Silicon: isotope data
Silicon isotopes are used in a variety of applications. Si-28 has been suggested to improve the thermal conductivity of semiconductors. Si-29 is used extensively in NMR spectroscopy. Si-30 has been used to produce the radioisotope Si-31. Si-30 has also been used to study the self-diffusivity of Silicon and it has been used to study the isotope effect on superconductivity.
Naturally occurring isotopes
|Isotope||Mass / Da||Natural abundance (atom %)||Nuclear spin (I)||Magnetic moment (μ/μN)|
|28Si||27.9769271 (7)||92.2297 (7)||0||0|
|29Si||28.9764949 (7)||4.6832 (5)||1/2||-0.55529|
|30Si||29.9737707 (7)||3.0872 (5)||0||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.
|Isotope||Mass / Da||Half-life||Mode of decay||Nuclear spin||Nuclear magnetic moment|
|26Si||25.992330||2.23 s||EC to 26Al||0|
|27Si||26.9867041||4.14 s||EC to 27Al||5/2|
|31Si||30.975362||2.62 h||β- to 31P||3/2|
|32Si||31.974148||160 y||β- to 32P||0|
|33Si||32.97800||6.1 s||β- to 33P||3/2|
|34Si||33.97858||2.8 s||β- to 34P||0|
- 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]
- For further information about radioisotopes see Jonghwa Chang's (Korea Atomic Energy Research Institute) Table of the Nuclides
- 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]
Common reference compound: Si(CH3)4/CDCl3 (1%).
|Isotope 1||Isotope 2||Isotope 3|
|Natural abundance /%||4.6832|
|Frequency relative to 1H = 100 (MHz)||19.867187|
|Receptivity, DP, relative to 1H = 1.00||0.000368|
|Receptivity, DC, relative to 13C = 1.00||2.16|
|Magnetogyric ratio, γ (107 rad T‑1 s-1)||-5.3190|
|Magnetic moment, μ (μN)||-0.96179|
|Nuclear quadrupole moment, Q/millibarn||-|
|Line width factor, 1056 l (m4)||-|
- 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.
- J. Mason in Multinuclear NMR, Plenum Press, New York, USA, 1987. Where given, data for certain radioactive nuclei are from this reference.
- P. Pyykkö, Mol. Phys., 2008, 106, 1965-1974.
- P. Pyykkö, Mol. Phys., 2001, 99, 1617-1629.
- 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.
- 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.
- P. Pyykkö, personal communication, 1998, 204, 2008, 2010.