Influence of humidity on photochemical ozone generation with 172 nm xenon excimer lamps

The reaction kinetics of photochemical ozone (O3) generation in humid air and oxygen (O2) using efficient, narrow band vacuum ultra violet (VUV) 172 nm xenon excimer lamps is discussed. Trace amounts of water (H2O) vapor in the process gas leads to hydroxyl (OH) and hydroperoxy (HO2) radical formation. These radicals drive a catalytic O3 destruction cycle limiting O3 saturation concentration. This catalytic O3 destruction cycle was included into a quantitative kinetic model describing photochemical O3 production. Experimental O3 saturation concentrations obtained with coaxial VUV driven photochemical O3 generators compare satisfactorily with the models predictions.