Isotopes of lanthanum

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Isotopes of lanthanum (57La)
Main isotopes[1] Decay
abun­dance half-life (t1/2) mode pro­duct
137La synth 6×104 y ε
137Ba
138La 0.089% 1.05×1011 y ε
138Ba
β−
138Ce
139La 99.911%
stable
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  • edit
    • Stable Z/N chart of La and Ba

    Naturally occurring

    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. Lighter isotopes mostly decay to isotopes of barium and heavy ones mostly decay to isotopes of cerium
    . 138La can decay to both.

    The isotopes of lanthanum range in

    u
    (116La) to 154.96 u (155La).

    List of isotopes


    Nuclide
    [n 1]     		Z N Isotopic mass (Da)
    [n 2][n 3]     		Half-life
    [n 4][n 5]
    Decay
    mode
    [n 6]
    		 Daughter
    isotope
    [n 7][n 8]
    Spin and
    parity
    [n 9][n 5]
    		 Natural abundance (mole fraction) Note
    Excitation energy[n 5] Normal proportion Range of variation
    116La[4] 57 59 50(22) ms p (~60%) 115Ba
    β+ (~40%) 116Ba
    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+ extinct
    138La[n 10] 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[n 11] 57 82 138.9063533(26) Stable 7/2+ 0.99910(1)
    140La[n 11] 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+#
    This table header & footer:
    1. ^ mLa – Excited nuclear isomer.
    2. ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
    3. ^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
    4. age of universe
      .
    5. ^ a b c # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
    6. ^ Modes of decay:
      EC: Electron capture
      IT:
      Isomeric transition
      n: Neutron emission
      p: Proton emission
    7. ^ Bold italics symbol as daughter – Daughter product is nearly stable.
    8. ^ Bold symbol as daughter – Daughter product is stable.
    9. ^ ( ) spin value – Indicates spin with weak assignment arguments.
    10. ^ Primordial radionuclide
    11. ^
      Fission product

    References

    1. doi:10.1088/1674-1137/abddae
      .
    2. ^ "Standard Atomic Weights: Lanthanum". CIAAW. 2005.
    3. ISSN 1365-3075
      .
    4. S2CID 253512231
      .
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