Isotopes of astatine

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Isotopes of astatine  (85At)
Main isotopes [1] Decay
Isotope abun­dance half-life (t1/2) mode pro­duct
207At synth 1.81 h β+ 90% 207Po
α 10% 203Bi
208Atsynth1.63 hβ+99.5% 208Po
α0.55% 204Bi
209Atsynth5.41 hβ+96.1% 209Po
α3.9% 205Bi
210Atsynth8.1 hβ+99.8% 210Po
α0.175% 206Bi
211Atsynth7.214 h ε 58.2% 211Po
α41.8% 207Bi

Astatine (85At) has 41 known isotopes, all of which are radioactive, whose mass numbers range from 188 to 229 except 189; they are accompanied by almost as many metastable excited states. The longest-lived isotope is 210At, which has a half-life of 8.1 hours, followed by the medically useful 211At, with a half-life of 7.214 hours. The longest-lived isomer is 202m1At with a half-life of just over 3 minutes. However, the longest-lived isotope existing in naturally occurring decay chains is 219At with a half-life of only 56 seconds.

Contents

List of isotopes


Nuclide
[n 1]
Z N Isotopic mass (Da) [2]
[n 2] [n 3]
Half-life [1]
Decay
mode
[1]
[n 4]
Daughter
isotope

[n 5]
Spin and
parity [1]
[n 6] [n 7]
Isotopic
abundance
Excitation energy [n 7]
188At [3] 85103190+350
−80
 μs
α (~50%)184Bi
p (~50%)187Po
190At [4] 851051.0+1.4
−0.4
 ms
α186Bi(10−)
191At85106191.004148(17)2.1(8) msα187Bi1/2+
191mAt58(20) keV2.2(4) msα187Bi(7/2−)
192At85107192.003141(3)11.5(6) msα188Bi3+#
192mAt [n 8] 0(40) keV88(6) msα188mBi(9−, 10−)
193At85108192.999928(23)29(5) msα189Bi1/2+
193m1At [n 8] 8(9) keV21(5) msα189m1Bi7/2−
193m2At42(9) keV28(4) msIT (76%)193At13/2+
α (24%)189m2Bi
194At85109193.999231(25)286(7) msα (91.7%#)190Bi(5−)
β+ (8.3%#)194Po
β+, SF (0.032%#)(various)
194mAt [n 8] −20(40) keV323(7) msα (91.7%#)190Bi10−
β+ (8.3%#)194Po
β+, SF (0.032%#)(various)
195At85110194.996274(10)290(20) msα191mBi1/2+
β+ ?195Po
195mAt29(7) keV143(3) msα (88%)191Bi7/2-
IT (12%)195At
β+?195Po
196At85111195.99580(3)377(4) msα (97.5%)192Bi(3+)
β+ (2.5%)196Po
β+, SF (0.009%)(various)
196m1At [n 8] −40(40) keV20# msα192mBi10−#
196m2At157.9(1) keV11(2) μsIT196At(5+)
197At85112196.993177(9)388.2(56) msα (96.1%)193Bi9/2−
β+ (3.9%)197Po
197m1At45(8) keV2.0(2) sα193m1Bi1/2+
IT (<0.004%)197At
β+?197Po
197m2At310.7(2) keV1.3(2) μsIT197At13/2+
198At85113197.992798(5)4.47(5) sα (97%)194Bi3+
β+ (3%)198Po
198mAt266.6(27) keV1.23(5) sα (93%)10−
β+ ?198Po
IT ?198Po
199At85114198.990528(6)7.02(12) sα (89%)195Bi9/2−
β+ (11%)199Po
199m1At244.0(10) keV273(9) msIT (99%)1/2+
α (1%)195Bi
199m2At572.9(1) keV70(20) nsIT13/2+
199m3At2293.4(5) keV800(50) nsIT(29/2+)
200At85115199.990351(26)43.2(9) sα (52%)196Bi(3+)
β+ (48%)200Po
200m1At112.9(29) keV47(1) sβ+ (57%)200Po(7+)
α (43%)196Bi
IT ?200At
200m2At343.8(30) keV8.0(21) sIT ?200At(10−)
α (10.5%)196Bi
β+ ?200Po
201At85116200.988417(9)85.2(16) sα (71%)197Bi9/2−
β+ (29%)201Po
201m1At459(1) keV45(3) msIT1/2+
201m2At459(1) keV3.39(9) μsIT29/2+
202At85117201.988626(30)184(1) sβ+ (88%)202Po3+
α (12%)198Bi
202m1At190(40) keV182(2) sβ+ (91.5%)202Po7+
α (8.5%)198Bi
IT ?202At
202m2At590(40) keV460(50) msIT (99.904%)202At10−
α (0.096%)198Bi
IT ?202At
203At85118202.986943(11)7.4(2) minβ+ (69%)203Po9/2−
α (31%)199Bi
203m1At683.4(3) keV3.5(6) msIT1/2+
203m2At2330.1(4) keV9.77(21) μsIT29/2+
204At85119203.987251(24)9.12(11) minβ+ (96.2%)204Po7+
α (3.8%)200Bi
204mAt587.30(20) keV108(10) msIT204At10−
205At85120204.986061(13)26.9(8) minβ+ (90%)205Po9/2−
α (10%)201Bi
205mAt2339.64(23) keV7.76(14) μsIT205At29/2+
206At85121205.986646(15)30.6(8) minβ+ (99.1%)206Po(6)+
α (0.9%)202Bi
206mAt810(2) keV813(21) nsIT206At(10)−
207At85122206.985800(13)1.81(3) hβ+ (~90%)207Po9/2−
α (~10%)203Bi
207mAt2117.3(6) keV108(2) nsIT207At25/2+
208At85123207.986613(10)1.63(3) hβ+ (99.45%)208Po6+
α (0.55%)204Bi
208mAt2276.4(18) keV1.5(2) μsIT208At16-
209At85124208.986169(5)5.42(5) hβ+ (96.1%)209Po9/2−
α (3.9%)205Bi
209mAt2429.32(22) keV916(10) nsIT209At29/2+
210At85125209.987147(8)8.1(4) hβ+ (99.825%)210Po(5)+
α (0.175%)206Bi
210m1At2549.6(2) keV482(6) nsIT210At(15)−
210m2At4027.7(2) keV5.66(7) μsIT210At(19)+
211At85126210.9874962(29)7.214(7) h EC (58.2%)211Po9/2−
α (41.8%)207Bi
211mAt4814.5(5) keV4.23(7) μsIT211At(39/2-)
212At85127211.9907373(26)314(3) msα [n 9] 208Bi(1−)
212m1At222.9(9) keV119(3) msα208Bi(9−)
212m2At4771.4(15) keV152(5) μsIT212At(25−)
213At85128212.992937(5)125(6) nsα [n 10] 209Bi9/2−
213m1At1358(23) keV110(17) nsIT213At25/2-#
213m2At2998(27) keV45(4) μsIT213At49/2+#
214At85129213.996372(4)558(10) nsα210Bi1−
214m1At59(9) keV265(30) nsα210Bi
214m2At232(5) keV760(15) nsα210mBi [7] 9−
215At85130214.998651(7)37(3) μsα211Bi9/2−Trace [n 11]
216At85131216.002423(4)300(30) μsα [n 12] 212Bi1−
216mAt161(11) keV100# μsα212m1Bi [9] 9−#
217At85132217.004718(5)32.6(3) msα (99.992%)213Bi9/2−Trace [n 13]
β (0.008%)217Rn
218At85133218.008696(12)1.28(6) sα (~100%)214Bi(2−,3−)Trace [n 14]
β (?)218Rn
219At85134219.011161(3)56(3) sα (93.6%)215Bi(9/2−)Trace [n 11]
β (6.4%)219Rn
220At85135220.015433(15)3.71(4) minβ (92%)220Rn3(−#)
α (8%)216Bi
221At85136221.018017(15)2.3(2) minβ221Rn3/2−#
222At85137222.022494(17)54(10) sβ222Rn
223At85138223.025151(15)50(7) sβ223Rn3/2−#
224At85139224.029749(24)2.5 +/- 1.5 minβ224Rn2+#
225At85140225.03253(32)#3# s (>300 ns)β ?225Rn1/2+#
226At85141226.03721(32)#7# min (>300 ns)β ?226Rn2+#
227At85142227.04018(32)#5# s (>300 ns)β ?227Rn1/2+#
228At85143228.04496(43)#1# min (>300 ns)β ?228Rn3+#
229At85144229.04819(43)#1# s (>300 ns)β ?229Rn1/2+#
This table header & footer:
  1. mAt  Excited nuclear isomer.
  2. ()  Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. #  Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. Modes of decay:
    EC: Electron capture
    IT: Isomeric transition
  5. Bold italics symbol as daughter  Daughter product is nearly stable.
  6. () spin value  Indicates spin with weak assignment arguments.
  7. 1 2 #  Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  8. 1 2 3 4 Order of ground state and isomer is uncertain.
  9. Theoretically capable of β+ decay to 212Po or β decay to 212Rn; the branching ratios are expected to be <3×10−2% and <2×10−6% (partial half-lives >17.4 min and >182 d) respectively. [5]
  10. Theoretically capable of electron capture to 213Po; the branching ratio is expected to be <2.5×10−12% (partial half-life >57.9 d). [6]
  11. 1 2 Intermediate decay product of 235U
  12. Theoretically capable of electron capture to 216Po or β decay to 216Rn; the branching ratios are expected to be <3×10−7% and <6×10−3% (partial half-lives >1.2 d and >5.0 s) respectively. [8]
  13. Intermediate decay product of 237Np
  14. Intermediate decay product of 238U

Alpha decay

Alpha decay characteristics for astatine isotopes, with all nuclear data from NUBASE2020. [1] [a]
Mass number Mass excess Mass excess of daughterEnergy of alpha decayHalf-lifeProbability of alpha decayAlpha decay half-life
195−3.470 MeV−10.814 MeV7.344 MeV0.29 s~100%0.29 s
196−3.910 MeV−11.105 MeV7.195 MeV0.377 s97.5%0.39 s
197−6.355 MeV−13.460 MeV7.105 MeV0.388 s96.1%0.40 s
198−6.709 MeV−13.598 MeV6.889 MeV4.47 s97%4.6 s
199−8.823 MeV−15.601 MeV6.778 MeV7.0 s89%7.9 s
200−8.988 MeV−15.584 MeV6.596 MeV43.2 s52%83 s
201−10.789 MeV−17.262 MeV6.473 MeV85.2 s71%2.0 min
202−10.595 MeV−16.949 MeV6.354 MeV184 s12%2.6 min
203−12.163 MeV−18.373 MeV6.210 MeV7.4 min31%2.4 min
204−11.875 MeV−17.946 MeV6.071 MeV9.1 min3.8%4.0 h
205−12.985 MeV−19.004 MeV6.039 MeV26.9 min10%4.5 h
206−12.439 MeV−18.326 MeV5.887 MeV30.6 min0.90%2.4 d
207−13.227 MeV−19.100 MeV5.873 MeV1.81 h~10%18 h
208−12.470 MeV−18.221 MeV5.751 MeV1.63 h0.55%12.3 d
209−12.884 MeV−18.641 MeV5.757 MeV5.42 h3.9%5.8 d
210−11.972 MeV−17.603 MeV5.631 MeV8.1 h0.175%193 d
211−11.647 MeV−17.630 MeV5.983 MeV7.214 h41.80%17 h
212−8.628 MeV−16.445 MeV7.817 MeV0.314 s0.31 s
213−6.580 MeV−15.834 MeV9.254 MeV125 ns100%125 ns
214−3.379 MeV−12.367 MeV8.988 MeV0.56 μs100%0.56 μs
215−1.257 MeV−9.434 MeV8.177 MeV37 μs100%37 μs
2162.257 MeV−5.693 MeV7.950 MeV0.3 ms100%0.3 ms
2174.395 MeV−2.807 MeV7.202 MeV32.6 ms99.992%33 ms
2188.100 MeV1.224 MeV6.876 MeV1.28 s~100%1.28 s
21910.396 MeV4.054 MeV6.342 MeV56 s93.6%60 s
22014.376 MeV8.299 MeV6.077 MeV3.71 min8%46 min
22116.783 MeV11.155 MeV5.628 MeV2.3 min-

Alpha decay energy follows the same trend as for other heavy elements. [10] The lighter astatine isotopes have quite high decay energies, which become lower as more neutrons are added, reaching a minimum at 125 neutrons (astatine-210), even though 126 (astatine-211) is the magic number. The decay energies increase much more steeply, though, on the next two steps, reaching a high at 128 neutrons where the alpha-decay product would have the magic number of 126. Here this is astatine-213, releasing the highest energy and having the shortest life (125 ns) of all the isotopes. The energy then declines again, and alpha lifetimes increase quickly, no long-lived astatine isotope exists; this happens due to the increasing role of beta decay. [10] This decay mode is especially important for astatine: as early as 1950, it was postulated that the element has no beta-stable isotopes (i.e. ones that do not undergo beta decay at all), [11] though nuclear mass measurements reveal that 215At is in fact beta-stable, as it has the lowest mass of all isobars with A = 215. [1] A beta decay mode has been found for all other astatine isotopes except for 212-216At and their isomers. [1] Among other isotopes, if they do not undergo alpha decay: astatine-210 and the lighter isotopes decay by electron capture or positron emission, 211 by electron capture only, and astatine-217 and heavier isotopes undergo β- decay. Astatine-212, 214, and 216 should be able to decay either way.

See also

Daughter products other than astatine

Notes

  1. In the table, under the words "mass excess", the energy equivalents are given rather than the real mass excesses; "mass excess of daughter" stands for the energy equivalent of the mass excess sum of the daughter of the isotope and the alpha particle; "alpha decay half-life" refers to the half-life if decay modes other than alpha are omitted.

References

  1. 1 2 3 4 5 6 7 Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3) 030001. doi:10.1088/1674-1137/abddae.
  2. Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3) 030003. doi:10.1088/1674-1137/abddaf.
  3. Kokkonen, Henna; Auranen, Kalle; Siwach, Pooja; Arumugam, Paramasivan; Briscoe, Andrew D.; Eeckhaudt, Sarah; Ferreira, Lidia S.; Grahn, Tuomas; Greenlees, Paul T.; Jones, Pete; Julin, Rauno; Juutinen, Sakari; Leino, Matti; Leppänen, Ari-Pekka; Maglione, Enrico; Nyman, Markus; Page, Robert D.; Pakarinen, Janne; Rahkila, Panu; Sarén, Jan; Scholey, Catherine; Sorri, Juha; Uusitalo, Juha; Venhart, Martin (29 May 2025). "New proton emitter 188At implies an interaction unprecedented in heavy nuclei". Nature Communications. 16 (1). doi:10.1038/s41467-025-60259-6. PMC   12122845 .
  4. Kokkonen, H.; Auranen, K.; Uusitalo, J.; Eeckhaudt, S.; Grahn, T.; Greenlees, P. T.; Jones, P.; Julin, R.; Juutinen, S.; Leino, M.; Leppänen, A.-P.; Nyman, M.; Pakarinen, J.; Rahkila, P.; Sarén, J.; Scholey, C.; Sorri, J.; Venhart, M. (20 June 2023). "Properties of the new α -decaying isotope At 190". Physical Review C. 107 (6). doi:10.1103/PhysRevC.107.064312.
  5. "Adopted Levels for 212At" (PDF). NNDC Chart of Nuclides.
  6. "Adopted Levels for 213At" (PDF). NNDC Chart of Nuclides.
  7. "214At α decay (760 ns)" (PDF). NNDC Chart of Nuclides.
  8. "Adopted Levels for 216At" (PDF). NNDC Chart of Nuclides.
  9. "216At α decay: J=9" (PDF). NNDC Chart of Nuclides.
  10. 1 2 Lavrukhina & Pozdnyakov 1966, p. 232.
  11. Rankama, Kalervo (1956). Isotope geology (2nd ed.). Pergamon Press. p. 403. ISBN   978-0-470-70800-2.{{cite book}}: ISBN / Date incompatibility (help)