Temperature Dependence of Hydroxyl Production in the Reaction of Hydrogen with Silica Glass.

The formation of hydroxyl due to reaction of silica glass made by the modified chemical vapor deposition (MCVD) process with hydrogen has been studied for temperatures between 200C and 900C. The glass is treated under 1 atmosphere of hydrogen, which diffuses into and reacts with the glass. For treatment temperatures between 900C and 500C, spatial hydroxyl concentration profiles are measure. For treatment at 400C and below, only equilibrium OH concentrations are measured. Three temperature regimes are identified for the reaction: T > 700C, 700C > T > 400C, and T 400C. A simple model combining H sub 2 diffusion with chemical reaction explains the profile data for temperatures above 500C.