Measurement and analysis of the ν4 band of silane

The ν₄ band of silane has been recorded with a resolution of about 0.06 cm⁻¹ in the region from 850 to 950 cm⁻¹. Assignments of all allowed transitions in this range with J′ ≤ 12 have been made on the basis of frequency and relative intensity. Qualitative agreement with theory is good but quantitative agreement begins to break down above J′ = 8. The breakdown is attributed to the effects of the strong Coriolis interaction with nearby ν₂.Lines of ²⁹SiH₄ and ³⁰SiH₄ have been observed in the R branch with constant isotope shifts of −1.334 cm⁻¹ and −2.600 cm⁻¹.