Matrix isolation studies on the co-condensation reactions of molecular SiO and GeO: the characterisation of the novel cyclic species SiGeO2, Si2GeO3 and SiGe2O3

Abstract

Matrix isolation IR studies, together with DFT calculations, have established that the co-condensation of molecular SiO and GeO in low temperature (12 K) nitrogen matrices leads to the formation of the novel silicon germanium oxide species SiGeO₂, Si₂GeO₃ and SiGe₂O₃ analogous to the known dimer and trimer species M₂O₂ and M₃O₃ (M = Si, Ge). Controlled diffusion studies in the temperature range 20–34 K result in a significant increase in trimer formation, which implies a very low activation energy for this oligomerisation step. Characteristic IR modes are assigned for all three novel mixed oxide molecules, and the DFT calculations establish that these species have cyclic C_2v structures and provide estimates for their geometrical parameters. The significance of these results is noted in the light of current interest in the properties of mixed Si/Ge oxide systems.