Reaction of silicon dioxide with water: a matrix isolation infrared and density functional theoretical study

Reactions of silicon dioxide with water molecules have been studied by matrix isolation infrared and density functional theoretical calculations. Silicon dioxides were prepared by reactions of laser ablated silicon atoms with oxygen in excess argon. When water molecules were added in the reagent gas, silicic acid H2SiO3 molecules were produced spontaneously on annealing. Isotopic substitution experiments showed that the H2SiO3 molecules were formed by reactions of silicon dioxide with water. The potential energy surface for silicon dioxide and water reaction was calculated. Although silicon dioxide–water complex was predicted to be stable, this complex was not observed due to low energy barrier and high exothermicity for the hydrolysis reaction.