Isotopes of oxygen

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Isotopes of oxygen (8O)
Main isotopes Decay
abun­dance half-life (t1/2) mode pro­duct
15O
trace 122.266 s β+100% 15N
16O 99.8%
stable
17O 0.0380% stable
18O 0.205% stable
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  • There are three known stable isotopes of oxygen (8O): 16
    O
    , 17
    O
    , and 18
    O
    .

    yoctoseconds, though half-lives have not been measured for the unbound heavy isotopes 27
    O
    and 28
    O
    .[3]

    List of isotopes

    Nuclide
    [n 1]
    Z N Isotopic mass (Da)[4]
    [n 2]
    Half-life[5]

    [resonance width]
    Decay
    mode[5]
    [n 3]
    Daughter
    isotope

    [n 4]
    Natural abundance (mole fraction)
    Excitation energy Normal proportion[5] Range of variation
    11
    O
    [6]
    8 3 11.05125(6) 198(12) ys
    [2.31(14) MeV]
    2p 9
    C
    (3/2−)
    12
    O
    8 4 12.034368(13) 8.9(3.3) zs 2p 10
    C
    0+
    13
    O
    8 5 13.024815(10) 8.58(5) ms β+ (89.1(2)%) 13
    N
    (3/2−)
    β+p (10.9(2)%) 12
    C
    β+p,α (<0.1%) 24
    He
    [7]
    14
    O
    8 6 14.008596706(27) 70.621(11) s β+ 14
    N
    0+
    15
    O
    [n 7]
    8 7 15.0030656(5) 122.266(43) s β+ 15
    N
    1/2− Trace[8]
    16
    O
    [n 8]
    8 8 15.994914619257(319) Stable 0+ [0.99738, 0.99776][9]
    17
    O
    [n 9]
    8 9 16.999131755953(692) Stable 5/2+ [0.000367, 0.000400][9]
    18
    O
    [n 8][n 10]
    8 10 17.999159612136(690) Stable 0+ [0.00187, 0.00222][9]
    19
    O
    8 11 19.0035780(28) 26.470(6) s β 19
    F
    5/2+
    20
    O
    8 12 20.0040754(9) 13.51(5) s β 20
    F
    0+
    21
    O
    8 13 21.008655(13) 3.42(10) s β 21
    F
    (5/2+)
    βn ?[n 11] 20
    F
     ?
    22
    O
    8 14 22.00997(6) 2.25(9) s β (> 78%) 22
    F
    0+
    βn (< 22%) 21
    F
    23
    O
    8 15 23.01570(13) 97(8) ms β (93(2)%) 23
    F
    1/2+
    βn (7(2)%) 22
    F
    24
    O
    [n 12]
    8 16 24.01986(18) 77.4(4.5) ms β (57(4)%) 24
    F
    0+
    βn (43(4)%) 23
    F
    25
    O
    8 17 25.02934(18) 5.18(35) zs n 24
    O
    3/2+#
    26
    O
    8 18 26.03721(18) 4.2(3.3) ps 2n 24
    O
    0+
    27
    O
    [3]
    8 19 2.5 zs n 26
    O
    (3/2+, 7/2−)
    28
    O
    [3]
    8 20 650 ys 2n 26
    O
    0+
    This table header & footer:
    1. ^ mO – Excited nuclear isomer.
    2. ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
    3. ^ Modes of decay:
      n: Neutron emission
      p: Proton emission
    4. ^ Bold symbol as daughter – Daughter product is stable.
    5. ^ ( ) spin value – Indicates spin with weak assignment arguments.
    6. ^ # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
    7. ^ Intermediate product of CNO-I in stellar nucleosynthesis as part of the process producing helium from hydrogen
    8. ^ a b The ratio between 16
      O
      and 18
      O
      is used to deduce ancient temperatures.
    9. ^ Can be used in NMR studies of metabolic pathways.
    10. ^ Can be used in studying certain metabolic pathways.
    11. ^ Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.
    12. ^ Heaviest particle-bound isotope of oxygen, see Nuclear drip line

    Stable isotopes

    Late in a massive star's life, 16
    O
    concentrates in the N-shell, 17
    O
    in the H-shell and 18
    O
    in the He-shell.

    Natural oxygen is made of three stable

    conventional value
    is 15.999).

    16
    O
    has high relative and absolute abundance because it is a principal product of

    neon burning process creates additional 16
    O
    .[10]

    Both 17
    O
    and 18
    O
    are secondary isotopes, meaning their synthesis requires seed nuclei. 17
    O
    is primarily made by burning hydrogen into helium in the
    CNO cycle, making it a common isotope in the hydrogen burning zones of stars.[10] Most 18
    O
    is produced when 14
    N
    (made abundant from CNO burning) captures a 4
    He
    nucleus, becoming 18
    F
    . This quickly (half-life around 110 minutes) beta decays to 18
    O
    making that isotope common in the helium-rich zones of stars.[10] About 109 kelvin is needed to fuse oxygen into sulfur.[11]

    An atomic mass of 16 was assigned to oxygen prior to the definition of the unified

    atomic mass unit based on 12
    C
    .[12]
    Since physicists referred to 16
    O
    only, while chemists meant the natural mix of isotopes, this led to slightly different mass scales.

    Applications of various isotopes

    Measurements of

    precipitation,[14] so Earth's freshwater and polar ice have slightly less (0.1981%) 18
    O
    than air (0.204%) or seawater (0.1995%). This disparity allows analysis of temperature patterns via historic ice cores
    .

    Solid samples (organic and inorganic) for oxygen isotopic ratios are usually stored in silver cups and measured with pyrolysis and mass spectrometry.[15] Researchers need to avoid improper or prolonged storage of the samples for accurate measurements.[15]

    Due to natural oxygen being mostly 16
    O
    , samples enriched with the other stable isotopes can be used for

    isotope labeling. For example, it was proven, that the oxygen released in photosynthesis
    originates in H2O, rather than in the also consumed CO2, by isotope tracing experiments. The oxygen contained in CO2 in turn is used to make up the sugars formed by photosynthesis.

    In

    protium) has a higher absorption cross section than any stable isotope of oxygen and its number density is twice as high in water as that of oxygen so that the effect is negligible. As some methods of isotope separation enrich not only heavier isotopes of hydrogen but also heavier isotopes of oxygen when producing heavy water, the concentration of 17
    O
    and 18
    O
    can be measurably higher. Furthermore, the 17
    O
    (n,α)14
    C
    reaction is a further undesirable result of an elevated concentration of heavier isotopes of oxygen. Therefore, facilities which remove tritium
    from heavy water used in nuclear reactors often also remove or at least reduce the amount of heavier isotopes of oxygen.

    Oxygen isotopes are also used to trace ocean composition and temperature which seafood is from.[16]

    Radioisotopes

    Thirteen

    radioisotopes have been characterized; the most stable are 15
    O
    with half-life 122.266(43) s and 14
    O
    with half-life 70.621(11) s. All remaining radioisotopes have half-lives less than 27 s and most have half-lives less than 0.1 s. Four heaviest known isotopes (up to 28
    O
    ) decay by neutron emission
    to 24
    O
    , whose half-life is 77.4(4.5) ms. This isotope, along with
    decay mode for isotopes lighter than the stable isotopes is β+ decay to nitrogen, and the most common mode after is β decay to fluorine
    .

    Oxygen-13

    Oxygen-13 is an unstable isotope, with 8 protons and 5 neutrons. It has spin 3/2−, and half-life 8.58(5) ms. Its atomic mass is 13.024815(10) Da. It decays to nitrogen-13 by electron capture, with a decay energy of 17.770(10) MeV. Its parent nuclide is fluorine-14.

    Oxygen-14

    Oxygen-14 is the second most stable radioisotope. Oxygen-14 ion beams are of interest to researchers of proton-rich nuclei; for example, one early experiment at the Facility for Rare Isotope Beams in East Lansing, Michigan, used a 14O beam to study the beta decay transition of this isotope to 14N.[18][19]

    Oxygen-15

    Oxygen-15 is a radioisotope, often used in

    nitrogen-14 using a cyclotron.[22]

    14
    N
    + 2
    H
    15
    O
    + n

    Oxygen-15 and nitrogen-13 are produced in air when gamma rays (for example from lightning) knock neutrons out of 16O and 14N:[23]

    16
    O
    + γ → 15
    O
    + n
    14
    N
    + γ → 13
    N
    + n

    15
    O
    decays to 15
    N
    , emitting a positron. The positron quickly annihilates with an electron, producing two gamma rays of about 511 keV. After a lightning bolt, this gamma radiation dies down with half-life of 2 minutes, but these low-energy gamma rays go on average only about 90 metres through the air. Together with rays produced from positrons from nitrogen-13 they may only be detected for a minute or so as the "cloud" of 15
    O
    and 13
    N
    floats by, carried by the wind.[8]

    Oxygen-20

    Oxygen-20 has a half-life of 13.51±0.05 s and decays by β decay to 20F. It is one of the known

    228Th with a branching ratio of about (1.13±0.22)×10−13.[24]

    See also

    References

    1. ^ "Standard Atomic Weights: Oxygen". CIAAW. 2009.
    2. ISSN 1365-3075
      .
    3. ^ .
    4. .
    5. ^ .
    6. .
    7. ^ Paleja, Ameya (2023-09-05). "Scientists observe nucleus decay into four particles". interestingengineering.com. Retrieved 2023-09-29.
    8. ^
      S2CID 4388159
      .
    9. ^ a b c "Atomic Weight of Oxygen | Commission on Isotopic Abundances and Atomic Weights". ciaaw.org. Retrieved 2022-03-15.
    10. ^ a b c d B. S. Meyer (September 19–21, 2005). "Nucleosynthesis and galactic chemical evolution of the isotopes of oxygen" (PDF). Proceedings of the NASA Cosmochemistry Program and the Lunar and Planetary Institute. Workgroup on Oxygen in the Earliest Solar System. Gatlinburg, Tennessee. 9022.
    11. ^ Emsley 2001, p. 297.
    12. ^ Parks & Mellor 1939, Chapter VI, Section 7.
    13. ^ Cook & Lauer 1968, p. 500.
    14. .
    15. ^ .
    16. S2CID 252173914. Archived from the original on September 13, 2022. Retrieved September 13, 2022.{{cite journal}}: CS1 maint: bot: original URL status unknown (link
      )
    17. .
    18. ^ "APS -Fall 2022 Meeting of the APS Division of Nuclear Physics - Event - Oxygen-14 Beam Production at 5 and 15 MeV/u with MARS Spectrometer". Bulletin of the American Physical Society. American Physical Society.
    19. ^ Energy, US Department of. "Researchers develop a novel method to study nuclear reactions on short-lived isotopes involved in explosions of stars". phys.org. Retrieved 16 December 2023.
    20. S2CID 72703962
      .
    21. .
    22. ^ "Production of PET Radionuclides". Austin Hospital, Austin Health. Archived from the original on 15 January 2013. Retrieved 6 December 2012.
    23. ^ Timmer, John (25 November 2017). "Lightning strikes leave behind a radioactive cloud". Ars Technica.
    24. ^ 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.