SiH

SiH, or silicon monohydride, is the diatomic molecule formed by silicon and hydrogen. It is a reactive radical with an unpaired electron, typically described as a doublet state. In gas-phase studies, SiH is a transient intermediate encountered under high-temperature, plasma, or combustion conditions.

Structure and bonding: SiH contains a single covalent Si–H bond. The presence of an odd number of electrons makes it a radical, which accounts for its high reactivity. As a diatomic, its geometry is linear and its spectra exhibit rotational and vibrational structure characteristic of light diatomic hydrides.

Formation and occurrence: SiH is generated in flames, plasmas, and chemical vapor deposition processes where silicon-bearing species meet hydrogen. It has also been detected or inferred in certain astrophysical environments, such as regions of silicon- and hydrogen-rich gas around evolved stars.

Spectroscopy and properties: SiH has been studied by infrared, microwave, and electronic spectroscopy, yielding molecular constants and information about the potential energy curve. Its doublet ground state gives rise to fine-structure in the observed spectra, enabling researchers to characterize its bonding and dissociation behavior.

Reactivity and significance: As a reactive intermediate, SiH participates in the formation of larger silicon hydrides such as SiH2, SiH3, and silanes under appropriate conditions. In materials science, understanding SiH helps model silicon–hydrogen chemistry in deposition and etching processes, as well as certain astrochemical networks where silicon-bearing species are involved.

See also: silicon hydrides, SiH2, SiH3, silane.