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, O 2 and H22Oz 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 H 202 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 H 2 reduced H22O2 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.