Notation. I write isotopes in the requested style with the mass number as a superscript at the upper‑left (e.g., ¹⁶¹Tb).
Columns. Z, A, stability, best half‑life, dominant decay mode(s) → main daughter(s), radiation type, typical origin (natural/activation/synthetic), and typical uses (R = research, M = medical, I = industrial).
Scope check. Terbium is mononuclidic in nature: only ¹⁵⁹Tb is stable (100%). The rest are synthetic radioisotopes produced by accelerators, reactors, or in‑flight fission; the most investigated for medicine are ¹⁴⁹Tb (α), ¹⁵²Tb (β⁺/EC, PET), ¹⁵⁵Tb (EC, SPECT), and ¹⁶¹Tb (β⁻, Auger, therapy). (CIAAW, Wikipedia, Nature, PRISMAP, ScienceDirect, PMC)
All terbium ground‑state isotopes
| Isotope | Z | A | Stable? | Half‑life (best value) | Decay → Daughter(s) | Radiation | Origin | Typical use |
|---|---|---|---|---|---|---|---|---|
| ¹³⁵Tb | 65 | 135 | No | 1.01 ms | p → ¹³⁴Gd | p | Synthetic (very p‑rich) | R (nuclear structure) (Wikipedia) |
| ¹³⁶Tb | 65 | 136 | No | 200 ms | β⁺ → ¹³⁶Gd | β⁺ | Synthetic (p‑rich) | R (Periodic Table) |
| ¹³⁷Tb | 65 | 137 | No | 600 ms | p / β⁺ → ¹³⁶Gd / ¹³⁷Gd | p, β⁺ | Synthetic (p‑rich) | R (Periodic Table) |
| ¹³⁸Tb | 65 | 138 | No | 800 ms | β⁺ (dominant) → ¹³⁸Gd | β⁺ | Synthetic (p‑rich) | R (Periodic Table) |
| ¹³⁹Tb | 65 | 139 | No | 1.6 s | β⁺ → ¹³⁹Gd | β⁺ | Synthetic | R (Wikipedia) |
| ¹⁴⁰Tb | 65 | 140 | No | 2.29 s | β⁺ (dominant), EC (minor); β⁺,p (minor) → ¹⁴⁰Gd / ¹³⁹Eu | β⁺, EC, p | Synthetic | R (Wikipedia) |
| ¹⁴¹Tb | 65 | 141 | No | 3.5 s | β⁺ → ¹⁴¹Gd | β⁺ | Synthetic | R (Wikipedia) |
| ¹⁴²Tb | 65 | 142 | No | 597 ms | β⁺ (dominant), EC (minor); β⁺,p (trace) → ¹⁴²Gd / ¹⁴¹Eu | β⁺, EC, p | Synthetic | R (Wikipedia) |
| ¹⁴³Tb | 65 | 143 | No | 12 s | β⁺ → ¹⁴³Gd | β⁺ | Synthetic | R (Wikipedia) |
| ¹⁴⁴Tb | 65 | 144 | No | ~1 s | β⁺ → ¹⁴⁴Gd | β⁺ | Synthetic | R (Wikipedia) |
| ¹⁴⁵Tb | 65 | 145 | No | 30.9 s | β⁺ → ¹⁴⁵Gd | β⁺ | Synthetic | R (Wikipedia) |
| ¹⁴⁶Tb | 65 | 146 | No | 8 s | β⁺ → ¹⁴⁶Gd | β⁺ | Synthetic | R (Wikipedia) |
| ¹⁴⁷Tb | 65 | 147 | No | 1.64 h | β⁺ → ¹⁴⁷Gd | β⁺ (γ) | Synthetic | R (chemistry tracers) (Wikipedia) |
| ¹⁴⁸Tb | 65 | 148 | No | 60 min | β⁺ → ¹⁴⁸Gd | β⁺ (γ) | Synthetic | R (Wikipedia) |
| ¹⁴⁹Tb | 65 | 149 | No | 4.118 h | β⁺ (83.3%) → ¹⁴⁹Gd; α (16.7%) → ¹⁴⁵Eu | β⁺, α | Synthetic | M: targeted α‑therapy & “α‑PET” theranostics; R (Wikipedia, Nature) |
| ¹⁵⁰Tb | 65 | 150 | No | 3.48 h | β⁺ → ¹⁵⁰Gd | β⁺ | Synthetic | R (Wikipedia) |
| ¹⁵¹Tb | 65 | 151 | No | 17.609 h | β⁺ (≈100%) → ¹⁵¹Gd; tiny α branch → ¹⁴⁷Eu | β⁺ (γ), α (trace) | Synthetic | R (Wikipedia) |
| ¹⁵²Tb | 65 | 152 | No | 17.8784 h | EC (≈83%) / β⁺ (≈17%) → ¹⁵²Gd; α ≪ 1 ppm | EC, β⁺ (γ) | Synthetic | M: PET imaging (short‑lived Tb‑PET); theranostic partner for ¹⁶¹Tb (Wikipedia, PRISMAP) |
| ¹⁵³Tb | 65 | 153 | No | 2.34 d | β⁺ → ¹⁵³Gd | β⁺ (γ) | Synthetic | R (route to ¹⁵³Gd studies) (Wikipedia) |
| ¹⁵⁴Tb | 65 | 154 | No | 9.994 h | β⁺ → ¹⁵⁴Gd | β⁺ (γ) | Synthetic | R (Wikipedia) |
| ¹⁵⁵Tb | 65 | 155 | No | 5.2346 d | EC → ¹⁵⁵Gd | EC (γ) | Synthetic | M: SPECT imaging; mass‑separated production at CERN‑MEDICIS (Wikipedia, ScienceDirect) |
| ¹⁵⁶Tb | 65 | 156 | No | 5.35 d | β⁺ → ¹⁵⁶Gd | β⁺ (γ) | Synthetic | R (Wikipedia) |
| ¹⁵⁷Tb | 65 | 157 | No | 71 y | EC → ¹⁵⁷Gd | EC (γ) | Synthetic (long‑lived) | R (metrology; decay‑data standards) (Wikipedia, ScienceDirect) |
| ¹⁵⁸Tb | 65 | 158 | No | 180 y | β⁺ (~83%) → ¹⁵⁸Gd; β⁻ (~17%) → ¹⁵⁸Dy | β⁺/β⁻ (γ) | Synthetic (long‑lived) | R (metrology; background studies) (Wikipedia) |
| ¹⁵⁹Tb | 65 | 159 | Yes | Stable | — | — | Natural (100%) | I/R: NMR‑active stable nuclide (I = 3/2); targets for activation to ¹⁶⁰Tb (CIAAW, NMR) |
| ¹⁶⁰Tb | 65 | 160 | No | 72.3 d | β⁻ → ¹⁶⁰Dy | β⁻ (γ) | Activation: ¹⁵⁹Tb(n,γ) | R/I: γ‑emitter used as tracer & calibration source (Wikipedia, JAEA Nuclear Data Center, MIRDSoft) |
| ¹⁶¹Tb | 65 | 161 | No | 6.948 d | β⁻ → ¹⁶¹Dy | β⁻ + abundant conversion/Auger e⁻ | Reactor route ¹⁶⁰Gd(n,γ)→¹⁶¹Gd→¹⁶¹Tb; Cyclotron ¹⁶⁰Gd(d,n) | M: β⁻ therapy; SPECT‑able “theranostic” partner to ¹⁵²/¹⁵⁵Tb (Wikipedia, ScienceDirect, PMC, InspireHEP) |
| ¹⁶²Tb | 65 | 162 | No | 7.60 min | β⁻ → ¹⁶²Dy | β⁻ | Synthetic (n‑rich; fission/fragmentation) | R (Wikipedia, Periodic Table) |
| ¹⁶³Tb | 65 | 163 | No | 19.5 min | β⁻ → ¹⁶³Dy | β⁻ | Synthetic | R (Wikipedia) |
| ¹⁶⁴Tb | 65 | 164 | No | 3.0 min | β⁻ → ¹⁶⁴Dy | β⁻ | Synthetic | R (Wikipedia) |
| ¹⁶⁵Tb | 65 | 165 | No | 2.11 min | β⁻ → ¹⁶⁵Dy | β⁻ | Synthetic | R (Wikipedia) |
| ¹⁶⁶Tb | 65 | 166 | No | 27.1 s | β⁻ → ¹⁶⁶Dy | β⁻ | Synthetic | R (Wikipedia) |
| ¹⁶⁷Tb | 65 | 167 | No | 18.9 s | β⁻ → ¹⁶⁷Dy | β⁻ | Synthetic | R (Wikipedia) |
| ¹⁶⁸Tb | 65 | 168 | No | 9.4 s | β⁻ → ¹⁶⁸Dy | β⁻ | Synthetic | R (Wikipedia) |
| ¹⁶⁹Tb | 65 | 169 | No | 5.13 s | β⁻ → ¹⁶⁹Dy | β⁻ | Synthetic | R (Wikipedia) |
| ¹⁷⁰Tb | 65 | 170 | No | 960 ms | β⁻ → ¹⁷⁰Dy | β⁻ | Synthetic | R (Wikipedia) |
| ¹⁷¹Tb | 65 | 171 | No | 1.23 s | β⁻ → ¹⁷¹Dy | β⁻ | Synthetic | R (Wikipedia) |
| ¹⁷²Tb | 65 | 172 | No | 760 ms | β⁻ → ¹⁷²Dy | β⁻ | Synthetic | R (Wikipedia) |
| ¹⁷³Tb | 65 | 173 | No | ~400 ms | (β⁻, very short‑lived) | β⁻ | Synthetic | R (Wikipedia) |
| ¹⁷⁴Tb | 65 | 174 | No | ~240 ms | (β⁻, very short‑lived) | β⁻ | Synthetic | R (Wikipedia) |
Selected isomers (for context): long‑lived metastables include ¹⁵⁶m2Tb (24.4 h) and ¹⁵⁴m2Tb (22.7 h); among short‑lived isomers: ¹⁵²m2Tb (4.2 min), ¹⁵¹mTb (25 s), etc. (useful in decay‑scheme work and γ‑spectrometry). (Wikipedia)
Element‑level tallies (Tb)
- Stable: 1 (¹⁵⁹Tb)
- Unstable (radioisotopes): 39 (from ¹³⁵Tb up to ¹⁷⁴Tb, excluding ¹⁵⁹)
- Total ground‑state isotopes: 40
- Known isomeric (metastable) states: ~27 reported.
Counts align with the most recent “Terbium” overview noting 39 radioisotopes characterized from A = 135–174. (Wikipedia)
Use notes (the “why do we care?” layer)
- ¹⁶¹Tb (β⁻, t½≈6.95 d) – emits β⁻ plus conversion/Auger electrons; promising therapeutic radionuclide with imaging‑friendly γ lines; scalable production via ¹⁶⁰Gd(n,γ)→¹⁶¹Gd→¹⁶¹Tb and cyclotron ¹⁶⁰Gd(d,n). (PMC, ScienceDirect, Journal of Nuclear Medicine, InspireHEP)
- ¹⁵²Tb (β⁺/EC, t½≈17.9 h) – PET radionuclide; lines around 344 keV useful; explored for three‑photon PET modalities; ideal theranostic partner to ¹⁶¹Tb. (PRISMAP)
- ¹⁵⁵Tb (EC, t½≈5.23 d) – SPECT imaging candidate; recent precision half‑life and production work (mass‑separated beams). (ScienceDirect)
- ¹⁴⁹Tb (α + β⁺, t½≈4.12 h) – targeted α‑therapy with same‑element PET capability (α‑PET); intensively studied routes and preclinical data. (Nature)
- ¹⁶⁰Tb (β⁻, t½≈72.3 d) – activation product from ¹⁵⁹Tb(n,γ); used as γ‑emitting tracer and in calibration/decay‑data evaluations. (JAEA Nuclear Data Center, MIRDSoft)
- ¹⁵⁹Tb (stable) – NMR‑active I = 3/2 nuclide used for solid‑state NMR in rare‑earth compounds; also a common target for producing ¹⁶⁰Tb by neutron capture. (NMR)
Sources (primary data tables & specialty references)
- Comprehensive isotope list, half‑lives & dominant decay branches/daughters: Isotopes of terbium (evaluated table). (Wikipedia)
- Very proton‑rich Tb (A = 136–138) with β⁺/p branches: PeriodicTable.com isotope pages (interactive decay data). (Periodic Table)
- Counts / mononuclidic nature: CIAAW (IUPAC Commission) Terbium page; Wikipedia Terbium overview (updated). (CIAAW, Wikipedia)
- Medical terbium isotopes: ¹⁶¹Tb (therapy)—Müller et al., JNM & reviews; production via ¹⁶⁰Gd(n,γ)→¹⁶¹Gd→¹⁶¹Tb and ¹⁶⁰Gd(d,n) routes; DOE IP note. (PMC, ScienceDirect, Journal of Nuclear Medicine, InspireHEP, The Department of Energy’s Energy.gov)
- ¹⁵²Tb PET: PRISMAP radionuclide dossier. (PRISMAP)
- ¹⁵⁵Tb SPECT & half‑life: CERN‑MEDICIS/Applied Radiation & Isotopes. (ScienceDirect)
- ¹⁴⁹Tb α‑therapy & α‑PET: Müller et al. 2016; Favaretto et al. 2024. (Nature)
- ¹⁶⁰Tb decay data & γ lines: JAEA decay‑data table; MIRD/ICRP compilations. (JAEA Nuclear Data Center, MIRDSoft)
Consistency note. The “Isotopes of terbium” table historically listed 37 radioisotopes; newer summaries (and the PeriodicTable.com pages for ¹³⁶–¹³⁸Tb) support 39 radioisotopes + 1 stable = 40 ground‑state isotopes. I’ve adopted the latter, more up‑to‑date count. (Wikipedia, Periodic Table)
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