2019EPJA...55..140B |s2cid=201664098 }}</ref> Of the 35 [[synthetic element|synthetic]] radioactive isotopes that are known, the most stable one is holmium-163 (<sup>163</sup>Ho), with a half-life of 4570 years.<ref>{{Cite journal |last1=Naumann |first1=R. A. |last2=Michel |first2=M. C. |last3=Power |first3=J. L. |title=Preparation of long-lived holmium-163 |date=September 1960 |osti=4120223 |journal=Journal of Inorganic and Nuclear Chemistry |language=en |volume=15 |issue=1–2 |pages=195–196 |doi=10.1016/0022-1902(60)80035-8}}</ref> All other radioisotopes have ground-state half-lives not greater than 1.117 days, with the longest, holmium-166 (<sup>166</sup>Ho) having a half-life of 26.83 hours,<ref>{{Cite journal |last=Suzuki |first=Yuka S |year=1998 |title=Biodistribution and kinetics of holmium-166-chitosan complex (DW-166HC) in rats and mice. |url=https://jnm.snmjournals.org/content/jnumed/39/12/2161.full.pdf |journal=Journal of Nuclear Medicine |volume=39 |issue=12 |pages=2161–2166|pmid=9867162 }}</ref> and most have half-lives under 3 hours.

<sup>166m1</sup>Ho has a half-life of around 1200 years.<ref>{{Cite journal |last1=Klaassen |first1=Nienke J. M. |last2=Arntz |first2=Mark J. |last3=Gil Arranja |first3=Alexandra |last4=Roosen |first4=Joey |last5=Nijsen |first5=J. Frank W. |date=2019-08-05 |title=The various therapeutic applications of the medical isotope holmium-166: a narrative review |journal=EJNMMI Radiopharmacy and Chemistry |volume=4 |issue=1 |pages=19 |doi=10.1186/s41181-019-0066-3 |issn=2365-421X |pmid=31659560|pmc=6682843 |doi-access=free }}</ref> The high excitation energy, resulting in a particularly rich spectrum of decay [[gamma ray]]s produced when the metastable state de-excites, makes this isotope useful as a means for [[Calibration|calibrating]] [[gamma ray spectrometer]]s.<ref>{{Cite web |last=Oliveira |first=Bernardes, Estela Maria de |date=2001-01-01 |title=Holmium-166m: multi-gamma standard to determine the activity of radionuclides in semiconductor detectors |url=https://inis.iaea.org/search/search.aspx?orig_q=RN:43130653 |language=Portuguese}}</ref>