## Master Isotope Table + γ & Kα (Batch 5: Z = 81–100)
| Z | Elem | Known | Stable | Unstable | Pred. | Gap | Nuclear γ (keV) | f(γ) (Hz) | Kα₁ (keV) | f(Kα₁) (Hz) | Context |
|---:|:---:|---:|---:|---:|---:|---:|---:|---:|---:|---:|---|
| 81 | Tl | 39 | 2 | 37 | 93 | 54 | 2614.5 | 6.32×10^20 | 72.871 | 1.76×10^19 | ²⁰⁸Tl (Th chain) + XRF |
| 82 | Pb | 43 | 4 | 39 | 102 | 59 | 351.9 / 46.5 | 8.51×10^19 / 1.12×10^19 | 74.969 | 1.81×10^19 | ²¹⁴Pb, ²¹⁰Pb; XRF |
| 83 | Bi | 41 | 0 | 41 | 97 | 56 | 609.3 / 1120.3 / 1764.5 | 1.47×10^20 / 2.71×10^20 / 4.27×10^20 | 77.107 | 1.86×10^19 | ²¹⁴Bi γs + XRF |
| 84 | Po | 42 | 0 | 42 | 100 | 58 | — | — | 79.292 | 1.92×10^19 | α-emitter, no strong γ; XRF |
| 85 | At | 39 | 0 | 39 | 93 | 54 | — | — | 81.58 | 1.97×10^19 | Short-lived α; XRF theor. |
| 86 | Rn | 39 | 0 | 39 | 93 | 54 | 609.3 / 1764.5 | 1.47×10^20 / 4.27×10^20 | 83.9 | 2.03×10^19 | γs via daughters; noble gas |
| 87 | Fr | 34 | 0 | 34 | 81 | 47 | — | — | 86.3 | 2.09×10^19 | Short-lived; XRF theor. |
| 88 | Ra | 34 | 0 | 34 | 81 | 47 | 186.2 | 4.50×10^19 | 88.8 | 2.15×10^19 | ²²⁶Ra tracer + XRF |
| 89 | Ac | 33 | 0 | 33 | 78 | 45 | 911.2 | 2.20×10^20 | 91.4 | 2.21×10^19 | ²²⁸Ac fission chain + XRF |
| 90 | Th | 31 | 1 | 30 | 74 | 43 | 238.6 / 2614.5 | 5.76×10^19 / 6.32×10^20 | 94.0 | 2.27×10^19 | Th-series γs + XRF |
| 91 | Pa | 29 | 0 | 29 | 69 | 40 | 312.0 | 7.53×10^19 | 96.7 | 2.34×10^19 | ²³³Pa intermediate + XRF |
| 92 | U | 28 | 0 | 28 | 66 | 38 | 1001.0 | 2.42×10^20 | 98.439 | 2.38×10^19 | ²³⁴mPa (U-series) + XRF |
| 93 | Np | 20 | 0 | 20 | 47 | 27 | 106.1 | 2.56×10^19 | (theor.) | — | ²³⁷Np γ; Kα theor. |
| 94 | Pu | 20 | 0 | 20 | 47 | 27 | 375.0 / 51.6 | 9.07×10^19 / 1.25×10^19 | (theor.) | — | ²³⁹Pu (fuel); Kα theor. |
| 95 | Am | 17 | 0 | 17 | 40 | 23 | 59.5 | 1.44×10^19 | (theor.) | — | ²⁴¹Am detectors; Kα theor. |
| 96 | Cm | 19 | 0 | 19 | 45 | 26 | 333.0 | 8.05×10^19 | (theor.) | — | Cm isotopes; Kα theor. |
| 97 | Bk | 21 | 0 | 21 | 50 | 29 | 225.0 | 5.43×10^19 | (theor.) | — | ²⁴⁹Bk research; Kα theor. |
| 98 | Cf | 20 | 0 | 20 | 47 | 27 | 388.0 | 9.45×10^19 | (theor.) | — | ²⁵²Cf neutron source; Kα theor. |
| 99 | Es | 18 | 0 | 18 | 43 | 25 | 300.0 | 7.25×10^19 | (theor.) | — | ²⁵³Es research; Kα theor. |
| 100 | Fm | 19 | 0 | 19 | 45 | 26 | 125.0 | 3.02×10^19 | (theor.) | — | ²⁵⁵Fm lab-only; Kα theor. |
Say “Next” and I’ll deliver Batch 6 (Z = 101–118) to complete the full table.
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