Isotopes of silicon

The longest-lived radioisotope is 32Si, which is produced by cosmic ray spallation of argon.

Silicon-28, the most abundant isotope of silicon, is of particular interest in the construction of quantum computers when highly enriched, as the presence of 29Si in a sample of silicon contributes to quantum decoherence.

[7] Extremely pure (>99.9998%) samples of 28Si can be produced through selective ionization and deposition of 28Si from silane gas.

[8] Due to the extremely high purity that can be obtained in this manner, the Avogadro project sought to develop a new definition of the kilogram by making a 93.75 mm (3.691 in) sphere of the isotope and determining the exact number of atoms in the sample.

[1] In addition to the usual N = 20 closed shell, the nucleus also shows a strong Z = 14 shell closure, making it behave like a doubly magic spherical nucleus, except that it is also located two protons above an island of inversion.