Rubidium: isotope data

Naturally occurring isotopes

This table shows information about naturally occuring isotopes, their atomic masses, their natural abundances, their nuclear spins, and their magnetic moments. Further data for radioisotopes (radioactive isotopes) of rubidium are listed (including any which occur naturally) below.
Isotope Mass / Da Natural abundance (atom %) Nuclear spin (I) Magnetic moment (μ/μN)
85Rb 84.911794 (3) 72.17 (2) 5/2 1.35303
87Rb 86.909187 (3) 27.83 (2) 3/2 2.75124

In the above, the most intense ion is set to 100% since this corresponds best to the output from a mass spectrometer. This is not to be confused with the relative percentage isotope abundances which totals 100% for all the naturally occurring isotopes.

Radiosotope data

Further data for naturally occuring isotopes of rubidium are listed above. This table gives information about some radiosotopes of rubidium, their masses, their half-lives, their modes of decay, their nuclear spins, and their nuclear magnetic moments.
Isotope Mass / Da Half-life Mode of decay Nuclear spin Nuclear magnetic moment
81Rb 80.91900 4.57 h EC to 81Kr 3/2 2.060
82Rb 8191821 1.258 m EC to 82Kr 1 0.554508
83Rb 82.91511 86.2 d EC to 83Kr 5/2 1.425
84Rb 83.914387 32.9 d EC to 84Kr; β- to 84Sr 2 -1.32412
86Rb 85.911170 18.65 d EC to 86Kr; β- to 86Sr 2 -1.6920
87Rb 86.9091835 4.75 x 1010 y β- to 87Sr 3/2

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  1. Naturally occurring isotope abundances: Commission on Atomic Weights and Isotopic Abundances report for the International Union of Pure and Applied Chemistry in Isotopic Compositions of the Elements 1989, Pure and Applied Chemistry, 1998, 70, 217. [Copyright 1998 IUPAC]
  2. For further information about radioisotopes see Jonghwa Chang's (Korea Atomic Energy Research Institute) Table of the Nuclides
  3. Masses, nuclear spins, and magnetic moments: I. Mills, T. Cvitas, K. Homann, N. Kallay, and K. Kuchitsu in Quantities, Units and Symbols in Physical Chemistry, Blackwell Scientific Publications, Oxford, UK, 1988. [Copyright 1988 IUPAC]

NMR Properties of rubidium

Common reference compound: RbCl/D2O.

Table of NMR-active nucleus propeties of rubidium
  Isotope 1 Isotope 2 Isotope 3
Isotope 85Rb 87Rb
Natural abundance /% 72.165 27.835
Spin (I) 5/2 3/2
Frequency relative to 1H = 100 (MHz) 9.655172 32.721215
Receptivity, DP, relative to 1H = 1.00 0.00766 0.0493
Receptivity, DC, relative to 13C = 1.00 43.8 282
Magnetogyric ratio, γ (107 rad T‑1 s-1) 2.5927050 8.786400
Magnetic moment, μ (μN) 1.6013071 3.552582
Nuclear quadrupole moment, Q/millibarn 276(1) 133.5(5)
Line width factor, 1056 l (m4) 0.017 0.023


  1. R.K. Harris in Encyclopedia of Nuclear Magnetic Resonance, D.M. Granty and R.K. Harris, (eds.), vol. 5, John Wiley & Sons, Chichester, UK, 1996. I am grateful to Professor Robin Harris (University of Durham, UK) who provided much of the NMR data, which are copyright 1996 IUPAC, adapted from his contribution contained within this reference.
  2. J. Mason in Multinuclear NMR, Plenum Press, New York, USA, 1987. Where given, data for certain radioactive nuclei are from this reference.
  3. P. Pyykkö, Mol. Phys., 2008, 106, 1965-1974.
  4. P. Pyykkö, Mol. Phys., 2001, 99, 1617-1629.
  5. P. Pyykkö, Z. Naturforsch., 1992, 47a, 189. I am grateful to Professor Pekka Pyykkö (University of Helsinki, Finland) who provided the nuclear quadrupole moment data in this and the following two references.
  6. D.R. Lide, (ed.), CRC Handbook of Chemistry and Physics 1999-2000 : A Ready-Reference Book of Chemical and Physical Data (CRC Handbook of Chemistry and Physics, CRC Press, Boca Raton, Florida, USA, 79th edition, 1998.
  7. P. Pyykkö, personal communication, 1998, 204, 2008, 2010.

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