Molecular absorption spectroscopy of the atmospheric pressure air DBD

Summary form only given. Recently, the use of non-equilibrium high pressure plasmas in material processing has witnessed a spectacular growth. This is due to the fact that these plasmas are practical and economical sources of chemically reactive species. Identification and measurement of the concentrations of those species is essential for the optimization of the treatment process. Dielectric barrier discharges, in particular, are attractive sources due to their simplicity and stability. In our experimental setup the plasma is ignited between two alumina plates, separated by 6 mm gap. The active species generated in the discharge are transferred by the gas flow (varying from 0 to 10 l/min) to the adjacent compartment, where the sample under treatment is located. Earlier, the optical emission study of this discharge was done in terms of relative OH, NO, O, N/sub 2/, and N/sub 2//sup +/ concentrations in the plasma. This work is devoted to the measurement of the absolute concentrations of nitric oxides (NO/sub x/) and ozone for different plasma operating conditions by means of absorption spectroscopy. Since the bands of ozone and NO/sub 2/ are overlapping, the absolute ozone concentration is also measured independently by means of iodometric titration. A Xenon 300 W ozone-free lamp was chosen to be a light source for absorption measurements due to its almost constant spectral irradiance in the UV-visible wavelength range.