Isotopes of indium

Isotopes of indium (49In)
Main isotopes[1] Decay
abun­dance half-life (t1/2) mode pro­duct
111In synth 2.8 d ε 111Cd
113In 4.28% stable
115In 95.7% 4.41×1014 y β− 115Sn
Standard atomic weight Ar°(In)

Indium (49In) consists of two primordial nuclides, with the most common (~ 95.7%) nuclide (115In) being measurably though weakly radioactive. Its spin-forbidden decay has a half-life of 4.41×1014 years, much longer than the currently accepted age of the Universe.

The stable isotope 113In is only 4.3% of naturally occurring indium. Among elements with a known stable isotope, only tellurium and rhenium similarly occur with a stable isotope in lower abundance than the long-lived radioactive isotope. Other than 115In, the longest-lived radioisotope is 111In, with a half-life of 2.8047 days. All other radioisotopes have half-lives less than a day. This element also has 47 isomers, the longest-lived being 114m1In, with a half-life of 49.51 days. All other meta-states have half-lives less than a day, most less than an hour, and many measured in milliseconds or less.

Indium-111 is used medically in nuclear imaging, as a radiotracer nuclide tag for gamma camera localization of protein radiopharmaceuticals, such as In-111-labeled octreotide, which binds to receptors on certain endocrine tumors (Octreoscan).[4] Indium-111 is also used in indium white blood cell scans, which use nuclear medical techniques to search for hidden infections.

Several proton-rich isotopes of indium (including indium-99) have been used to measure the mass of the doubly-magic isotope tin-100.[5][6]

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  4. ^ "Octreoscan review". Medscape.
  5. ^ "Precision mass measurements of indium isotopes allow conclusions on the mass of the doubly-magic atomic nucleus of tin-100". GSI. 13 June 2012. Retrieved 2023-09-10.
  6. ^ "Tin 100 probed by studying its neighboring isotopes, indium 99 and 101 – IJCLab". Retrieved 2023-09-10.