釤（原子量：15036 2）在自然界中存在 5 種穩定同位素（144Sm、149Sm、150Sm、152Sm、154Sm）和 2 種長壽命放射性同位素（半衰期 106 年的 147Sm 和半衰期 7 年的 148Sm），其中 152Sm 的丰度最高，達 2674。146Sm 的半衰期也很長，但不足以在今天大量存在，現為。它可用於太陽系的測年。2012 年一篇把 146Sm 的半衰期從 103 5 年更新到 68 7 年的論文已於 2023 年撤稿。它是不確定是不是的核素中半衰期最長的。 除了以上 8 種同位素以外，釤最長壽的放射性同位素是半衰期 946 年的 151Sm 以及半衰期 340 天的 145Sm。剩下的同位素原子量介於 129 至 168，半衰期都短於兩天。 圖表 129Sm styletextalignright 62 styletextalignright 67 12895464 54 550 100 ms 52 130Sm styletextalignright 62 styletextalignright 68 12994892 43 1 s 130Pm 0 rowspan2131Sm rowspan2 styletextalignright 62 rowspan2 styletextalignright 69 rowspan213094611 32 rowspan212 2 s 131Pm rowspan252 rowspan2 rowspan2 （不常見） 130Nd rowspan2132Sm rowspan2 styletextalignright 62 rowspan2 styletextalignright 70 rowspan213194069 32 rowspan240 3 s 132Pm rowspan20 rowspan2 rowspan2 131Nd rowspan2133Sm rowspan2 styletextalignright 62 rowspan2 styletextalignright 71 rowspan213293867 21 rowspan2290 17 s 133Pm rowspan252 rowspan2 rowspan2 132Nd 134Sm styletextalignright 62 styletextalignright 72 13393397 21 10 1 s 134Pm 0 rowspan2135Sm rowspan2 styletextalignright 62 rowspan2 styletextalignright 73 rowspan213493252 17 rowspan2103 5 s 9998 135Pm rowspan272 rowspan2 rowspan2 02 134Nd styletextindent1em 135mSm colspan3 styletextindent2em 0 300 keV 24 9 s 135Pm 3252 136Sm styletextalignright 62 styletextalignright 74 135928276 13 47 2 s 136Pm 0 styletextindent1em 136mSm colspan3 styletextindent2em 22647 11 keV 15 1 µs 8 137Sm styletextalignright 62 styletextalignright 75 13692697 5 45 1 s 137Pm 92 styletextindent1em 137mSm colspan3 styletextindent2em 180 50 keV 20 s 137Pm 12 138Sm styletextalignright 62 styletextalignright 76 137923244 13 31 2 min 138Pm 0 139Sm styletextalignright 62 styletextalignright 77 138922297 12 257 10 min 139Pm 12 rowspan2 styletextindent1em 139mSm rowspan2 colspan3 styletextindent2em 45740 22 keV rowspan2107 6 s IT 937 139Sm rowspan2112 rowspan2 rowspan2 63 139Pm 140Sm styletextalignright 62 styletextalignright 78 139918995 13 1482 12 min 140Pm 0 141Sm styletextalignright 62 styletextalignright 79 140918476 9 102 2 min 141Pm 12 rowspan2 styletextindent1em 141mSm rowspan2 colspan3 styletextindent2em 1760 3 keV rowspan2226 2 min 9969 141Pm rowspan2112 rowspan2 rowspan2 IT 31 141Sm 142Sm styletextalignright 62 styletextalignright 80 141915198 6 7249 5 min 142Pm 0 143Sm styletextalignright 62 styletextalignright 81 142914628 4 875 8 min 143Pm 32 rowspan2 styletextindent1em 143m1Sm rowspan2 colspan3 styletextindent2em 75399 16 keV rowspan266 2 s IT 9976 143Sm rowspan2112 rowspan2 rowspan2 24 143Pm styletextindent1em 143m2Sm colspan3 styletextindent2em 27938 13 keV 30 3 ms 232 144Sm styletextalignright 62 styletextalignright 82 143911999 3 colspan3 aligncenter 觀測上穩定 Believed to undergo decay to 144Nd 0 00307 7 styletextindent1em 144mSm colspan3 styletextindent2em 232360 8 keV 880 25 ns 6 145Sm styletextalignright 62 styletextalignright 83 144913410 3 340 3 d 145Pm 72 styletextindent1em 145mSm colspan3 styletextindent2em 87862 7 keV 990 170 ns 096 1915 µs 492 146SmPrimordial radioisotope styletextalignright 62 styletextalignright 84 145913041 4 920 26 a 142Nd 0 痕量 147SmFission productUsed in Samariumneodymium dating styletextalignright 62 styletextalignright 85 1469148979 26 106 21011 a 143Nd 72 01499 18 148Sm styletextalignright 62 styletextalignright 86 1479148227 26 7 31015 a 144Nd 0 01124 10 149SmNeutron poison in reactors styletextalignright 62 styletextalignright 87 1489171847 26 colspan3 aligncenter 觀測上穩定 Believed to undergo decay to 145Nd with a halflife over 21015 years 72 01382 7 150Sm styletextalignright 62 styletextalignright 88 1499172755 26 colspan3 aligncenter 觀測上穩定 Believed to undergo decay to 146Nd 0 00738 1 151Sm styletextalignright 62 styletextalignright 89 1509199324 26 888 24 a 151Eu 52 styletextindent1em 151mSm colspan3 styletextindent2em 26113 4 keV 14 1 µs 112 152Sm styletextalignright 62 styletextalignright 90 1519197324 27 colspan3 aligncenter 觀測上穩定 Believed to undergo decay to 148Nd 0 02675 16 153Sm styletextalignright 62 styletextalignright 91 1529220974 27 46284 4 h 153Eu 32 styletextindent1em 153mSm colspan3 styletextindent2em 9837 10 keV 106 3 ms IT 153Sm 112 154Sm styletextalignright 62 styletextalignright 92 1539222093 27 colspan3 aligncenter 觀測上穩定 Believed to undergo decay to 154Gd with a halflife over 231018 years 0 02275 29 155Sm styletextalignright 62 styletextalignright 93 1549246402 28 223 2 min 155Eu 32 156Sm styletextalignright 62 styletextalignright 94 155925528 10 94 2 h 156Eu 0 styletextindent1em 156mSm colspan3 styletextindent2em 139755 9 keV 185 7 ns 5 157Sm styletextalignright 62 styletextalignright 95 15692836 5 803 7 min 157Eu 32 158Sm styletextalignright 62 styletextalignright 96 15792999 8 530 3 min 158Eu 0 159Sm styletextalignright 62 styletextalignright 97 15893321 11 1137 15 s 159Eu 52 160Sm styletextalignright 62 styletextalignright 98 15993514 21 96 3 s 160Eu 0 161Sm styletextalignright 62 styletextalignright 99 16093883 32 48 8 s 161Eu 72 162Sm styletextalignright 62 styletextalignright 100 16194122 54 24 5 s 162Eu 0 163Sm styletextalignright 62 styletextalignright 101 16294536 75 1 s 163Eu 12 164Sm styletextalignright 62 styletextalignright 102 16394828 86 500 ms 164Eu 0 165Sm styletextalignright 62 styletextalignright 103 16495298 97 200 ms 165Eu 52 參考文獻 Isotope masses from Ame2003 Atomic Mass Evaluation by G Audi AH 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 683800 2003 and Atomic Weights Revised 2005 Halflife spin and isomer data selected from these sources Editing notes on this articles talk page Audi Bersillon Blachot Wapstra The Nubase2003 evaluation of nuclear and decay properties Nuc Phys A 729 pp 3128 2003 National Nuclear Data Center Brookhaven National Laboratory Information extracted from the NuDat 21 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 Sm Category 釤