Infrared and Ultraviolet Spectra of the Products of the Vacuum-Ultraviolet Photolysis of Silane Isolated in an Argon Matrix

Abstract

The vacuum‐ultraviolet photolysis of silane and of the various deuterosilanes isolated in an argon matrix at 4 or at 14°K leads to the production of several reactive species. Infrared and ultraviolet spectroscopic evidence is presented indicating that Si₂, SiH, SiH₂ and SiH₃ are stabilized in these experiments. A previously unobserved transition of Si₂, tentatively identified as the ${\mathrm{D(}}^3{\Pi }_u{\mathrm{)\hspace{0.17em}-\hspace{0.17em}X(}}^3{\Sigma }_g^{-})$ transition, is reported. Observation of the bending vibration absorption of SiH₂ at 1008 cm⁻¹ has confirmed that the lower state of the previously observed electronic transition of singlet SiH₂ is the ground state of this species. The stretching vibrations of SiH₂ have also been observed near 2000 cm⁻¹. Infrared absorptions at 925, 996, 1955, and 1999 cm⁻¹ have been tentatively assigned to SiH₃. The removal of one or more H atoms from SiH₄ leads to an appreciable lengthening of the remaining Si–H bonds. Disilane and incompletely characterized products of its photolysis contribute significantly to the infrared spectra observed at 14°K.