## Isotopes of neptunium

### 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 neptunium are listed (including any which occur naturally) below.
Isotope Atomic mass (ma/u) Natural abundance (atom %) Nuclear spin (I) Magnetic moment (μ/μN)
nil

In the above picture, 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 total 100% for all the naturally occurring isotopes.

Further data for naturally occuring isotopes of neptunium are listed above. This table gives information about some radiosotopes of neptunium, their masses, their half-lives, their modes of decay, their nuclear spins, and their nuclear magnetic moments.
Isotope Mass Half-life Mode of decay Nuclear spin Nuclear magnetic moment
234Np 234.04289 4.4 d EC to 234U 0
235Np 235.04406 1.058 y EC to 235U; α to 231Pa 5/2
236Np 236.04657 155000 y EC to 236U; α to 232Pa; β- to 236Pu 6
237Np 237.0481678 (23) 2.14 x 106 y α to 233Pa; SF 5/2 3.14
238Np 238.05094 2.117 d β- to 238Pu 2
239Np 239.05293 2.355 d β- to 239Pu 5/2

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### References

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 neptunium

Common reference compound: .

Isotope 1 Isotope 2 Isotope 237Np Natural abundance /% 0 Spin (I) 5/2 Frequency relative to 1H = 100 (MHz) 11.25 Receptivity, DP, relative to 1H = 1.00 - Receptivity, DC, relative to 13C = 1.00 - Magnetogyric ratio, γ (107 rad T-1 s-1) 3.1 Magnetic moment, μ (μN) 2.5 Nuclear quadrupole moment, Q/millibarn +3886(6) and 3850(40) [Mössbauer state] Line width factor, 1056l (m4) 5.6

### References

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.
8. The isotopic abundances are extracted from the naturally occurring isotopes section within WebElements.

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