Erbium: isotope data

Erbium has six stable isotopes but only Er-168 appears to have a well established application. Er-168 is used for the production of Er-169 which is used in form of citrate for the treatment of rheumatoid arthritis.

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 erbium are listed (including any which occur naturally) below.
Isotope Mass / Da Natural abundance (atom %) Nuclear spin (I) Magnetic moment (μ/μN)
162Er 161.928775 (4) 0.14 (1) 0
164Er 163.929198 (4) 1.61 (3) 0
166Er 165.930290 (4) 33.61 (35) 0
167Er 166.932046 (4) 22.93 (17) 7/2 -0.5665
168Er 167.932368 (4) 26.78 (26) 0
170Er 169.935461 (4) 14.93 (27) 0

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 erbium are listed above. This table gives information about some radiosotopes of erbium, 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
160Er 159.92908 1.19 d EC to 160Ho 0
161Er 160.9300 3.21 h EC to 161Ho 3/2 -0.37
163Er 162.93003 1.25 h EC to 163Ho 5/2 0.557
165Er 164.930723 10.36 h EC to 165Ho 5/2 0.643
169Er 168.934588 9.40 d β- to 169Tm 1/2 0.515
171Er 170.938026 7.52 h β- to 171Tm 5/2 0.66
172Er 171.939352 2.05 d β- to 172Tm

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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 erbium

Common reference compound: .

Table of NMR-active nucleus propeties of erbium
  Isotope 1 Isotope 2 Isotope 3
Isotope 167Er
Natural abundance /% 22.95
Spin (I) 7/2
Frequency relative to 1H = 100 (MHz) about 2.88
Receptivity, DP, relative to 1H = 1.00 -
Receptivity, DC, relative to 13C = 1.00 -
Magnetogyric ratio, γ (107 rad T‑1 s-1) -0.77157
Magnetic moment, μ (μN) -0.63935
Nuclear quadrupole moment, Q/millibarn +3565(29)
Line width factor, 1056 l (m4)


  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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