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Polonium (Po) has 33 isotopes, all of which are radioactive. They have atomic masses that range from 188u to 220u. 210Po is the most widely available. 209Po (half-life 103 years) and 208Po (half-life 2.9 years) can be made through the alpha, proton, or deuteron bombardment of lead or bismuth in a cyclotron.

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210Po

210Po is an alpha emitter that has a half-life of 138.376 days; it decays directly to its daughter isotope 206Pb. A milligram of 210Po emits as many alpha particles per second as 4.215 grams of 226Ra. A few curies (1 curie equals 37 gigabecquerels) of 210Po emit a blue glow which is caused by excitation of surrounding air. A single gram of 210Po generates 140 watts of power.[1] Because it emits many alpha particles, which are stopped within a very short distance in dense media and release their energy, 210Po has been used as a lightweight heat source to power thermoelectric cells in artificial satellites; for instance, 210Po heat source was also used in each of the Lunokhod rovers deployed on the surface of the Moon, to keep their internal components warm during the lunar nights.[2] Some anti-static brushes contain up to 500 microcuries of 210Po as a source of charged particles for neutralizing static electricity in materials like photographic film.[3] 210Po was used to kill Russian dissident and ex-FSB officer Alexander V. Litvinenko in 2006.[4]

The majority of the time 210Po decays by emission of an alpha particle only, not by emission of an alpha particle and a gamma ray. About one in 100,000 decays results in the emission of a gamma ray.[5] This low gamma ray production rate makes it more difficult to find and identify this isotope. Rather than gamma ray spectroscopy, alpha spectroscopy is the best method of measuring this isotope.

Former names of isotopes

Isotopes of polonium occurring within the radioactive disintegration chains of actinium, radium and thorium were known as:

  • radium F : 210Po
  • actinium CI : 211Po
  • thorium CI : 212Po
  • radium CI : 214Po
  • actinium A : 215Po
  • thorium A : 216Po
  • radium A : 218Po

also found in sper,

Table

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life nuclear
spin
representative
isotopic
composition
(mole fraction)
range of natural
variation
(mole fraction)
excitation energy
188Po 84 104 187.999422(21) 430(180) µs [0.40(+20-15) ms] 0+
189Po 84 105 188.998481(24) 5(1) ms 3/2-#
190Po 84 106 189.995101(14) 2.46(5) ms 0+
191Po 84 107 190.994574(12) 22(1) ms 3/2-#
191mPo 130(21) keV 93(3) ms (13/2+)
192Po 84 108 191.991335(13) 32.2(3) ms 0+
192mPo 2600(500)# keV ~1 µs 12+#
193Po 84 109 192.99103(4) 420(40) ms [370(+46-40) ms] 3/2-#
193mPo 100(30)# keV 240(10) ms [243(+11-10) ms] (13/2+)
194Po 84 110 193.988186(13) 0.392(4) s 0+
194mPo 2525(2) keV 15(2) µs (11-)
195Po 84 111 194.98811(4) 4.64(9) s 3/2-#
195mPo 110(50) keV 1.92(2) s 13/2+#
196Po 84 112 195.985535(14) 5.56(12) s 0+
196mPo 2490.5(17) keV 850(90) ns (11-)
197Po 84 113 196.98566(5) 53.6(10) s (3/2-)
197mPo 230(80)# keV 25.8(1) s (13/2+)
198Po 84 114 197.983389(19) 1.77(3) min 0+
198m1Po 2565.92(20) keV 200(20) ns 11-
198m2Po 2691.86(20) keV 750(50) ns 12+
199Po 84 115 198.983666(25) 5.48(16) min (3/2-)
199mPo 312.0(28) keV 4.17(4) min 13/2+
200Po 84 116 199.981799(15) 11.5(1) min 0+
201Po 84 117 200.982260(6) 15.3(2) min 3/2-
201mPo 424.1(24) keV 8.9(2) min 13/2+
202Po 84 118 201.980758(16) 44.7(5) min 0+
202mPo 2626.7(7) keV >200 ns 11-
203Po 84 119 202.981420(28) 36.7(5) min 5/2-
203m1Po 641.49(17) keV 45(2) s 13/2+
203m2Po 2158.5(6) keV >200 ns
204Po 84 120 203.980318(12) 3.53(2) h 0+
205Po 84 121 204.981203(21) 1.66(2) h 5/2-
205m1Po 143.166(17) keV 310(60) ns 1/2-
205m2Po 880.30(4) keV 645 µs 13/2+
205m3Po 1461.21(21) keV 57.4(9) ms 19/2-
205m4Po 3087.2(4) keV 115(10) ns 29/2-
206Po 84 122 205.980481(9) 8.8(1) d 0+
206m1Po 1585.85(11) keV 222(10) ns (8+)#
206m2Po 2262.22(14) keV 1.05(6) µs (9-)#
207Po 84 123 206.981593(7) 5.80(2) h 5/2-
207m1Po 68.573(14) keV 205(10) ns 1/2-
207m2Po 1115.073(16) keV 49(4) µs 13/2+
207m3Po 1383.15(6) keV 2.79(8) s 19/2-
208Po 84 124 207.9812457(19) 2.898(2) a 0+
209Po 84 125 208.9824304(20) 102(5) a 1/2-
210Po 84 126 209.9828737(13) 138.376(2) d 0+
210mPo 5057.61(4) keV 263(5) ns 16+
211Po 84 127 210.9866532(14) 0.516(3) s 9/2+
211m1Po 1462(5) keV 25.2(6) s (25/2+)
211m2Po 2135.7(9) keV 243(21) ns (31/2-)
211m3Po 4873.3(17) keV 2.8(7) µs (43/2+)
212Po 84 128 211.9888680(13) 299(2) ns 0+
212mPo 2911(12) keV 45.1(6) s (18+)
213Po 84 129 212.992857(3) 3.65(4) µs 9/2+
214Po 84 130 213.9952014(16) 164.3(20) µs 0+
215Po 84 131 214.9994200(27) 1.781(4) ms 9/2+
216Po 84 132 216.0019150(24) 0.145(2) s 0+
217Po 84 133 217.006335(7) 1.47(5) s 5/2+#
218Po 84 134 218.0089730(26) 3.10(1) min 0+
219Po 84 135 219.01374(39)# 2# min [>300 ns] 7/2+#
220Po 84 136 220.01660(39)# 40# s [>300 ns] 0+
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Notes

  • Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
  • Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.
  • Half-life abbreviations are a=annum(year), d=day, min=minute, s=second, ms=millisecond, µs=microsecond, ns=nanosecond.
  • A superscripted m (or m2, etc.) refers to an isomer of that particular isotope.

References

  1. ^ Polonium, Argonne National Laboratory
  2. ^ Andrew Wilson, Solar System Log, (London: Jane's Publishing Company Ltd, 1987), p. 64.
  3. ^ Staticmaster
  4. ^ Radiation Poisoning Killed Ex-Russian Spy
  5. ^ 210PO A DECAY
Isotopes of bismuth Isotopes of polonium Isotopes of astatine
Index to isotope pages · Table of nuclides

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