Isotopes of strontium

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Isotopes of strontium (38Sr)
Main isotopes[1] Decay
abun­dance half-life (t1/2) mode pro­duct
82Sr synth 25.36 d ε 82Rb
83Sr synth 1.35 d ε
83Rb
β+
 		83Rb
γ
 		–
84Sr 0.56%
stable
85Sr synth 64.84 d ε
85Rb
γ –
86Sr 9.86% stable
87Sr 7% stable
88Sr 82.6% stable
89Sr synth 50.52 d
β−
89Y
90Sr trace 28.90 y β− 90Y
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    • The alkaline earth metal strontium (38Sr) has four stable, naturally occurring isotopes: 84Sr (0.56%), 86Sr (9.86%), 87Sr (7.0%) and 88Sr (82.58%). Its standard atomic weight is 87.62(1).

    Only 87Sr is

    radioactive alkali metal 87Rb, which has a half-life of 4.88 × 1010 years (i.e. more than three times longer than the current age of the universe). Thus, there are two sources of 87Sr in any material: primordial, formed during nucleosynthesis along with 84Sr, 86Sr and 88Sr; and that formed by radioactive decay of 87Rb. The ratio 87Sr/86Sr is the parameter typically reported in geologic investigations;[4] ratios in minerals and rocks have values ranging from about 0.7 to greater than 4.0 (see rubidium–strontium dating). Because strontium has an electron configuration similar to that of calcium, it readily substitutes for calcium in minerals
    .

    In addition to the four stable isotopes, thirty-two unstable isotopes of strontium are known to exist, ranging from 73Sr to 108Sr. Radioactive isotopes of strontium primarily decay into the neighbouring elements

    beta minus decay) and rubidium (85Sr, 83Sr and lighter isotopes, via positron emission or electron capture). The longest-lived of these isotopes, and the most relevantly studied, are 90Sr with a half-life of 28.9 years, 85Sr with a half-life of 64.853 days, and 89Sr (89Sr) with a half-life
    of 50.57 days. All other strontium isotopes have half-lives shorter than 50 days, most under 100 minutes.

    beta particles
    directly to the cancerous portions of the bone, where calcium turnover is greatest. Strontium-90 is a by-product of
    beta emitter, it is used in SNAP (Systems for Nuclear Auxiliary Power) devices. These devices hold promise for use in spacecraft
    , remote weather stations, navigational buoys, etc., where a lightweight, long-lived, nuclear-electric power source is required.

    In 2020, researchers have found that mirror nuclides 73Sr and 73Br were found to not behave identically to each other as expected.[7]

    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 Normal proportion Range of variation
    73Sr 38 35 72.96597(64)# >25 ms β+ (>99.9%) 73Rb 1/2−#
    β+, p (<.1%) 72Kr
    74Sr 38 36 73.95631(54)# 50# ms [>1.5 µs] β+ 74Rb 0+
    75Sr 38 37 74.94995(24) 88(3) ms β+ (93.5%) 75Rb (3/2−)
    β+, p (6.5%) 74Kr
    76Sr 38 38 75.94177(4) 7.89(7) s β+ 76Rb 0+
    77Sr 38 39 76.937945(10) 9.0(2) s β+ (99.75%) 77Rb 5/2+
    β+, p (.25%) 76Kr
    78Sr 38 40 77.932180(8) 159(8) s β+ 78Rb 0+
    79Sr 38 41 78.929708(9) 2.25(10) min β+ 79Rb 3/2(−)
    80Sr 38 42 79.924521(7) 106.3(15) min β+ 80Rb 0+
    81Sr 38 43 80.923212(7) 22.3(4) min β+ 81Rb 1/2−
    82Sr 38 44 81.918402(6) 25.36(3) d EC 82Rb 0+
    83Sr 38 45 82.917557(11) 32.41(3) h β+ 83Rb 7/2+
    83mSr 259.15(9) keV 4.95(12) s IT 83Sr 1/2−
    84Sr 38 46 83.913425(3)
    Observationally Stable[n 9]
    		 0+ 0.0056 0.0055–0.0058
    85Sr 38 47 84.912933(3) 64.853(8) d EC 85Rb 9/2+
    85mSr 238.66(6) keV 67.63(4) min IT (86.6%) 85Sr 1/2−
    β+ (13.4%) 85Rb
    86Sr 38 48 85.9092607309(91) Stable 0+ 0.0986 0.0975–0.0999
    86mSr 2955.68(21) keV 455(7) ns 8+
    87Sr[n 10] 38 49 86.9088774970(91) Stable 9/2+ 0.0700 0.0694–0.0714
    87mSr 388.533(3) keV 2.815(12) h IT (99.7%) 87Sr 1/2−
    EC (.3%) 87Rb
    88Sr[n 11] 38 50 87.9056122571(97) Stable 0+ 0.8258 0.8229–0.8275
    89Sr[n 11] 38 51 88.9074507(12) 50.57(3) d β− 89Y 5/2+
    90Sr[n 11] 38 52 89.907738(3) 28.90(3) y β− 90Y 0+
    91Sr 38 53 90.910203(5) 9.63(5) h β− 91Y 5/2+
    92Sr 38 54 91.911038(4) 2.66(4) h β− 92Y 0+
    93Sr 38 55 92.914026(8) 7.423(24) min β− 93Y 5/2+
    94Sr 38 56 93.915361(8) 75.3(2) s β− 94Y 0+
    95Sr 38 57 94.919359(8) 23.90(14) s β− 95Y 1/2+
    96Sr 38 58 95.921697(29) 1.07(1) s β− 96Y 0+
    97Sr 38 59 96.926153(21) 429(5) ms β− (99.95%) 97Y 1/2+
    β−, n (.05%) 96Y
    97m1Sr 308.13(11) keV 170(10) ns (7/2)+
    97m2Sr 830.8(2) keV 255(10) ns (11/2−)#
    98Sr 38 60 97.928453(28) 0.653(2) s β− (99.75%) 98Y 0+
    β−, n (.25%) 97Y
    99Sr 38 61 98.93324(9) 0.269(1) s β− (99.9%) 99Y 3/2+
    β−, n (.1%) 98Y
    100Sr 38 62 99.93535(14) 202(3) ms β− (99.02%) 100Y 0+
    β−, n (.98%) 99Y
    101Sr 38 63 100.94052(13) 118(3) ms β− (97.63%) 101Y (5/2−)
    β−, n (2.37%) 100Y
    102Sr 38 64 101.94302(12) 69(6) ms β− (94.5%) 102Y 0+
    β−, n (5.5%) 101Y
    103Sr 38 65 102.94895(54)# 50# ms [>300 ns] β− 103Y
    104Sr 38 66 103.95233(75)# 30# ms [>300 ns] β− 104Y 0+
    105Sr 38 67 104.95858(75)# 20# ms [>300 ns]
    106Sr[8] 38 68
    107Sr[8] 38 69
    108Sr[9] 38 70
    This table header & footer:
    1. ^ mSr – 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:
      EC: Electron capture
      IT:
      Isomeric transition
      n: Neutron emission
      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. ^ Believed to decay by β+β+ to 84Kr
    10. ^ Used in rubidium–strontium dating
    11. ^
      Fission product

    References

    1. doi:10.1088/1674-1137/abddae
      .
    2. ^ "Standard Atomic Weights: Strontium". CIAAW. 1969.
    3. ISSN 1365-3075
      .
    4. ISBN 978-1-107-09944-9
      .
    5. PMID 2419578
      .
    6. S2CID 99369165
      .
    7. ^ "Discovery by UMass Lowell-led team challenges nuclear theory". Space Daily. Retrieved 2022-06-26.
    8. ^
      doi:10.1143/JPSJ.79.073201
      .
    9. S2CID 234019083
      .
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