Isotopes of dysprosium

Naturally occurring dysprosium (Dy) is composed of 7 stable isotopes, ¹⁵⁶Dy, ¹⁵⁸Dy, ¹⁶⁰Dy, ¹⁶¹Dy, ¹⁶²Dy, ¹⁶³Dy and ¹⁶⁴Dy, with ¹⁶⁴Dy being the most abundant (28.18% natural abundance). 29 radioisotopes have been characterized, with the most stable being ¹⁵⁴Dy with a half-life of 3.0 million years, ¹⁵⁹Dy with a half-life of 144.4 days, and ¹⁶⁶Dy with a half-life of 81.6 hours. All of the remaining radioactive isotopes have half-lives that are less than 10 hours, and the majority of these have half-lives that are less than 30 seconds. This element also has 12 meta states, with the most stable being ^165mDy (t_½ 1.257 minutes), ^147mDy (t_½ 55.7 seconds) and ^145mDy (t_½ 13.6 seconds).

The primary decay mode before the most abundant stable isotope, ¹⁶⁴Dy, is electron capture, and the primary mode after is beta minus decay. The primary decay products before ¹⁶⁴Dy are terbium isotopes, and the primary products after are holmium isotopes.

Standard atomic mass: 162.500(1) u

Table

1. ^ Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
2. ^ Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe)
3. ^ Believed to undergo α decay to ¹⁵²Gd or β⁺β⁺ decay to ¹⁵⁶Gd with a half-life over 10¹⁸ years
4. ^ Believed to undergo α decay to ¹⁵⁴Gd or β⁺β⁺ decay to ¹⁵⁸Gd
5. ^ Believed to undergo α decay to ¹⁵⁶Gd
6. ^ Believed to undergo α decay to ¹⁵⁷Gd
7. ^ Believed to undergo α decay to ¹⁵⁸Gd
8. ^ ^{a b} Theoretically capable of spontaneous fission
9. ^ Can undergo bound-state β^- decay to ¹⁶³Ho with a half-life of 47 days when fully ionized

Notes

• Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
• Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
• Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

References

1. ^ http://www.nucleonica.net/unc.aspx
2. ^ M. Jung et al., Phys. Rev. Letts. 69, 2164 (1992) First observation of bound-state beta minus decay.

• Isotope masses from:
  • G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties". Nuclear Physics A 729: 3–128. Bibcode 2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf. 
• Isotopic compositions and standard atomic masses from:
  • J. R. de Laeter, J. K. Böhlke, P. De Bièvre, H. Hidaka, H. S. Peiser, K. J. R. Rosman and P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry 75 (6): 683–800. doi:10.1351/pac200375060683. http://www.iupac.org/publications/pac/75/6/0683/pdf/. 
  • M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry 78 (11): 2051–2066. doi:10.1351/pac200678112051. http://iupac.org/publications/pac/78/11/2051/pdf/. Lay summary. 
• Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
  • G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties". Nuclear Physics A 729: 3–128. Bibcode 2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf. 
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/. Retrieved September 2005. 
  • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0849304859.