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- List of isotopes Notes
- References
{{infobox lanthanum isotopes}}Naturally occurring lanthanum (57La) is composed of one stable (139La) and one radioactive (138La) isotope, with the stable isotope, 139La, being the most abundant (99.91% natural abundance). There are 38 radioisotopes that have been characterized, with the most stable being 138La, with a half-life of 1.02×1011 years; 137La, with a half-life of 60,000 years and 140La, with a half-life of 1.6781 days. The remaining radioactive isotopes have half-lives that are less than a day and the majority of these have half-lives that are less than 1 minute. This element also has 12 nuclear isomers, the longest-lived of which is 132mLa, with a half-life of 24.3 minutes. The isotopes of lanthanum range in atomic weight from 116.95 u (117La) to 154.96 u (155La). List of isotopes nuclide symbol | Z(p) | N(n) | isotopic mass (u) | half-life[1] | decay mode(s)[2][3] | daughter isotope(s)[4] | nuclear spin and parity | representative isotopic composition (mole fraction) | range of natural variation (mole fraction) | excitation energy |
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117La | 57 | 60 | 116.95007(43)# | 23.5(26) ms | β+ | 117Ba | (3/2+,3/2−) | | | p | 116Ba | 117mLa | 151(12) keV | 10(5) ms | (9/2+) | 118La | 57 | 61 | 117.94673(32)# | 200# ms | β+ | 118Ba | 119La | 57 | 62 | 118.94099(43)# | 1# s | β+ | 119Ba | 11/2−# | 120La | 57 | 63 | 119.93807(54)# | 2.8(2) s | β+ | 120Ba | | | | β+, p | 119Cs | 121La | 57 | 64 | 120.93301(54)# | 5.3(2) s | β+ | 121Ba | 11/2−# | | | β+, p | 120Cs | 122La | 57 | 65 | 121.93071(32)# | 8.6(5) s | β+ | 122Ba | | | | β+, p | 121Cs | 123La | 57 | 66 | 122.92624(21)# | 17(3) s | β+ | 123Ba | 11/2−# | 124La | 57 | 67 | 123.92457(6) | 29.21(17) s | β+ | 124Ba | (7−,8−) | 124mLa | 100(100)# keV | 21(4) s | low(+#) | 125La | 57 | 68 | 124.920816(28) | 64.8(12) s | β+ | 125Ba | (11/2−) | 125mLa | 107.0(10) keV | 390(40) ms | (3/2+) | 126La | 57 | 69 | 125.91951(10) | 54(2) s | β+ | 126Ba | (5)(+#) | 126mLa | 210(410) keV | 20(20) s | (0−,1−,2−) | 127La | 57 | 70 | 126.916375(28) | 5.1(1) min | β+ | 127Ba | (11/2−) | 127mLa | 14.8(12) keV | 3.7(4) min | β+ | 127Ba | (3/2+) | | | IT | 127La | 128La | 57 | 71 | 127.91559(6) | 5.18(14) min | β+ | 128Ba | (5+) | 128mLa | 100(100)# keV | <1.4 min | IT | 128La | (1+,2−) | 129La | 57 | 72 | 128.912693(22) | 11.6(2) min | β+ | 129Ba | 3/2+ | 129mLa | 172.1(4) keV | 560(50) ms | IT | 129La | 11/2− | 130La | 57 | 73 | 129.912369(28) | 8.7(1) min | β+ | 130Ba | 3(+) | 131La | 57 | 74 | 130.91007(3) | 59(2) min | β+ | 131Ba | 3/2+ | 131mLa | 304.52(24) keV | 170(10) µs | 11/2− | 132La | 57 | 75 | 131.91010(4) | 4.8(2) h | β+ | 132Ba | 2− | 132mLa | 188.18(11) keV | 24.3(5) min | IT (76%) | 132La | 6− | | | β+ (24%) | 132Ba | 133La | 57 | 76 | 132.90822(3) | 3.912(8) h | β+ | 133Ba | 5/2+ | 134La | 57 | 77 | 133.908514(21) | 6.45(16) min | β+ | 134Ba | 1+ | 135La | 57 | 78 | 134.906977(11) | 19.5(2) h | β+ | 135Ba | 5/2+ | 136La | 57 | 79 | 135.90764(6) | 9.87(3) min | β+ | 136Ba | 1+ | 136mLa | 255(9) keV | 114(3) ms | IT | 136La | (8)(−#) | 137La | 57 | 80 | 136.906494(14) | 6(2)×104 y | EC | 137Ba | 7/2+ | 138La[5] | 57 | 81 | 137.907112(4) | 1.02(1)×1011 y | β+ (66.4%) | 138Ba | 5+ | 9.0(1)×10−4 | | β− (33.6%) | 138Ce | 138mLa | 72.57(3) keV | 116(5) ns | (3)+ | 139La[6] | 57 | 82 | 138.9063533(26) | Stable | 7/2+ | 0.99910(1) | 140La[6] | 57 | 83 | 139.9094776(26) | 1.6781(3) d | β− | 140Ce | 3− | 141La | 57 | 84 | 140.910962(5) | 3.92(3) h | β− | 141Ce | (7/2+) | 142La | 57 | 85 | 141.914079(6) | 91.1(5) min | β− | 142Ce | 2− | 143La | 57 | 86 | 142.916063(17) | 14.2(1) min | β− | 143Ce | (7/2)+ | 144La | 57 | 87 | 143.91960(5) | 40.8(4) s | β− | 144Ce | (3−) | 145La | 57 | 88 | 144.92165(10) | 24.8(20) s | β− | 145Ce | (5/2+) | 146La | 57 | 89 | 145.92579(8) | 6.27(10) s | β− (99.99%) | 146Ce | 2− | | | β−, n (.007%) | 145Ce | 146mLa | 130(130) keV | 10.0(1) s | β− | 146Ce | (6−) | 147La | 57 | 90 | 146.92824(5) | 4.015(8) s | β− (99.96%) | 147Ce | (5/2+) | | | β−, n (.04%) | 146Ce | 148La | 57 | 91 | 147.93223(6) | 1.26(8) s | β− (99.85%) | 148Ce | (2−) | | | β−, n (.15%) | 147Ce | 149La | 57 | 92 | 148.93473(34)# | 1.05(3) s | β− (98.6%) | 149Ce | 5/2+# | | | β−, n (1.4%) | 148Ce | 150La | 57 | 93 | 149.93877(43)# | 510(30) ms | β− (97.3%) | 150Ce | (3+) | | | β−, n (2.7%) | 149Ce | 151La | 57 | 94 | 150.94172(43)# | 300# ms [>300 ns] | β− | 151Ce | 5/2+# | 152La | 57 | 95 | 151.94625(43)# | 200# ms [>300 ns] | β− | 152Ce | 153La | 57 | 96 | 152.94962(64)# | 150# ms [>300 ns] | β− | 153Ce | 5/2+# | 154La | 57 | 97 | 153.95450(64)# | 100# ms | β− | 154Ce | 155La | 57 | 98 | 154.95835(86)# | 60# ms | β− | 155Ce | 5/2+# |
1. ^Bold for isotopes with half-lives longer than the age of the universe (nearly stable) 2. ^{{cite web |url=http://www.nucleonica.net/unc.aspx |title=Universal Nuclide Chart |publisher=nucleonica |registration=yes}} 3. ^Abbreviations: EC: Electron capture IT: Isomeric transition 4. ^Bold for stable isotopes, bold italics for near-stable isotopes (half-life longer than the age of the universe) 5. ^Primordial radionuclide 6. ^1 Fission product
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:
- {{CAWIA 2003}}
- {{CIAAW 2005}}
- Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
- {{NUBASE 2003}}
- {{NNDC}}
- {{CRC85|chapter=11}}
{{Navbox element isotopes}} 3 : Lanthanum|Isotopes of lanthanum|Lists of isotopes by element |