O2(a1Δg) production at atmospheric pressure by microdischarge

We report experimental results showing that singlet oxygen O2(a1Δg) can be efficiently produced at atmospheric pressure in a three-electrode microcathode sustained discharge (MCSD) configuration. This configuration consists of a microhollow cathode discharge (MHCD) acting as a plasma cathode to sustain a stable glow discharge between the MHCD and a third planar electrode placed at a distance of 8 mm. Experiments were performed in He/O2/NO mixtures. O2(a1Δg) number densities higher than 1016 cm-3 were measured in the MCSD afterglow at total flow rates up to 30 ln/mn, resulting in O2(a1Δg) fluxes above 10 millimole per hour (mmol/h).