Isotopes of polonium

Polonium (Po) has 33 isotopes, all of which are radioactive, with between 186 and 227 nucleons. ²¹⁰Po with a half-life of 138.376 days has the longest half-life of naturally occurring polonium. ²⁰⁹Po with a half-life of 125 years has the longest half-life of all isotopes of polonium. ²⁰⁹Po and ²⁰⁸Po (half-life 2.9 years) can be made through the alpha, proton, or deuteron bombardment of lead or bismuth in a cyclotron.

Polonium-210

²¹⁰Po is an alpha emitter that has a half-life of 138.376 days; it decays directly to stable ²⁰⁶Pb. A milligram of ²¹⁰Po emits as many alpha particles per second as 5 grams of ²²⁶Ra.^[1] A few curies (1 curie equals 37 gigabecquerels) of ²¹⁰Po emit a blue glow caused by excitation of surrounding air. A single gram of ²¹⁰Po generates 140 watts of power.^[2] 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, a ²¹⁰Po heat source was also in each of the Lunokhod rovers deployed on the surface of the Moon, to keep their internal components warm during the lunar nights.^[3] Some anti-static brushes, used for neutralizing static electricity on materials like photographic film, contain a few microcuries of ²¹⁰Po as a source of charged particles.^{[4] 210}Po is also used in initiators for atomic bombs through the (α,n) reaction with beryllium.

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.

²¹⁰Po occurs in minute amounts in nature, where it is an intermediate isotope in the uranium series (also known as the uranium series) decay chain. It is generated via beta decay from ²¹⁰Bi.

²¹⁰Po is extremely toxic, with one microgram being enough to kill the average adult (250,000 times more toxic than hydrogen cyanide by weight).^{[6] 210}Po was used to kill Russian dissident and ex-FSB officer Alexander V. Litvinenko in 2006,^[7] and was suspected as a possible cause of Yasser Arafat's death, following exhumation and analysis of his corpse in 2012–2013.^[8]

Table

nuclide symbol	historic name	Z(p) [9][10]	N(n) [9][10]	isotopic mass (u) [11]	half-life [11][12][13]	decay mode(s) [14][n 1]	daughter isotope(s) [n 2]	nuclear spin [11][12][13]	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	α (99.9%)	^186Pb	0+
						β^+ (.1%)	^190Bi
^191Po		84	107	190.994574(12)	22(1) ms	α	^187Pb	3/2−#
						β^+ (rare)	^191Bi
^191mPo		130(21) keV			93(3) ms			(13/2+)
^192Po		84	108	191.991335(13)	32.2(3) ms	α (99%)	^188Pb	0+
						β^+ (1%)	^192Bi
^192mPo		2600(500)# keV			~1 µs			12+#
^193Po		84	109	192.99103(4)	420(40) ms [370(+46−40) ms]	α	^189Pb	3/2−#
						β^+ (rare)	^193Bi
^193mPo		100(30)# keV			240(10) ms [243(+11−10) ms]	α	^189Pb	(13/2+)
						β^+ (rare)	^193Bi
^194Po		84	110	193.988186(13)	0.392(4) s	α	^190Pb	0+
						β^+ (rare)	^194Bi
^194mPo		2525(2) keV			15(2) µs			(11−)
^195Po		84	111	194.98811(4)	4.64(9) s	α (75%)	^191Pb	3/2−#
						β^+ (25%)	^195Bi
^195mPo		110(50) keV			1.92(2) s	α (90%)	^191Pb	13/2+#
						β^+ (10%)	^195Bi
						IT (.01%)	^195Po
^196Po		84	112	195.985535(14)	5.56(12) s	α (94%)	^192Pb	0+
						β^+ (6%)	^196Bi
^196mPo		2490.5(17) keV			850(90) ns			(11−)
^197Po		84	113	196.98566(5)	53.6(10) s	β^+ (54%)	^197Bi	(3/2−)
						α (44%)	^193Pb
^197mPo		230(80)# keV			25.8(1) s	α (84%)	^193Pb	(13/2+)
						β^+ (16%)	^197Bi
						IT (.01%)	^197Po
^198Po		84	114	197.983389(19)	1.77(3) min	α (57%)	^194Pb	0+
						β^+ (43%)	^198Bi
^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	β^+ (92.5%)	^199Bi	(3/2−)
						α (7.5%)	^195Pb
^199mPo		312.0(28) keV			4.17(4) min	β^+ (73.5%)	^199Bi	13/2+
						α (24%)	^195Pb
						IT (2.5%)	^199Po
^200Po		84	116	199.981799(15)	11.5(1) min	β^+ (88.8%)	^200Bi	0+
						α (11.1%)	^196Pb
^201Po		84	117	200.982260(6)	15.3(2) min	β^+ (98.4%)	^201Bi	3/2−
						α (1.6%)	^197Pb
^201mPo		424.1(24) keV			8.9(2) min	IT (56%)	^201Po	13/2+
						EC (41%)	^201Bi
						α (2.9%)	^197Pb
^202Po		84	118	201.980758(16)	44.7(5) min	β^+ (98%)	^202Bi	0+
						α (2%)	^198Pb
^202mPo		2626.7(7) keV			>200 ns			11−
^203Po		84	119	202.981420(28)	36.7(5) min	β^+ (99.89%)	^203Bi	5/2−
						α (.11%)	^199Pb
^203m1Po		641.49(17) keV			45(2) s	IT (99.96%)	^203Po	13/2+
						α (.04%)	^199Pb
^203m2Po		2158.5(6) keV			>200 ns
^204Po		84	120	203.980318(12)	3.53(2) h	β^+ (99.33%)	^204Bi	0+
						α (.66%)	^200Pb
^205Po		84	121	204.981203(21)	1.66(2) h	β^+ (99.96%)	^205Bi	5/2−
						α (.04%)	^201Pb
^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	IT	^205Po	19/2−
^205m4Po		3087.2(4) keV			115(10) ns			29/2−
^206Po		84	122	205.980481(9)	8.8(1) d	β^+ (94.55%)	^206Bi	0+
						α (5.45%)	^202Pb
^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	β^+ (99.97%)	^207Bi	5/2−
						α (.021%)	^203Pb
^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	IT	^207Po	19/2−
^208Po		84	124	207.9812457(19)	2.898(2) y	α (99.99%)	^204Pb	0+
						β^+ (.00277%)	^208Bi
^209Po		84	125	208.9824304(20)	125.2(3.3) y[15]	α (99.52%)	^205Pb	1/2−
						β^+ (.48%)	^209Bi
^210Po	Radium F	84	126	209.9828737(13)	138.376(2) d	α	^206Pb	0+	Trace[n 3]
^210mPo		5057.61(4) keV			263(5) ns			16+
^211Po	Actinium C'	84	127	210.9866532(14)	0.516(3) s	α	^207Pb	9/2+	Trace[n 4]
^211m1Po		1462(5) keV			25.2(6) s	α (99.98%)	^207Pb	(25/2+)
						IT (.016%)	^211Po
^211m2Po		2135.7(9) keV			243(21) ns			(31/2−)
^211m3Po		4873.3(17) keV			2.8(7) µs			(43/2+)
^212Po	Thorium C'	84	128	211.9888680(13)	299(2) ns	α	^208Pb	0+	Trace[n 5]
^212mPo		2911(12) keV			45.1(6) s	α (99.93%)	^208Pb	(18+)
						IT (.07%)	^212Po
^213Po		84	129	212.992857(3)	3.65(4) µs	α	^209Pb	9/2+
^214Po	Radium C'	84	130	213.9952014(16)	164.3(20) µs	α	^210Pb	0+	Trace[n 3]
^215Po	Actinium A	84	131	214.9994200(27)	1.781(4) ms	α (99.99%)	^211Pb	9/2+	Trace[n 4]
						β^− (2.3×10^−4%)	^215At
^216Po	Thorium A	84	132	216.0019150(24)	0.145(2) s	α	^212Pb	0+	Trace[n 5]
						β^−β^− (rare)	^216Rn
^217Po		84	133	217.006335(7)	1.47(5) s	α (95%)	^213Pb	5/2+#
						β^− (5%)	^217At
^218Po	Radium A	84	134	218.0089730(26)	3.10(1) min	α (99.98%)	^214Pb	0+	Trace[n 3]
						β^− (.02%)	^218At
^219Po		84	135	219.01374(39)#	2# min [>300 ns]			7/2+#
^220Po		84	136	220.01660(39)#	40# s [>300 ns]			0+

1. Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
2. Bold for stable isotopes, bold italics for nearly stable isotopes (half-life longer than the age of the universe)
3. Intermediate decay product of Uranium-238
4. Intermediate decay product of Uranium-235
5. Intermediate decay product of Thorium-232

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 y=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. C. R. Hammond. "The Elements" (PDF). Fermi National Accelerator Laboratory. p. 4-22.
2. "Polonium" (PDF). Argonne National Laboratory. Archived from the original (PDF) on 2012-03-10.
3. Andrew Wilson, Solar System Log, (London: Jane's Publishing Company Ltd, 1987), p. 64.
4. "Staticmaster Alpha Ionizing Brush". Company 7.
5. 210PO A DECAY Archived February 24, 2015, at the Wayback Machine.
6. Sublette, Carey. "Polonium Poisoning".
7. Cowell, Alan (November 24, 2006). "Radiation Poisoning Killed Ex-Russian Spy". The New York Times.
8. "Arafat's death: what is Polonium-210?". Al Jazeera. July 10, 2012.
9. J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
10. M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary.
11. G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
12. National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005. Check date values in: |access-date= (help)
13. N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. p. 11-50. ISBN 978-0-8493-0485-9.
14. "Universal Nuclide Chart". nucleonica. (registration required (help)).
15. Boutin, Chad. "Polonium's Most Stable Isotope Gets Revised Half-Life Measurement". nist.gov. NIST Tech Beat. Retrieved 9 September 2014.