Photolysis of Water Vapor

Abstract

The photolysis of water vapor has been studied in a flow system at rates up to 5 mole hr—1 and at temperatures up to 540°K under the influence of hydrogen discharge radiation around 1650 A. The products H2, O2 and H2O2 varied in amounts and proportions depending on the geometry of the system. Rapid removal of the products of photolysis from the reaction zone to a liquid N2 trap favored H2O2 production. Resultantly the quantum yield also varied with the geometry of the system, values from 0.03 to 0.3 were obtained. He as a diluent caused a decrease in H2O2 production. Added H2 reduced H2O2 production tenfold, accounted for by its reaction with OH. A mechanism is discussed which is substantiated by a study of the dependence of the reaction rates on light intensity.