Indium-111 is a radioisotope of the chemical element indium, which has 62 neutrons in its atomic nucleus in addition to the element-specific 49 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 111.
See also: list of Indium isotopes.
Indium-111 decays after electron capture (EE) with a half-life of 2.8 days and with emission of gamma radiation to the stable isotope Cadmium-111.
Half-life T½ = 2.8047(4) d respectively 2.4232608 × 105 seconds s.
| Decay mode | Daughter | Probability | Decay energy | γ energy (intensity) |
|---|---|---|---|---|
| EE | 111Cd | 100 % | 0.85763(17) MeV | 0.17128(3) MeV [90.7(9) %] 0.24535(4) MeV [94.1(10) %] |
List of some particle and radiation emissions (incomplete; intensities > 5% were taken into account):
| Energy [keV] | Intensity [%] | Type of radiation |
|---|---|---|
| 2,72 | 100 | Auger L |
| 3,13 | 6,78(17) | X: L |
| 19,3 | 15,5 | Auger K |
| 22,984 | 24,1(7) | X: Kα2 |
| 23,174 | 45,3(13) | X: Kα1 |
| 26,06 | 3,92(11) | X: Kβ3 |
| 26,095 | 7,55(22) | X: Kβ1 |
| 26,644 | 1,94(6) | X: Kβ2 |
| 144,47(3) | 7,87(24) | CE: K |
| 150,81(3) | 0,003 | gamma |
| 171,28(3) | 90,7(9) | gamma |
| 218,64(4) | 4,94(12) | CE: K |
| 245,35(4) | 94,1(10) | gamma |
| 422(5) | Neutrino |
[CE = conversion electrons; X: = X-rays]
Direct parent isotope is: 111Sn.
The amounts of indium-111 required for technical and medical purposes must be produced artificially, as the isotope does not occur naturally. A common method is to bombard enriched Cadmium-112 with protons in a cyclotron:
112Cd + 1p → 111In + 2 1n.
A second method, which gives lower yields but indium-111 with a higher isotopic purity, is the following reaction by bombarding a Silver-109 target with α particles (helium-4 atomic nuclei):
109Ag + 4He → 111In + 2 1n.
The Radiation Protection Ordinance (European Union), for example, specifies the following limit values for the isotope Indium-111 (exemption limits, clearance values and other values as a radioactive or highly radioactive source of radiation (HASS)):
Critical target organs in case of radioactive exposure to indium-111 are: bone marrow, colon, gonads, lungs.
Nuclear isomers or excited states with the activation energy in keV related to the ground state.
| Nuclear Isomer | Excitation Energy | Half-life | Spin |
|---|---|---|---|
| 111mIn | 536.99(7) keV | 7.7(2) min | 1/2- |
| Z | Isotone N = 62 | Isobar A = 111 |
|---|---|---|
| 35 | 97Br | |
| 36 | 98Kr | |
| 37 | 99Rb | |
| 38 | 100Sr | |
| 39 | 101Y | |
| 40 | 102Zr | 111Zr |
| 41 | 103Nb | 111Nb |
| 42 | 104Mo | 111Mo |
| 43 | 105Tc | 111Tc |
| 44 | 106Ru | 111Ru |
| 45 | 107Rh | 111Rh |
| 46 | 108Pd | 111Pd |
| 47 | 109Ag | 111Ag |
| 48 | 110Cd | 111Cd |
| 49 | 111In | 111In |
| 50 | 112Sn | 111Sn |
| 51 | 113Sb | 111Sb |
| 52 | 114Te | 111Te |
| 53 | 115I | 111I |
| 54 | 116Xe | 111Xe |
| 55 | 117Cs | |
| 56 | 118Ba | |
| 57 | 119La | |
| 58 | 120Ce | |
| 59 | 121Pr |
The following newer values were adopted for indium-111 from the recent literature:
[1] - Susanta Lahiri, Moumita Maiti, Kaustab Ghosh:
Production and separation of 111In: an important radionuclide in life sciences: a mini review.
In: Journal of Radioanalytical and Nuclear Chemistry, 297, (2013), DOI 10.1007/s10967-012-2344-3.
[2] - Z. Ge, T. Eronen, A. de Roubin et al.:
High-precision electron-capture Q value measurement of 111In for electron-neutrino mass determination.
In: Physical Letters B, 832, 137226, (2022), DOI 10.1016/j.physletb.2022.137226.
Last update: 2024-08-29
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