Spectral characterization for small clusters of silicon and oxygen: SiO2, SiO3, Si2O3, & Si2O4

Rocky bodies are made of minerals comprised largely of silicon and oxygen. How these minerals are formed from their constituent atoms is not fully known. The rovibrational IR spectral data produced in this work may help to observe small molecules containing silicon and oxygen so that these potential molecular intermediates can be observed. These molecules have strong absorption features between 7.0 ​μm and 8.0 ​μm, most notably, and are fully characterized in the IR from the present quantum chemical data. The antisymmetric Si−O stretches of small silicon oxide clusters also fall in this range and have large intensities. Hence, this quantum chemical analysis provides spectral data for such molecules that may be of significance for astrochemical classification and could play a role in the formation or degradation of mineral nanocrystals from or into their constituent atoms. Both explicitly computed anharmonic fundamental vibrational frequencies and those determined from scaled harmonic frequencies agree well with known experimental data, and spectroscopic constants are provided herein such that astronomical rotational spectral characterization may also be possible for the C2v SiO3 and Si2O3 molecules.