Isotopes of samarium
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Naturally occurring samarium (Sm) is composed of 4 stable isotopes, 144Sm, 150Sm, 152Sm and 154Sm, and 3 extremely long-lived radioisotopes, 147Sm (1.06×1011y), 148Sm (7×1015y) and 149Sm (>2×1015y), with 152Sm being the most abundant (26.75% natural abundance).
151Sm has a half-life of 90 years, and 145Sm has a half-life of 340 days. All of the remaining radioisotopes have half-lives that are less than 2 days, and the majority of these have half-lives that are less than 48 seconds. This element also has 5 meta states with the most stable being 141mSm (t½ 22.6 minutes), 143m1Sm (t½ 66 seconds) and 139mSm (t½ 10.7 seconds).
The primary decay mode before the most abundant stable isotope, 152Sm, is electron capture, and the primary mode after is beta minus decay. The primary decay products before 152Sm are element Pm (promethium) isotopes, and the primary products after are element Eu (europium) isotopes.
Isotopes of samarium are used in samarium-neodymium dating for determining the age relationships of rocks and meteorites.
Standard atomic mass: 150.36(2) u
[edit] 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 | |||||||
| 128Sm | 62 | 66 | 127.95808(54)# | 0.5# s | 0+ | ||
| 129Sm | 62 | 67 | 128.95464(54)# | 550(100) ms | 5/2+# | ||
| 130Sm | 62 | 68 | 129.94892(43)# | 1# s | 0+ | ||
| 131Sm | 62 | 69 | 130.94611(32)# | 1.2(2) s | 5/2+# | ||
| 132Sm | 62 | 70 | 131.94069(32)# | 4.0(3) s | 0+ | ||
| 133Sm | 62 | 71 | 132.93867(21)# | 2.90(17) s | (5/2+) | ||
| 134Sm | 62 | 72 | 133.93397(21)# | 10(1) s | 0+ | ||
| 135Sm | 62 | 73 | 134.93252(17) | 10.3(5) s | (7/2+) | ||
| 135mSm | 0(300)# keV | 2.4(9) s | (3/2+,5/2+) | ||||
| 136Sm | 62 | 74 | 135.928276(13) | 47(2) s | 0+ | ||
| 136mSm | 2264.7(11) keV | 15(1) µs | (8-) | ||||
| 137Sm | 62 | 75 | 136.92697(5) | 45(1) s | (9/2-) | ||
| 137mSm | 180(50)# keV | 20# s | 1/2+# | ||||
| 138Sm | 62 | 76 | 137.923244(13) | 3.1(2) min | 0+ | ||
| 139Sm | 62 | 77 | 138.922297(12) | 2.57(10) min | 1/2+ | ||
| 139mSm | 457.40(22) keV | 10.7(6) s | 11/2- | ||||
| 140Sm | 62 | 78 | 139.918995(13) | 14.82(12) min | 0+ | ||
| 141Sm | 62 | 79 | 140.918476(9) | 10.2(2) min | 1/2+ | ||
| 141mSm | 176.0(3) keV | 22.6(2) min | 11/2- | ||||
| 142Sm | 62 | 80 | 141.915198(6) | 72.49(5) min | 0+ | ||
| 143Sm | 62 | 81 | 142.914628(4) | 8.75(8) min | 3/2+ | ||
| 143m1Sm | 753.99(16) keV | 66(2) s | 11/2- | ||||
| 143m2Sm | 2793.8(13) keV | 30(3) ms | 23/2(-) | ||||
| 144Sm | 62 | 82 | 143.911999(3) | STABLE | 0+ | 0.0307(7) | |
| 144mSm | 2323.60(8) keV | 880(25) ns | 6+ | ||||
| 145Sm | 62 | 83 | 144.913410(3) | 340(3) d | 7/2- | ||
| 145mSm | 8786.2(7) keV | 990(170) ns [0.96(+19-15) µs] | (49/2+) | ||||
| 146Sm | 62 | 84 | 145.913041(4) | 1.03(5)E+8 a | 0+ | ||
| 147Sm | 62 | 85 | 146.9148979(26) | 1.06(2)E+11 a | 7/2- | 0.1499(18) | |
| 148Sm | 62 | 86 | 147.9148227(26) | 7(3)E+15 a | 0+ | 0.1124(10) | |
| 149Sm | 62 | 87 | 148.9171847(26) | STABLE [>2E+15 a] | 7/2- | 0.1382(7) | |
| 150Sm | 62 | 88 | 149.9172755(26) | STABLE | 0+ | 0.0738(1) | |
| 151Sm | 62 | 89 | 150.9199324(26) | 90(8) a | 5/2- | ||
| 151mSm | 261.13(4) keV | 1.4(1) µs | (11/2)- | ||||
| 152Sm | 62 | 90 | 151.9197324(27) | STABLE | 0+ | 0.2675(16) | |
| 153Sm | 62 | 91 | 152.9220974(27) | 46.284(4) h | 3/2+ | ||
| 153mSm | 98.37(10) keV | 10.6(3) ms | 11/2- | ||||
| 154Sm | 62 | 92 | 153.9222093(27) | STABLE [>2.3E+18 a] | 0+ | 0.2275(29) | |
| 155Sm | 62 | 93 | 154.9246402(28) | 22.3(2) min | 3/2- | ||
| 156Sm | 62 | 94 | 155.925528(10) | 9.4(2) h | 0+ | ||
| 156mSm | 1397.55(9) keV | 185(7) ns | 5- | ||||
| 157Sm | 62 | 95 | 156.92836(5) | 8.03(7) min | (3/2-) | ||
| 158Sm | 62 | 96 | 157.92999(8) | 5.30(3) min | 0+ | ||
| 159Sm | 62 | 97 | 158.93321(11) | 11.37(15) s | 5/2- | ||
| 160Sm | 62 | 98 | 159.93514(21)# | 9.6(3) s | 0+ | ||
| 161Sm | 62 | 99 | 160.93883(32)# | 4.8(8) s | 7/2+# | ||
| 162Sm | 62 | 100 | 161.94122(54)# | 2.4(5) s | 0+ | ||
| 163Sm | 62 | 101 | 162.94536(75)# | 1# s | 1/2-# | ||
| 164Sm | 62 | 102 | 163.94828(86)# | 500# ms | 0+ | ||
| 165Sm | 62 | 103 | 164.95298(97)# | 200# ms | 5/2-# | ||
[edit] 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.
Note that all of the reported stablen isotopes 0f 62Sm are EE's, and that the isotope EO62Sm145 destabilizes in the direction of having 2 more neutrons and becoming EE60Nd144. The isotope EE62Sm146 is then reported to be an Alpha emitter and becoming EE60Nd142. The isotopes EO62Sm147 and EE62Sm148 are also reported as alpha emitters, and changing to EO6oNd143 and EE60Nd144which are both reported stable. The question is if the EE isotopes 62SM144,148,150,152,154 and the EO isotopes 62Sm147 and 149 are all stable or very long half lived and if EO62Sm145 changes in the direction of having 2 more neutrons then why would 2 more balanced neutrons added to a stable EE62Sm144 turn it into a short lived alpha emitter? Could they have been added on in the wrong (unbalanced} position? That is the trouble with alpha emitters. They obscure the underlying accumulation process.WFPMWFPM (talk) 04:37, 14 April 2008 (UTC)
[edit] References
- Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
- Isotopic compositions and standard atomic masses from Atomic weights of the elements. Review 2000 (IUPAC Technical Report). Pure Appl. Chem. Vol. 75, No. 6, pp. 683-800, (2003) and Atomic Weights Revised (2005).
- Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
- Audi, Bersillon, Blachot, Wapstra. The Nubase2003 evaluation of nuclear and decay properties, Nuc. Phys. A 729, pp. 3-128 (2003).
- National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the NuDat 2.1 database (retrieved Sept. 2005).
- David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.
| Isotopes of promethium | Isotopes of samarium | Isotopes of europium |
| Index to isotope pages · Table of nuclides | ||
