Notation. Nuclides shown with mass number as a left superscript (e.g., ¹³⁹La).
Columns. Stable? refers to the ground state; selected isomers noted afterward. Half‑life and Decay mode(s) (main branches) are evaluated values; Daughter lists the immediate product(s). Radiation summarizes particle/γ emissions. Origin sketches typical production route. Uses flags notable M (medical), I (industrial), R (research).
Data spine. Evaluated half‑lives/branches/daughters are from the consolidated “Isotopes of lanthanum” table (reflecting NUBASE/ENSDF); natural composition from CIAAW; specialized usage/gamma data from primary sources cited in‑line.
Lanthanum — ground states (key isomers follow)
| Isotope | Z | A | Stable? | Half‑life | Decay mode(s) (main %) | Daughter(s) | Radiation | Origin | Uses / notes |
|---|---|---|---|---|---|---|---|---|---|
| ¹¹⁶La | 57 | 116 | No | ~50 ms | p (~60%), β⁺ (~40%) | ¹¹⁵Ba, ¹¹⁶Ba | p, β⁺ | Synthetic (p‑rich) | R. |
| ¹¹⁷La | 57 | 117 | No | ~21.6 ms | p (94%), β⁺ (6%) | ¹¹⁶Ba, ¹¹⁷Ba | p, β⁺ | Synthetic (p‑rich) | R. |
| ¹¹⁸La | 57 | 118 | No | ~1 s (est.) | β⁺ | ¹¹⁸Ba | β⁺ | Synthetic | R; sparse data. |
| ¹¹⁹La | 57 | 119 | No | ~2 s (est.) | β⁺ | ¹¹⁹Ba | β⁺ | Synthetic | R; sparse data. |
| ¹²⁰La | 57 | 120 | No | ~2.8 s | β⁺ (±p tiny) | ¹²⁰Ba (→ ¹¹⁹Cs via β⁺p) | β⁺ (+p) | Synthetic | R. |
| ¹²¹La | 57 | 121 | No | ~5.3 s | β⁺ | ¹²¹Ba | β⁺ | Synthetic | R. |
| ¹²²La | 57 | 122 | No | ~8.6 s | β⁺ (±p tiny) | ¹²²Ba (→ ¹²¹Cs) | β⁺ (+p) | Synthetic | R. |
| ¹²³La | 57 | 123 | No | ~17 s | β⁺ | ¹²³Ba | β⁺ | Synthetic | R. |
| ¹²⁴La | 57 | 124 | No | ~29.2 s | β⁺ | ¹²⁴Ba | β⁺ | Synthetic | R. |
| ¹²⁵La | 57 | 125 | No | ~64.8 s | β⁺ | ¹²⁵Ba | β⁺ | Synthetic | R. |
| ¹²⁶La | 57 | 126 | No | ~54 s | β⁺ | ¹²⁶Ba | β⁺ | Synthetic | R. |
| ¹²⁷La | 57 | 127 | No | ~5.1 min | β⁺ | ¹²⁷Ba | β⁺ | Activation/Synth. | R. |
| ¹²⁸La | 57 | 128 | No | ~5.18 min | β⁺ | ¹²⁸Ba | β⁺ | Activation/Synth. | R. |
| ¹²⁹La | 57 | 129 | No | ~11.6 min | β⁺ | ¹²⁹Ba | β⁺ | Activation/Synth. | R. |
| ¹³⁰La | 57 | 130 | No | ~8.7 min | β⁺ | ¹³⁰Ba | β⁺ | Activation/Synth. | R. |
| ¹³¹La | 57 | 131 | No | ~59 min | β⁺ | ¹³¹Ba | β⁺ | Activation/Synth. | R. |
| ¹³²La | 57 | 132 | No | 4.59 h | β⁺ | ¹³²Ba | β⁺ (+γ) | Cyclotron | M/R: emerging PET surrogate for ²²⁵Ac radiotherapeutics. |
| ¹³³La | 57 | 133 | No | 3.912 h | β⁺ / EC | ¹³³Ba | β⁺ (+γ) | Cyclotron | M/R: PET theranostic studies (lanthanum “match” to Ac³⁺ chemistry). |
| ¹³⁴La | 57 | 134 | No | ~6.45 min | β⁺ | ¹³⁴Ba | β⁺ | Activation/Synth. | R; short‑lived PET tracer research. |
| ¹³⁵La | 57 | 135 | No | 18.91 h | β⁺ | ¹³⁵Ba | β⁺ (+γ) | Activation/Synth. | R/theranostic pair with ¹³²La. |
| ¹³⁶La | 57 | 136 | No | ~9.87 min | β⁺ | ¹³⁶Ba | β⁺ | Activation/Synth. | R. |
| ¹³⁷La | 57 | 137 | No | ~6×10⁴ y | EC (100%) | ¹³⁷Ba | X‑rays/γ (EC) | Synthetic | Long‑lived; not primordial. |
| ¹³⁸La | 57 | 138 | No (primordial) | ≈1.03×10¹¹ y | β⁺ (≈65.5%), β⁻ (≈34.5%) | ¹³⁸Ba / ¹³⁸Ce | β⁺/β⁻ + γ 789, 1436 keV | Natural (trace 0.089–0.090%) | Intrinsic radioactivity in LaBr₃/LaCl₃ scintillators (energy‑calibration lines); geochemical interest. |
| ¹³⁹La | 57 | 139 | Yes | Stable | — | — | — | Natural (99.911%) | Defines natural La; parent in LaBr₃(Ce) crystals. |
| ¹⁴⁰La | 57 | 140 | No | 40.289 h (≈1.678 d) | β⁻ (100%) | ¹⁴⁰Ce | β⁻ + γ (notably ~487 & 1596 keV) | Fission product (from ¹⁴⁰Ba) | Forensics chronometer (¹⁴⁰Ba/¹⁴⁰La); NIST SRM exists. |
| ¹⁴¹La | 57 | 141 | No | ~3.92 h | β⁻ | ¹⁴¹Ce | β⁻ + γ | Fission product | R (reactor studies). |
| ¹⁴²La | 57 | 142 | No | ~91.1 min | β⁻ | ¹⁴²Ce | β⁻ + γ | Fission product | R. |
| ¹⁴³La | 57 | 143 | No | ~14.2 min | β⁻ | ¹⁴³Ce | β⁻ + γ | Fission product | R. |
| ¹⁴⁴La | 57 | 144 | No | ~44.0 s | β⁻ | ¹⁴⁴Ce | β⁻ | Fission product | R. |
| ¹⁴⁵La | 57 | 145 | No | ~24.8 s | β⁻ | ¹⁴⁵Ce | β⁻ | Fission product | R. |
| ¹⁴⁶La | 57 | 146 | No | ~9.9 s | β⁻ | ¹⁴⁶Ce | β⁻ | Fission product | R. |
| ¹⁴⁷La | 57 | 147 | No | 4.026 s | β⁻ (99.96%), β⁻,n (0.041%) | ¹⁴⁷Ce / ¹⁴⁶Ce | β⁻; β‑delayed n | Neutron‑rich FP | R. |
| ¹⁴⁸La | 57 | 148 | No | 1.414 s | β⁻ (99.82%), β⁻,n (0.18%) | ¹⁴⁸Ce / ¹⁴⁷Ce | β⁻; β‑delayed n | Neutron‑rich FP | R. |
| ¹⁴⁹La | 57 | 149 | No | 1.071 s | β⁻ (98.57%), β⁻,n (1.43%) | ¹⁴⁹Ce / ¹⁴⁸Ce | β⁻; β‑delayed n | Neutron‑rich FP | R. |
| ¹⁵⁰La | 57 | 150 | No | 504 ms | β⁻ (97.3%), β⁻,n (2.7%) | ¹⁵⁰Ce / ¹⁴⁹Ce | β⁻; β‑delayed n | In‑flight fission | R. |
| ¹⁵¹La | 57 | 151 | No | ~300 ns | β⁻ (prompt) | ¹⁵¹Ce | β⁻ | In‑flight fission | R; very short‑lived. |
| ¹⁵²La | 57 | 152 | No | ~287 ms | β⁻ | ¹⁵²Ce | β⁻ | In‑flight fission | R; mass measured recently. |
| ¹⁵³La | 57 | 153 | No | ~245 ms | β⁻ | ¹⁵³Ce | β⁻ | In‑flight fission | R; mass measured recently. |
| ¹⁵⁴La | 57 | 154 | No | ~161 ms | β⁻ | ¹⁵⁴Ce | β⁻ | In‑flight fission | R. |
| ¹⁵⁵La | 57 | 155 | No | ~101 ms | β⁻ | ¹⁵⁵Ce | β⁻ | In‑flight fission | R. |
| ¹⁵⁶La | 57 | 156 | No | ~84 ms (±) | β⁻ | ¹⁵⁶Ce | β⁻ | In‑flight fission | R. |
| ¹⁵⁷La | 57 | 157 | No | ~30 ms (#) | β⁻ | ¹⁵⁷Ce | β⁻ | In‑flight fission | R; very exotic. |
Natural isotopic composition (terrestrial La). ~99.911% ¹³⁹La (stable) and ~0.089% ¹³⁸La (primordial radionuclide, t½≈1.06×10¹¹ y).
Key isomers (selected, applied relevance)
- ¹³²ᵐLa — 24.3 min, IT (→ ¹³²La). Longest‑lived La isomer; appears in PET production chains.
- ¹³⁶ᵐ¹La — 114 ms, IT (→ ¹³⁶La); ¹³⁶ᵐ²La — 187 ns. Nuclear‑structure interest.
Applied & research highlights (La)
- PET theranostics (R/M).¹³²La (4.59 h, β⁺) and ¹³³La (3.91 h, β⁺/EC) are being developed as PET surrogates for ²²⁵Ac targeted α‑therapy because La³⁺ ↔ Ac³⁺ share close ionic radii/chemistry; cyclotron production and in‑vivo mouse PET have been demonstrated.
- Intrinsic calibration lines.¹³⁸La within LaBr₃(Ce)/LaCl₃(Ce) emits ~789 keV (β⁻ branch to ¹³⁸Ce) and ~1436 keV (EC branch to ¹³⁸Ba) γ rays; widely used for self‑calibration and background modeling in fast scintillators.
- Fission forensics.¹⁴⁰Ba (12.75 d) → ¹⁴⁰La (40.289 h) pair acts as a chronometer for recent fission; LNHB provides the adopted ¹⁴⁰La half‑life (1.6786 d) and decay scheme; NIST has an SRM of Ba‑140/La‑140.
- Frontier nuclides.Very neutron‑rich ¹⁵²–¹⁵⁷La have sub‑second half‑lives; new precision mass measurements were reported via Penning‑trap techniques (JYFLTRAP).
Totals — Lanthanum (Z = 57)
- Ground‑state isotopes listed42 (A = 116–157).
- Stable ground states1 (¹³⁹La).
- Unstable ground states41 (includes primordial ¹³⁸La).
(Counts and range reflect the current evaluated tables; very exotic A≥151 values have larger uncertainties.)
Running cumulative totals (through La): add +42 total / +1 stable / +41 unstable to your prior ledger (after Ba we were at ≥1639 total, 168 stable, ≥1471 unstable) → ≥1681 total, 169 stable, ≥1512 unstable.
Source backbone (load‑bearing)
- Evaluated half‑lives, decay modes, daughters (most rows)Isotopes of lanthanum consolidated table.
- Very exotic A=152–157 (sub‑second region)updated table + recent Penning‑trap mass news (JYFLTRAP).
- Natural isotopic composition / primordial ¹³⁸LaCIAAW element page.
- ¹³⁸La γ lines & self‑activity in LaBr₃/LaCl₃PNNL report; INL study; LaCl₃ detector characterization.
- ¹⁴⁰La half‑life & decay scheme; forensic chronometerLNHB data sheet; precision Ge‑detector measurement; forensic methodology.
- Theranostic PET (¹³²/¹³³La)peer‑reviewed PET studies & reviews.
Next element: Cerium — Ce (Z = 58).
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