Editing Astatine (section)

=== Formation ===
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{| class="wikitable"
|+ Possible reactions after bombarding bismuth-209 with alpha particles
!rowspan=2| Reaction{{efn|A nuclide is commonly denoted by a symbol of the chemical element this nuclide belongs to, <!--if someone can come up with a better wording, please do, or, if you think it's okay, just remove this message--> preceded by a non-spaced superscript mass number and a subscript atomic number of the nuclide located directly under the mass number. (Neutrons may be considered as nuclei with the atomic mass of 1 and the atomic charge of 0, with the symbol being n.) With the atomic number omitted, it is also sometimes used as a designation of an isotope of an element in isotope-related chemistry.}}
!colspan=2| Energy of alpha particle
|-
! Threshold energy
! Maximum production
|-
| style="text-align:center;"| {{chem|209|83|Bi}} + {{chem|4|2|He}} → {{chem|211|85|At}} + 2 {{chem|1|0}}n
| style="text-align:center;"| 20.7&nbsp;MeV<ref name="Hermanne"/>
| style="text-align:center;"| 30<ref name="Gyehong"/>–31&nbsp;MeV<ref name="Hermanne"/>
|-
| style="text-align:center;"| {{chem|209|83|Bi}} + {{chem|4|2|He}} → {{chem|210|85|At}} + 3 {{chem|1|0}}n
| style="text-align:center;"| 28.4<ref name="zalutsky"/>–28.6&nbsp;MeV<ref name="Hermanne"/><ref name="Maiti"/>
| style="text-align:center;"| 37&nbsp;MeV<ref name="Hermanne">{{cite journal | last1=Hermanne | first1=A. | last2=Tárkányi | first2=F. | last3=Takács | first3=S. | last4=Szücs | first4=Z. | last5=Shubin | first5=Yu.N. | last6=Dityuk | first6=A.I. | title=Experimental study of the cross-sections of α-particle induced reactions on 209Bi | journal=Applied Radiation and Isotopes | publisher=Elsevier BV | volume=63 | issue=1 | year=2005 | issn=0969-8043 | doi=10.1016/j.apradiso.2005.01.015 | pages=1–9}}</ref>
|-
| style="text-align:center;"| {{chem|209|83|Bi}} + {{chem|4|2|He}} → {{chem|209|85|At}} + 4 {{chem|1|0}}n
| style="text-align:center;"| 35.9&nbsp;MeV<ref name="Maiti">{{cite journal | last1=Maiti | first1=Moumita | last2=Lahiri | first2=Susanta | last3=Kumar | first3=Deepak | last4=Choudhury | first4=Dibyasree | title=Separation of no-carrier-added astatine radionuclides from α-particle irradiated lead bismuth eutectic target: A classical method | journal=Applied Radiation and Isotopes | publisher=Elsevier BV | volume=127 | year=2017 | issn=0969-8043 | doi=10.1016/j.apradiso.2017.06.020 | pages=227–230| pmid=28649020 | bibcode=2017AppRI.127..227M }}</ref>
| style="text-align:center;"|
|}
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[[File:Astatine-211 in bismuth target.jpg|thumb|left|The bismuth target after irradiation contains minuscule quantities of astatine-211.<ref>{{cite journal | last1=Naka | first1=Sadahiro | last2=Ooe | first2=Kazuhiro | last3=Shirakami | first3=Yoshifumi | last4=Kurimoto | first4=Kenta | last5=Sakai | first5=Toshihiro | last6=Takahashi | first6=Kazuhiro | last7=Toyoshima | first7=Atsushi | last8=Wang | first8=Yang | last9=Haba | first9=Hiromitsu | last10=Kato | first10=Hiroki | last11=Tomiyama | first11=Noriyuki | last12=Watabe | first12=Tadashi | title=Production of [211At]NaAt solution under GMP compliance for investigator-initiated clinical trial | journal=EJNMMI Radiopharmacy and Chemistry | volume=9 | issue=1 | date=2024-04-15 | issn=2365-421X | pmid=38619655 | pmc=11018728 | doi=10.1186/s41181-024-00257-z | doi-access=free}}</ref>]]

Astatine was first produced by bombarding bismuth-209 with energetic alpha particles, and this is still the major route used to create the relatively long-lived isotopes astatine-209 through astatine-211. Astatine is only produced in minuscule quantities, with modern techniques allowing production runs of up to 6.6&nbsp;[[gigabecquerel]]s<ref name="zalutsky"/> (about 86&nbsp;[[nanogram]]s or 2.47{{e|14}} atoms). Synthesis of greater quantities of astatine using this method is constrained by the limited availability of suitable cyclotrons and the prospect of melting the target.<ref name="zalutsky"/><ref name="Larsen" />{{efn|See however Nagatsu et al.<ref>{{cite journal |first1=K.|last1=Nagatsu|first2=K. H.|last2=Minegishi|first3=M. |last3=Fukada |first4=H. |last4=Suzuki |first5=S.|last5=Hasegawa |first6=M. |last6=Zhang|year=2014 |title=Production of <sup>211</sup>At by a vertical beam irradiation method|journal=Applied Radiation and Isotopes |volume=94 |pages=363–371 |doi=10.1016/j.apradiso.2014.09.012|pmid=25439168|bibcode=2014AppRI..94..363N }}</ref> who encapsulate the bismuth target in a thin aluminium foil and place it in a niobium holder capable of holding molten bismuth.}} Solvent [[radiolysis]] due to the cumulative effect of astatine decay<ref>{{cite book | title = Therapeutic Nuclear Medicine| year = 2014 | pages = 95–104 (99) | publisher = Springer | isbn = 978-3-540-36718-5 | last1 = Barbet | first1 = J. | last2 = Bourgeois | first2 = M.|first3= J.|last3= Chatal|editor1 = R. P.|editor2 = Baum|chapter= Cyclotron-Based Radiopharmaceuticals for Nuclear Medicine Therapy}}</ref> is a related problem. With cryogenic technology, [[microgram]] quantities of astatine might be able to be generated via proton irradiation of [[thorium]] or [[uranium]] to yield radon-211, in turn decaying to astatine-211. Contamination with astatine-210 is expected to be a drawback of this method.<ref name="Wilbur">{{cite journal | last = Wilbur| first = D. S. | date = 2001| title = Overcoming the Obstacles to Clinical Evaluation of <sup>211</sup>At-Labeled Radiopharmaceuticals | journal = The Journal of Nuclear Medicine | volume = 42 | issue = 10 | pages = 1516–1518 | url=http://jnm.snmjournals.org/content/42/10/1516|pmid=11585866}}</ref>

The most important isotope is astatine-211, the only one in commercial use. To produce the bismuth target, the metal is [[sputtering|sputtered]] onto a gold, copper, or aluminium surface at 50 to 100 milligrams per square centimeter. [[Bismuth oxide]] can be used instead; this is forcibly fused with a copper plate.{{sfn|Lavrukhina|Pozdnyakov|1970|p=233}} The target is kept under a [[Nitrogen gas#Reactions|chemically neutral nitrogen]] atmosphere,<ref name="BiN2">{{cite book|title=Inorganic Chemistry for Undergraduates|first=R. |last=Gopalan |year=2009|page=547|publisher=Universities Press | isbn = 978-81-7371-660-7 | url = https://books.google.com/books?id=Fs4zQ-hNTz8C&pg=PA492}}</ref> and is cooled with water to prevent premature astatine vaporization.{{sfn|Lavrukhina|Pozdnyakov|1970|p=233}} In a particle accelerator, such as a cyclotron,<ref>{{cite book|title=Targeted Radionuclide Tumor Therapy: Biological Aspects|first1=T.|last1=Stigbrand |first2=J. |last2=Carlsson |first3=G. P.|last3=Adams|year=2008|page=150|publisher=Springer | isbn = 978-1-4020-8695-3 | url = https://books.google.com/books?id=-mT0Lthq_54C}}</ref> alpha particles are collided with the bismuth. Even though only one bismuth isotope is used (bismuth-209), the reaction may occur in three possible ways, producing astatine-209, astatine-210, or astatine-211. Although higher energies can produce more astatine-211, it will produce unwanted astatine-210 that decays to toxic polonium-210 as well. Instead, the maximum energy of the particle accelerator is set to be below or slightly above the threshold of astatine-210 production, in order to maximize the production of astatine-211 while keeping the amount of astatine-210 at an acceptable level.<ref name="zalutsky"/><ref name="Gyehong">{{cite journal |first1=G.|last1=Gyehong |first2=K.|last2=Chun|first3=S. H. |last3=Park |first4=B.|last4=Kim|year=2014 |title=Production of α-particle emitting <sup>211</sup>At using 45&nbsp;MeV α-beam| journal=Physics in Medicine and Biology |volume=59 |issue=11|pages=2849–2860| doi=10.1088/0031-9155/59/11/2849|pmid=24819557 |bibcode = 2014PMB....59.2849K |s2cid=21973246 }}</ref>