28Si

28Si is a stable isotope of silicon with mass number 28. Its nucleus contains 14 protons and 14 neutrons, giving an equal number of protons and neutrons. The ground-state spin is 0+, and it is non-radioactive.

Natural silicon is dominated by 28Si, which accounts for about 92% of isotopic abundance. The remaining silicon in nature consists mainly of 29Si (~5%) and 30Si (~3%). This isotopic distribution is useful in various scientific applications, including precision measurements and materials science.

In astrophysics, 28Si is produced in stars during late stages of stellar evolution. It forms through alpha-capture processes in helium-burning shells (for example, 24Mg(α,γ)28Si) and plays a role in the silicon-burning phase that builds up heavier elements in massive stars.

Because 28Si has zero nuclear spin, isotopically enriched silicon-28 is valuable in research and technology to reduce magnetic noise and decoherence in quantum devices. In contrast, 29Si has a nonzero nuclear spin, which can interact with quantum spins in silicon-based systems. This property makes 28Si particularly attractive for high-purity semiconductor materials and for experiments requiring minimal nuclear-spin interactions.

In materials science, isotopic composition can influence lattice dynamics and thermal conductivity. Enriched 28Si crystals are used to study phonon behavior and to improve the performance of certain high-precision devices.

Summary: 28Si is the most abundant stable silicon isotope, with 14 protons and 14 neutrons, and a spin of zero. It has broad relevance in nuclear physics, astrophysics, materials science, and quantum technology.