OH (X)] measurements by resonant absorption spectroscopy in a pulsed dielectric barrier discharge

Abstract

Good understanding of the different phases of the plasma-chemistry involved is essential for the development of nonthermal plasma technologies for pollution control. These techniques are often based on the dissociation of parent gases to produce radicals that, in turn, decompose the toxic compounds. Our research concerns OH radical production in a pulsed dielectric barrier discharge (DBD). OH[A 2Σ+–X 2Π(0,0)] emission in argon-water vapor gas mixtures has been studied. Particular attention has been paid to the influence of water vapor partial pressure on the lifetime and intensity of emitted fluorescence in order to develop a pulsed DBD ultraviolet light source for spectroscopic investigation. This source was used to perform OH(X 2Π) time-resolved average absolute density measurements in other DBD discharges based on resonant absorption spectroscopy. This diagnostic has been validated in argon and air-water vapor mixtures. The temporal behavior of the density OH(X 2Π) radicals after a pulse discharge has been studied in argon and air with and without 500 ppm of trichloroethylene. This simple and inexpensive tool, compared to more sophisticated laser absorption or laser-induced fluorescence measurements for plasma investigation, is very useful for characterizing the OH radical potential for pollutant oxidation.