Effect of pressure on reaction between deuterated water and thin amorphous silica films

Abstract

Abstract Nuclear reaction analysis has been used to measure deuterium content in SiO2 thin films (224–230 nm) grown in dry oxygen and treated in D2O steam at 700–930°C and 0·22–16 mbar. The deuterium profiles are nearly flat. It is argued that the deuterium is predominantly in the form of Si–OD. The OD concentration does not vary as the square root of the steam pressure, as expected, and saturates above ∼ 7 mbar. This is interpreted in terms of a decrease in the reactivity between water and silica with increasing pressure. We discuss the latter point.