A spectroscopic study of intermediates in the condensation of refractory smokes: Matrix isolation experiments of SiO

The infrared and Raman spectra of N₂ matrix-isolated silicon oxides were investigated. The vibrational frequencies of SiO, Si₂O₂, and Si₃O₃ were identified and assigned on the basis of normal coordinate analyses. Heating the solid to ∼50 K (evaporating the matrix) leaves a residue whose infrared spectrum is identical to that of a smoke condensed at ambient temperatures. Further heating of the sample to ∼500 K leads to significant changes in the band shapes. Investigations of the infrared spectra at several stages of the diffusion process enable us to propose a mechanism for the transition from molecular properties to those of the residue (bulk) material, which has been characterized as Si₂O₃.