Diode laser-aided diagnostics of a low-pressure dielectric barrier discharge applied in element-selective detection of molecular species

A small, low-pressure dielectric barrier discharge used as a detector for the analysis of halogenated hydrocarbons was studied by diode laser absorption spectroscopy of excited plasma atoms. The distribution, as well as diffusion of the excited atoms, was measured with high spatial and temporal resolution. The major part of the excited atoms was found in a very narrow discharge volume, where the maximum gas temperature and electron density, determined from broadening of the absorption line profiles, were approximately 1000 K and greater than 1015 cm−3, respectively.