Isotopes of neodymium

Naturally occurring Neodymium (Nd) is composed of 5 stable isotopes, ¹⁴²Nd, ¹⁴³Nd, ¹⁴⁵Nd, ¹⁴⁶Nd and ¹⁴⁸Nd, with ¹⁴²Nd being the most abundant (27.2% natural abundance), and 2 radioisotopes, ¹⁴⁴Nd and ¹⁵⁰Nd. In all, 31 radioisotopes of Neodymium have been characterized up to now, with the most stable being naturally occurring isotopes ¹⁴⁴Nd (alpha decay, a half-life (T_½) of 2.29×10¹⁵ years) and ¹⁵⁰Nd (double beta decay, T_½ of 7×10¹⁸ years). All of the remaining radioactive isotopes have half-lives that are less than 11 days, and the majority of these have half-lives that are less than 70 seconds. This element also has 13 known meta states with the most stable being ^139mNd (T_½ 5.5 hours), ^135mNd (T_½ 5.5 minutes) and ^133m1Nd (T_½ ~70 seconds).

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The primary decay modes before the most abundant stable isotope, ¹⁴²Nd, are electron capture and positron decay, and the primary mode after is beta minus decay. The primary decay products before ¹⁴²Nd are element Pr (praseodymium) isotopes and the primary products after are element Pm (promethium) isotopes.
Standard atomic mass: 144.242(3) u

Table

Notes

• Evaluated isotopic composition is for most but not all commercial samples.
• 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

• Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
• Isotopic compositions and standard atomic masses from Atomic weights of the elements. Review 2000 (IUPAC Technical Report). Pure Appl. Chem. Vol. 75, No. 6, pp. 683-800, (2003) and Atomic Weights Revised (2005).
• Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
  • Audi, Bersillon, Blachot, Wapstra. The Nubase2003 evaluation of nuclear and decay properties, Nuc. Phys. A 729, pp. 3-128 (2003).
  • National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the NuDat 2.1 database (retrieved Sept. 2005).
  • David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.