Bromine (₃₅Br) has two stable isotopes, ⁷⁹Br and ⁸¹Br, and 32 known radioisotopes, the most stable of which is ⁷⁷Br, with a half-life of 57.036 hours.

Like the radioactive isotopes of iodine, radioisotopes of bromine, collectively radiobromine, can be used to label biomolecules for nuclear medicine; for example, the positron emitters ⁷⁵Br and ⁷⁶Br can be used for positron emission tomography.^[4][5] Radiobromine has the advantage that organobromides are more stable than analogous organoiodides, and that it is not uptaken by the thyroid like iodine.^[6]

List of isotopes

Bromine-75

Bromine-75 has a half-life of 97 minutes.^[11] This isotope undergoes β⁺ decay rather than electron capture about 76% of the time,^[6] so it was used for diagnosis and positron emission tomography (PET) in the 1980s.^[4] However, its decay product, selenium-75, produces secondary radioactivity with a longer half-life of 120.4 days.^[6][4]

Bromine-76

Bromine-76 has a half-life of 16.2 hours.^[11] While its decay is more energetic than ⁷⁵Br and has lower yield of positrons (about 57% of decays),^[6] bromine-76 has been preferred in PET applications since the 1980s because of its longer half-life and easier synthesis, and because its decay product, ⁷⁶Se, is not radioactive.^[5]

Bromine-77

Bromine-77 is the most stable radioisotope of bromine, with a half-life of 57 hours.^[11] Although β⁺ decay is possible for this isotope, about 99.3% of decays are by electron capture.^[9] Despite its complex emission spectrum, featuring strong gamma-ray emissions at 239, 297, 521, and 579 keV,^{[12] 77}Br was used in SPECT imaging in the 1970s,^[13] but except for longer-term tracing,^[6] this is no longer considered practical due to the difficult collimator requirements and the proximity of the 521 keV line to the 511 keV annihilation radiation related to the β⁺ decay.^[13] However, the auger electrons emitted during decay are well-suited for radiotherapy, and it can possibly be paired with the imaging-suited ⁷⁶Br (produced as an impurity in common synthesis routes) for this application.^[4][13]

References

• Isotope masses from:
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
• Isotopic compositions and standard atomic masses from:
  • de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
  • Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051.
• "News & Notices: Standard Atomic Weights Revised". International Union of Pure and Applied Chemistry. 19 October 2005.
• Half-life, spin, and isomer data selected from the following sources.
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  • National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
  • Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.