Isotopes of tantalum

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Isotopes of tantalum (73Ta)
Main isotopes[1] Decay
abun­dance half-life (t1/2) mode pro­duct
177Ta synth 56.56 h
β+
177Hf
178Ta synth 2.36 h β+
178Hf
179Ta synth 1.82 y ε
179Hf
180Ta synth 8.125 h ε
180Hf
β−
180W
180mTa 0.0120%
stable
181Ta 99.988% stable
182Ta synth 114.43 d β−
182W
183Ta synth 5.1 d β−
183W
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    • Natural tantalum (73Ta) consists of two stable isotopes: 181Ta (99.988%) and 180m
    Ta
     (0.012%).

    There are also 35 known artificial

    observationally stable
    , meaning that they are predicted to be radioactive but no actual decay has been observed.

    Tantalum has been proposed as a "

    deny an area to either side as long as the dose is high enough, whereas radioactive contamination
    by alpha emitters which do not release significant amounts of gamma rays can be counteracted by ensuring the material is not incorporated.

    List of isotopes

    Nuclide
    [n 1]     		Z N Isotopic mass (Da)
    [n 2][n 3]     		Half-life
    [n 4]
    Decay
    mode
    [n 5]
    		 Daughter
    isotope
    [n 6][n 7]
    Spin and
    parity
    [n 8][n 4]
    		 Natural abundance (mole fraction)
    Excitation energy[n 4] Normal proportion Range of variation
    155
    Ta
         		73 82 154.97459(54)# 2.9+1.5
    −1.1     ms    [5]     		p 154Hf (11/2−)
    155m
    Ta
         		~323 keV 12+4
    −3     μs    [6]     		p 154Hf 11/2−?
    156
    Ta
    [7]     		73 83 155.97230(43)# 106(4) ms p (71%) 155Hf (2−)
    β+ (29%) 156Hf
    156m
    Ta
         		102(7) keV 0.36(4) s p 155Hf 9+
    157
    Ta
         		73 84 156.96819(22) 10.1(4) ms α (91%) 153Lu 1/2+
    β+ (9%) 157Hf
    157m1
    Ta
         		22(5) keV 4.3(1) ms 11/2−
    157m2
    Ta
         		1593(9) keV 1.7(1) ms α 153Lu (25/2−)
    158
    Ta
         		73 85 157.96670(22)# 49(8) ms α (96%) 154Lu (2−)
    β+ (4%) 158Hf
    158m
    Ta
         		141(9) keV 36.0(8) ms α (93%) 154Lu (9+)
    IT
    		 158Ta
    β+ 158Hf
    159
    Ta
         		73 86 158.963018(22) 1.04(9) s β+ (66%) 159Hf (1/2+)
    α (34%) 155Lu
    159m
    Ta
         		64(5) keV 514(9) ms α (56%) 155Lu (11/2−)
    β+ (44%) 159Hf
    160
    Ta
         		73 87 159.96149(10) 1.70(20) s α 156Lu (2#)−
    β+ 160Hf
    160m
    Ta
         		310(90)# keV 1.55(4) s β+ (66%) 160Hf (9)+
    α (34%) 156Lu
    161
    Ta
         		73 88 160.95842(6)# 3# s β+ (95%) 161Hf 1/2+#
    α (5%) 157Lu
    161m
    Ta
         		50(50)# keV 2.89(12) s 11/2−#
    162
    Ta
         		73 89 161.95729(6) 3.57(12) s β+ (99.92%) 162Hf 3+#
    α (.073%) 158Lu
    163
    Ta
         		73 90 162.95433(4) 10.6(18) s β+ (99.8%) 163Hf 1/2+#
    α (.2%) 159Lu
    164
    Ta
         		73 91 163.95353(3) 14.2(3) s β+ 164Hf (3+)
    165
    Ta
         		73 92 164.950773(19) 31.0(15) s β+ 165Hf 5/2−#
    165m
    Ta
         		60(30) keV 9/2−#
    166
    Ta
         		73 93 165.95051(3) 34.4(5) s β+ 166Hf (2)+
    167
    Ta
         		73 94 166.94809(3) 1.33(7) min β+ 167Hf (3/2+)
    168
    Ta
         		73 95 167.94805(3) 2.0(1) min β+ 168Hf (2−,3+)
    169
    Ta
         		73 96 168.94601(3) 4.9(4) min β+ 169Hf (5/2+)
    170
    Ta
         		73 97 169.94618(3) 6.76(6) min β+ 170Hf (3)(+#)
    171
    Ta
         		73 98 170.94448(3) 23.3(3) min β+ 171Hf (5/2−)
    172
    Ta
         		73 99 171.94490(3) 36.8(3) min β+ 172Hf (3+)
    173
    Ta
         		73 100 172.94375(3) 3.14(13) h β+ 173Hf 5/2−
    174
    Ta
         		73 101 173.94445(3) 1.14(8) h β+ 174Hf 3+
    175
    Ta
         		73 102 174.94374(3) 10.5(2) h β+ 175Hf 7/2+
    176
    Ta
         		73 103 175.94486(3) 8.09(5) h β+ 176Hf (1)−
    176m1
    Ta
         		103.0(10) keV 1.1(1) ms IT 176Ta (+)
    176m2
    Ta
         		1372.6(11)+X keV 3.8(4) µs (14−)
    176m3
    Ta
         		2820(50) keV 0.97(7) ms (20−)
    177
    Ta
         		73 104 176.944472(4) 56.56(6) h β+ 177Hf 7/2+
    177m1
    Ta
         		73.36(15) keV 410(7) ns 9/2−
    177m2
    Ta
         		186.15(6) keV 3.62(10) µs 5/2−
    177m3
    Ta
         		1355.01(19) keV 5.31(25) µs 21/2−
    177m4
    Ta
         		4656.3(5) keV 133(4) µs 49/2−
    178
    Ta
         		73 105 177.945778(16) 9.31(3) min β+ 178Hf 1+
    178m1
    Ta
         		100(50)# keV 2.36(8) h β+ 178Hf (7)−
    178m2
    Ta
         		1570(50)# keV 59(3) ms (15−)
    178m3
    Ta
         		3000(50)# keV 290(12) ms (21−)
    179
    Ta
         		73 106 178.9459295(23) 1.82(3) y EC 179Hf 7/2+
    179m1
    Ta
         		30.7(1) keV 1.42(8) µs (9/2)−
    179m2
    Ta
         		520.23(18) keV 335(45) ns (1/2)+
    179m3
    Ta
         		1252.61(23) keV 322(16) ns (21/2−)
    179m4
    Ta
         		1317.3(4) keV 9.0(2) ms IT 179Ta (25/2+)
    179m5
    Ta
         		1327.9(4) keV 1.6(4) µs (23/2−)
    179m6
    Ta
         		2639.3(5) keV 54.1(17) ms (37/2+)
    180
    Ta
         		73 107 179.9474648(24) 8.152(6) h EC (86%) 180Hf 1+
    β− (14%) 180W
    180m1
    Ta
         		77.1(8) keV Observationally stable[n 9][n 10] 9− 1.2(2)×10−4
    180m2
    Ta
         		1452.40(18) keV 31.2(14) µs 15−
    180m3
    Ta
         		3679.0(11) keV 2.0(5) µs (22−)
    180m4
    Ta
         		4171.0+X keV 17(5) µs (23, 24, 25)
    181
    Ta
         		73 108 180.9479958(20) Observationally stable[n 11] 7/2+ 0.99988(2)
    181m1
    Ta
         		6.238(20) keV 6.05(12) µs 9/2−
    181m2
    Ta
         		615.21(3) keV 18(1) µs 1/2+
    181m3
    Ta
         		1485(3) keV 25(2) µs 21/2−
    181m4
    Ta
         		2230(3) keV 210(20) µs 29/2−
    182
    Ta
         		73 109 181.9501518(19) 114.43(3) d β− 182W 3−
    182m1
    Ta
         		16.263(3) keV 283(3) ms IT 182Ta 5+
    182m2
    Ta
         		519.572(18) keV 15.84(10) min 10−
    183
    Ta
         		73 110 182.9513726(19) 5.1(1) d β− 183W 7/2+
    183m
    Ta
         		73.174(12) keV 107(11) ns 9/2−
    184
    Ta
         		73 111 183.954008(28) 8.7(1) h β− 184W (5−)
    185
    Ta
         		73 112 184.955559(15) 49.4(15) min β− 185W (7/2+)#
    185m
    Ta
         		1308(29) keV >1 ms (21/2−)
    186
    Ta
         		73 113 185.95855(6) 10.5(3) min β− 186W (2−,3−)
    186m
    Ta
         		1.54(5) min
    187
    Ta
         		73 114 186.96053(21)# 2# min
    [>300 ns]     		β− 187W 7/2+#
    188
    Ta
         		73 115 187.96370(21)# 20# s
    [>300 ns]     		β− 188W
    189
    Ta
         		73 116 188.96583(32)# 3# s
    [>300 ns]     		7/2+#
    190
    Ta
         		73 117 189.96923(43)# 0.3# s
    This table header & footer:
    1. ^ mTa – 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. ^ a b c # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
    5. ^ Modes of decay:
      EC: Electron capture
      IT:
      Isomeric transition


      p: Proton emission
    6. ^ Bold italics symbol as daughter – Daughter product is nearly stable.
    7. ^ Bold symbol as daughter – Daughter product is stable.
    8. ^ ( ) spin value – Indicates spin with weak assignment arguments.
    9. ^ Only known observationally stable nuclear isomer, believed to decay by isomeric transition to 180Ta, β− decay to 180W, or electron capture to 180Hf with a half-life over 2.9×1017 years;[8] also theorized to undergo α decay to 176Lu
    10. ^ One of the few (observationally) stable odd-odd nuclei
    11. ^ Believed to undergo α decay to 177Lu

    Tantalum-180m

    The nuclide 180m
    Ta
     (m denotes a

    isomeric transition to the ground state of 180
    Ta
    , beta decay to 180
    W
    , and electron capture to 180
    Hf
    . However, no radioactivity from any decay mode of this nuclear isomer has ever been observed. As of 2023, the half-life of 180mTa is calculated from experimental observation to be at least 2.9×1017 (290 quadrillion) years.[8][9][10] The very slow decay of 180m
    Ta
     is attributed to its high spin (9 units) and the low spin of lower-lying states. Gamma or beta decay would require many units of angular momentum to be removed in a single step, so that the process would be very slow.[11]

    The very unusual nature of 180mTa is that the ground state of this isotope is less stable than the isomer. This phenomenon is exhibited in

    eV (i.e. a temperature of 300 million kelvin), the nuclear isomers are expected to be fully thermalized, meaning that 180Ta rapidly transitions between spin states and its overall half-life is predicted to be 11 hours.[12]

    It is one of only five stable nuclides to have both an odd number of protons and an odd number of neutrons, the other four stable odd-odd nuclides being 2H, 6Li, 10B and 14N.[13]

    References

    1. doi:10.1088/1674-1137/abddae
      .
    2. ^ "Standard Atomic Weights: Tantalum". CIAAW. 2005.
    3. ISSN 1365-3075
      .
    4. ^ D. T. Win; M. Al Masum (2003). "Weapons of Mass Destruction" (PDF). Assumption University Journal of Technology. 6 (4): 199–219.
    5. ISSN 0556-2813
      .
    6. ISSN 0556-2813
      . Retrieved 12 June 2023.
    7. ISSN 0556-2813
      . Retrieved 21 June 2023.
    8. ^
      doi:10.1103/PhysRevLett.131.152501
      .
    9. ^ Conover, Emily (2016-10-03). "Rarest nucleus reluctant to decay". Retrieved 2016-10-05.
    10. S2CID 118497863
      .
    11. ^ Quantum mechanics for engineers Leon van Dommelen, Florida State University
    12. S2CID 44724195.{{cite journal}}: CS1 maint: multiple names: authors list (link
      )
    13. OCLC 179976746. Archived from the original
      on 24 July 2017. Retrieved 2008-05-23.
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