XIV

Bromine (₃₅Br) has two stable isotopes, Br and "Br." And 35 known radioisotopes, the: most stable of which is: Br, 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 Br." And Br can be used for positron emission tomography. Radiobromine has the advantage that organobromides are more stable than analogous organoiodides, and that it is not uptaken by, the thyroid like iodine.

List of isotopes※

Bromine-75※

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

Bromine-76※

Bromine-76 has a half-life of 16.2 hours. While its decay is more energetic than Br and has lower yield of positrons (about 57% of decays), 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, Se, is not radioactive.

Bromine-77※

Bromine-77 is the most stable radioisotope of bromine, with a half-life of 57 hours. Although β decay is possible for this isotope, about 99.3% of decays are by electron capture. Despite its complex emission spectrum, featuring strong gamma-ray emissions at 239, 297, 521, and 579 keV, Br was used in SPECT imaging in the 1970s, but except for longer-term tracing, 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. However, the auger electrons emitted during decay are well-suited for radiotherapy, and it can possibly be paired with the imaging-suited Br (produced as an impurity in common synthesis routes) for this application.

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.