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Tin-121m

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Tin-121m

Tin (Sn) is the element with the greatest number of stable isotopes (ten) (three of them are potentially radioactive but have not been observed to decay), which is probably related to the fact that 50 is a "magic number" of protons. 29 additional unstable isotopes are known, including the "doubly magic" tin-100 (100Sn) (discovered in 1994)[1] and tin-132 (132Sn). The longest-lived radioisotope is 126Sn with a half-life of 230,000 years. All other radioisotopes have half-lives less than a year.

Tin-121m

Tin-121m is a radioisotope and nuclear isomer of tin with a halflife of 43.9 years.

In a normal thermal reactor, it has a very low fission product yield; thus, this isotope is not a significant contributor to nuclear waste. Fast fission or fission of some heavier actinides will produce 121mSn at higher yields. For example, its yield from U-235 is 0.0007% per thermal fission and 0.002% per fast fission.[2]

Tin-126

Yield, % per fission[3]
Thermal Fast 14 MeV
232Th not fissile 0.0481 ± 0.0077 0.87 ± 0.20
233U 0.224 ± 0.018 0.278 ± 0.022 1.92 ± 0.31
235U 0.056 ± 0.004 0.0137 ± 0.001 1.70 ± 0.14
238U not fissile 0.054 ± 0.004 1.31 ± 0.21
239Pu 0.199 ± 0.016 0.26 ± 0.02 2.02 ± 0.22
241Pu 0.082 ± 0.019 0.22 ± 0.03  ?

Tin-126 is a radioisotope of tin and one of only 7 long-lived fission products. While tin-126's halflife of 230,000 years translates to a low specific activity that limits its radioactive hazard, its short-lived decay product, antimony-126, emits high-energy gamma radiation, making external exposure to tin-126 a potential concern.

126Sn is in the middle of the mass range for fission products. Thermal reactors, which make up almost all current nuclear power plants, produce it at a very low yield (0.056% for 235U), since slow neutrons almost always fission 235U or 239Pu into unequal halves. Fast fission in a fast reactor or nuclear weapon, or fission of some heavy minor actinides like californium, will produce it at higher yields.

  • ANL factsheet


Table

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life decay
mode(s)[4][n 1]
daughter
isotope(s)[n 2]
nuclear
spin
representative
isotopic
composition
(mole fraction)
range of natural
variation
(mole fraction)
excitation energy
99Sn[n 3] 50 49 98.94933(64)# 5# ms 9/2+#
100Sn[n 4] 50 50 99.93904(76) 1.1(4) s
[0.94(+54-27) s]
β+ (83%) 100In 0+
β+, p (17%) 99Cd
101Sn 50 51 100.93606(32)# 3(1) s β+ 101In 5/2+#
β+, p (rare) 100Cd
102Sn 50 52 101.93030(14) 4.5(7) s β+ 102In 0+
β+, p (rare) 101Cd
102mSn 2017(2) keV 720(220) ns (6+)
103Sn 50 53 102.92810(32)# 7.0(6) s β+ 103In 5/2+#
β+, p (rare) 102Cd
104Sn 50 54 103.92314(11) 20.8(5) s β+ 104In 0+
105Sn 50 55 104.92135(9) 34(1) s β+ 105In (5/2+)
β+, p (rare) 104Cd
106Sn 50 56 105.91688(5) 115(5) s β+ 106In 0+
107Sn 50 57 106.91564(9) 2.90(5) min β+ 107In (5/2+)
108Sn 50 58 107.911925(21) 10.30(8) min β+ 108In 0+
109Sn 50 59 108.911283(11) 18.0(2) min β+ 109In 5/2(+)
110Sn 50 60 109.907843(15) 4.11(10) h EC 110In 0+
111Sn 50 61 110.907734(7) 35.3(6) min β+ 111In 7/2+
111mSn 254.72(8) keV 12.5(10) µs 1/2+
112Sn 50 62 111.904818(5) Observationally Stable[n 5] 0+ 0.0097(1)
113Sn 50 63 112.905171(4) 115.09(3) d β+ 113In 1/2+
113mSn 77.386(19) keV 21.4(4) min IT (91.1%) 113Sn 7/2+
β+ (8.9%) 113In
114Sn 50 64 113.902779(3) Stable[n 6] 0+ 0.0066(1)
114mSn 3087.37(7) keV 733(14) ns 7-
115Sn 50 65 114.903342(3) Stable[n 6] 1/2+ 0.0034(1)
115m1Sn 612.81(4) keV 3.26(8) µs 7/2+
115m2Sn 713.64(12) keV 159(1) µs 11/2-
116Sn 50 66 115.901741(3) Stable[n 6] 0+ 0.1454(9)
117Sn 50 67 116.902952(3) Stable[n 6] 1/2+ 0.0768(7)
117m1Sn 314.58(4) keV 13.76(4) d IT 117Sn 11/2-
117m2Sn 2406.4(4) keV 1.75(7) µs (19/2+)
118Sn 50 68 117.901603(3) Stable[n 6] 0+ 0.2422(9)
119Sn 50 69 118.903308(3) Stable[n 6] 1/2+ 0.0859(4)
119m1Sn 89.531(13) keV 293.1(7) d IT 119Sn 11/2-
119m2Sn 2127.0(10) keV 9.6(12) µs (19/2+)
120Sn 50 70 119.9021947(27) Stable[n 6] 0+ 0.3258(9)
120m1Sn 2481.63(6) keV 11.8(5) µs (7-)
120m2Sn 2902.22(22) keV 6.26(11) µs (10+)#
121Sn[n 7] 50 71 120.9042355(27) 27.03(4) h β- 121Sb 3/2+
121m1Sn 6.30(6) keV 43.9(5) a IT (77.6%) 121Sn 11/2-
β- (22.4%) 121Sb
121m2Sn 1998.8(9) keV 5.3(5) µs (19/2+)#
121m3Sn 2834.6(18) keV 0.167(25) µs (27/2-)
122Sn[n 7] 50 72 121.9034390(29) Observationally Stable[n 8] 0+ 0.0463(3)
123Sn[n 7] 50 73 122.9057208(29) 129.2(4) d β- 123Sb 11/2-
123m1Sn 24.6(4) keV 40.06(1) min β- 123Sb 3/2+
123m2Sn 1945.0(10) keV 7.4(26) µs (19/2+)
123m3Sn 2153.0(12) keV 6 µs (23/2+)
123m4Sn 2713.0(14) keV 34 µs (27/2-)
124Sn[n 7] 50 74 123.9052739(15) Observationally Stable[n 9] 0+ 0.0579(5)
124m1Sn 2204.622(23) keV 0.27(6) µs 5-
124m2Sn 2325.01(4) keV 3.1(5) µs 7-
124m3Sn 2656.6(5) keV 45(5) µs (10+)#
125Sn[n 7] 50 75 124.9077841(16) 9.64(3) d β- 125Sb 11/2-
125mSn 27.50(14) keV 9.52(5) min 3/2+
126Sn[n 10] 50 76 125.907653(11) 2.30(14)×105 a β- (66.5%) 126m2Sb 0+
β- (33.5%) 126m1Sb
126m1Sn 2218.99(8) keV 6.6(14) µs 7-
126m2Sn 2564.5(5) keV 7.7(5) µs (10+)#
127Sn 50 77 126.910360(26) 2.10(4) h β- 127Sb (11/2-)
127mSn 4.7(3) keV 4.13(3) min β- 127Sb (3/2+)
128Sn 50 78 127.910537(29) 59.07(14) min β- 128Sb 0+
128mSn 2091.50(11) keV 6.5(5) s IT 128Sn (7-)
129Sn 50 79 128.91348(3) 2.23(4) min β- 129Sb (3/2+)#
129mSn 35.2(3) keV 6.9(1) min β- (99.99%) 129Sb (11/2-)#
IT (.002%) 129Sn
130Sn 50 80 129.913967(11) 3.72(7) min β- 130Sb 0+
130m1Sn 1946.88(10) keV 1.7(1) min β- 130Sb (7-)#
130m2Sn 2434.79(12) keV 1.61(15) µs (10+)
131Sn 50 81 130.917000(23) 56.0(5) s β- 131Sb (3/2+)
131m1Sn 80(30)# keV 58.4(5) s β- (99.99%) 131Sb (11/2-)
IT (.0004%) 131Sn
131m2Sn 4846.7(9) keV 300(20) ns (19/2- to 23/2-)
132Sn 50 82 131.917816(15) 39.7(8) s β- 132Sb 0+
133Sn 50 83 132.92383(4) 1.45(3) s β- (99.97%) 133Sb (7/2-)#
β-, n (.0294%) 132Sb
134Sn 50 84 133.92829(11) 1.050(11) s β- (83%) 134Sb 0+
β-, n (17%) 133Sb
135Sn 50 85 134.93473(43)# 530(20) ms β- 135Sb (7/2-)
β-, n 134Sb
136Sn 50 86 135.93934(54)# 0.25(3) s β- 136Sb 0+
β-, n 135Sb
137Sn 50 87 136.94599(64)# 190(60) ms β- 137Sb 5/2-#

Notes

  • Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
  • 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.

References

  • Isotope masses from:
  • Isotopic compositions and standard atomic masses from:
  • Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.


Isotopes of indium Isotopes of tin Isotopes of antimony
Table of nuclides
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