Arsenic: 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 arsenic are listed (including any which occur naturally) below.
Isotope Mass / Da Natural abundance (atom %) Nuclear spin (I) Magnetic moment (μ/μN)
75As 74.9215942 (17) 100 3/2 1.43947

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 arsenic are listed above. This table gives information about some radiosotopes of arsenic, 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
68As 67.9368 2.53 m EC to 68Ge 3
69As 68.93228 15.2 m EC to 69Ge 5/2 1.2
70As 69.93093 52.6 m EC to 70Ge 4 2.1061
71As 70.927114 2.72 d EC to 71Ge 5/2 1.6735
72As 71.926753 26.0 h EC to 72Ge 2 -2.1566
73As 72.923825 80.3 d EC to 73Ge 3/2
74As 73.923829 17.78 d β- to 74Se; EC to 74Ge 2 -1.597
76As 75.922394 26.3 h β- to 76Se 2 -0.906
77As 76.920648 38.8 h β- to 77Se 3/2
78As 77.92183 1.512 h β- to 78Se 2
79As 78.92095 9.0 m β- to 79Se 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 arsenic

Common reference compound: NaAsF6/MeCN.

Table of NMR-active nucleus propeties of arsenic
  Isotope 1 Isotope 2 Isotope 3
Isotope 75As
Natural abundance /% 100
Spin (I) 3/2
Frequency relative to 1H = 100 (MHz) 17.122710
Receptivity, DP, relative to 1H = 1.00 0.0254
Receptivity, DC, relative to 13C = 1.00 145
Magnetogyric ratio, γ (107 rad T‑1 s-1) 4.596163
Magnetic moment, μ (μN) 1.858354
Nuclear quadrupole moment, Q/millibarn 314(6)
Line width factor, 1056 l (m4) 0.13


  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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