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.