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Naturally occurring xenon (54 Xe) consists of seven stable isotopes and two very long-lived isotopes. Double electron capture has been observed in 124 Xe (half-life 1.8 ± 0.5(stat) ± 0.1(sys) × 10 22 years) [2] and double beta decay in 136 Xe (half-life 2.165 ± 0.016(stat) ± 0.059(sys) × 10 21 years), [7] which are among the longest measured half-lives of all nuclides.
Radioactive isotope table "lists ALL radioactive nuclei with a half-life greater than 1000 years", incorporated in the list above. The NUBASE2020 evaluation of nuclear physics properties F.G. Kondev et al. 2021 Chinese Phys. C 45 030001. The PDF of this article lists the half-lives of all known radioactives nuclides.
Compared with solar xenon, Earth's atmospheric Xe is enriched in heavy isotopes by 3 to 4% per atomic mass unit (amu). [18] However, the total abundance of xenon gas is depleted by one order of magnitude relative to other noble gases. [15] The elemental depletion while relative enrichment in heavy isotopes is called the "Xenon paradox".
[1] [2] 129 Xe is a stable, naturally occurring isotope of xenon with 26.44% isotope abundance. It is one of two Xe isotopes, along with 131 Xe, that has non-zero spin, which allows for magnetic resonance. 129 Xe is used for MRI because its large electron cloud permits hyperpolarization and a wide range of chemical shifts.
Thus, 251 isotopes are stable by definition (including tantalum-180m, for which no decay has yet been observed). Those that may in the future be found to be radioactive are expected to have half-lives longer than 10 22 years (for example, xenon-134). [citation needed]
An example of an extinct radionuclide is iodine-129; it decays to xenon-129, a stable isotope of xenon which appears in excess relative to other xenon isotopes. It is found in meteorites that condensed from the primordial Solar System dust cloud and trapped primordial iodine-129 (half life 15.7 million years) sometime in a relative short period ...
Xenon has nine isotopes, most of which are produced by the radiogenic decay. Krypton and xenon noble gases requires pristine, robust geochemical sampling protocol to avoid atmospheric contamination. [118] Furthermore, sophisticated instrumentation is required to resolve mass peaks among many isotopes with narrow mass difference during analysis.
More than 40 unstable xenon isotopes undergo radioactive decay, and the isotope ratios of xenon are an important tool for studying the early history of the Solar System. [28] Radioactive xenon-135 is produced by beta decay from iodine-135 (a product of nuclear fission), and is the most significant (and unwanted) neutron absorber in nuclear ...