Isotopes of silicon

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Isotopes of silicon (14Si)
Main isotopes[1] Decay
abun­dance half-life (t1/2) mode pro­duct
28Si 92.2%
stable
29Si 4.7% stable
30Si 3.1% stable
31Si trace 2.62 h
β−
31P
32Si trace 153 y β− 32P
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    • Silicon (14Si) has 23 known isotopes, with mass numbers ranging from 22 to 44. 28Si (the most abundant isotope, at 92.23%), 29Si (4.67%), and 30Si (3.1%) are stable. The longest-lived radioisotope is 32Si, which is produced by cosmic ray spallation of argon. Its half-life has been determined to be approximately 150 years (with decay energy 0.21 MeV), and it decays by beta emission to 32P (which has a 14.27-day half-life)[1] and then to 32S. After 32Si, 31Si has the second longest half-life at 157.3 minutes. All others have half-lives under 7 seconds.

    A chart showing the relative abundances of the naturally occurring isotopes of silicon.

    List of isotopes

    Nuclide
    [n 1]     		Z N Isotopic mass (Da)[4]
    [n 2][n 3]     		Half-life[1]
    [n 4]
    Decay
    mode[1]
    [n 5]
    		 Daughter
    isotope
    [n 6]
    Spin and
    parity[1]
    [n 7][n 4]
    		 Natural abundance (mole fraction)
    Excitation energy Normal proportion[1] Range of variation
    22Si 14 8 22.03611(54)# 28.7(11) ms β+, p (62%) 21Mg 0+
    β+ (37%) 22Al
    β+, 2p (0.7%) 20Na
    23Si 14 9 23.02571(54)# 42.3(4) ms β+, p (88%) 22Mg 3/2+#
    β+ (8%) 23Al
    β+, 2p (3.6%) 21Na
    24Si 14 10 24.011535(21) 143.2 (21) ms β+ (65.5%) 24Al 0+
    β+, p (34.5%) 23Mg
    25Si 14 11 25.004109(11) 220.6(10) ms β+ (65%) 25Al 5/2+
    β+, p (35%) 24Mg
    26Si 14 12 25.99233382(12) 2.2453(7) s β+ 26Al 0+
    27Si 14 13 26.98670469(12) 4.117(14) s β+ 27Al 5/2+
    28Si 14 14 27.97692653442(55) Stable 0+ 0.92223(19) 0.92205–0.92241
    29Si 14 15 28.97649466434(60) Stable 1/2+ 0.04685(8) 0.04678–0.04692
    30Si 14 16 29.973770137(23) Stable 0+ 0.03092(11) 0.03082–0.03102
    31Si 14 17 30.975363196(46) 157.16(20) min β− 31P 3/2+
    32Si 14 18 31.97415154(32) 157(7) y β− 32P 0+ trace
    cosmogenic
    33Si 14 19 32.97797696(75) 6.18(18) s β− 33P 3/2+
    34Si 14 20 33.97853805(86) 2.77(20) s β− 34P 0+
    34mSi 4256.1(4) keV <210 ns IT 34Si (3−)
    35Si 14 21 34.984550(38) 780(120) ms β− 35P 7/2−#
    β−, n? 34P
    36Si 14 22 35.986649(77) 503(2) ms β− (88%) 36P 0+
    β−, n (12%) 35P
    37Si 14 23 36.99295(12) 141.0(35) ms β− (83%) 37P (5/2−)
    β−, n (17%) 36P
    β−, 2n? 35P
    38Si 14 24 37.99552(11) 63(8) ms β− (75%) 38P 0+
    β−, n (25%) 37P
    39Si 14 25 39.00249(15) 41.2(41) ms β− (67%) 39P (5/2−)
    β−, n (33%) 38P
    β−, 2n? 37P
    40Si 14 26 40.00608(13) 31.2(26) ms β− (62%) 40P 0+
    β−, n (38%) 39P
    β−, 2n? 38P
    41Si 14 27 41.01417(32)# 20.0(25) ms β−, n (>55%) 40P 7/2−#
    β− (<45%) 41P
    β−, 2n? 39P
    42Si 14 28 42.01808(32)# 15.5(4 (
    sys)) ms[5]
    		 β− (51%) 42P 0+
    β−, n (48%) 41P
    β−, 2n (1%) 40P
    43Si 14 29 43.02612(43)# 13(4 (
    sys)) ms[5]
    		 β−, n (52%) 42P 3/2−#
    β− (27%) 43P
    β−, 2n (21%) 41P
    44Si 14 30 44.03147(54)# 4# ms [>360 ns] β−? 44P 0+
    β−, n? 43P
    β−, 2n? 42P
    This table header & footer:
    1. ^ mSi – 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 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
    5. ^ Modes of decay:
      IT:
      Isomeric transition
      n: Neutron emission
      p: Proton emission
    6. ^ Bold symbol as daughter – Daughter product is stable.
    7. ^ ( ) spin value – Indicates spin with weak assignment arguments.

    Silicon-28

    Silicon-28, the most abundant isotope of silicon, is of particular interest in the construction of

    Avogadro project sought to develop a new definition of the kilogram by making a 93.75 mm (3.691 in) sphere of the isotope and determing the exact number of atoms in the sample.[8][9]

    Silicon-28 is produced in stars during the alpha process and the oxygen-burning process, and drives the silicon-burning process in massive stars shortly before they go supernova.[10][11]

    Silicon-29

    Silicon-29 is of note as the only stable silicon isotope with a

    hyperfine transition studies, for example to study the properties of the so-called A-center defect in pure silicon.[13]

    Silicon-34

    Silicon-34 is a radioactive isotope wth a half-life of 2.8 seconds.

    242Cm with a branching ratio of approximately 1×10−16.[17]

    References

    1. ^
      doi:10.1088/1674-1137/abddae
      .
    2. ^ "Standard Atomic Weights: Silicon". CIAAW. 2009.
    3. ISSN 1365-3075
      .
    4. doi:10.1088/1674-1137/abddaf
      .
    5. ^
      S2CID 253600995
      .
    6. ^ "Beyond Six Nines: Ultra-enriched Silicon Paves the Road to Quantum Computing". NIST. 2014-08-11.
    7. ISSN 0022-3727
      .
    8. ^ Powell, Devin (1 July 2008). "Roundest Objects in the World Created". New Scientist. Retrieved 16 June 2015.
    9. ^ Keats, Jonathon. "The Search for a More Perfect Kilogram". Wired. Retrieved 16 December 2023.
    10. S2CID 118974639
      .
    11. ISBN 978-9810220334
      .
    12. ISBN 978-0-08-037941-8
      .
    13. ISSN 0031-899X
      .
    14. doi:10.1103/PhysRevC.100.034306
      .
    15. ^ "Physicists find atomic nucleus with a 'bubble' in the middle". 24 October 2016. Retrieved 26 December 2023.
    16. doi:10.1038/nphys3916
      .
    17. ^ Bonetti, R.; Guglielmetti, A. (2007). "Cluster radioactivity: an overview after twenty years" (PDF). Romanian Reports in Physics. 59: 301–310. Archived from the original (PDF) on 19 September 2016.

    External links

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