OH radical generation by atmospheric pressure plasma and its quantitative analysis by monitoring CO oxidation

In the atmospheric chemistry, CO oxidation monitoring method has been used to measure OH radicals concentration. The application of CO oxidation monitoring method to the OH radicals measurements in a pulsed discharged plasma in argon and H₂O mixture at 1 atm was studied. The influence of the loss reaction of OH radicals could be ignored when initial CO concentration was > 2000 ppm. However, when CO concentration exceeded 1%, the CO₂ concentration began to decrease due to a decrease in the peak discharge current. Thus, the influence of loss reaction depended on the initial concentration of CO. Production of OH radicals increased when the H₂O content increased under the same specific input energy (SIE). The production of OH radicals increased with the SIE value when the H₂O content was kept constant. These results agreed with other measurement on spectroscopic analysis of OH formation in dielectric barrier discharges of Ar/O₂/H₂O.