Atmospheric pressure generation of O₂(a¹Δ_g) by microplasmas

¹ Laboratoire de Physique des Gaz et des Plasmas, UMR 8578 CNRS/Université Paris-Sud, Bât. 210, 91405 Orsay, France
² Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Avenida Rovisco Pais, 1049-001 Lisboa, Portugal
³ Laboratoire des Techniques de la Microélectronique, UMR 5129 CNRS/Université Joseph Fourier/INPG, 17 av. des Martyrs, 38054 Grenoble, France

Corresponding author: joao.santos-sousa@u-psud.fr

Received: 9 January 2009
Accepted: 6 April 2009
Published online: 5 June 2009

Abstract

The generation of singlet delta oxygen states (O₂(a¹Δ_g)) by microplasmas has been studied experimentally. In the present paper, it is shown that micro-cathode sustained discharges (MCSD's) can be used to produce high fluxes of O₂(a¹Δ_g) at atmospheric pressure. In He/O₂/NO mixtures, O₂(a¹Δ_g) number densities higher than 10¹⁶ cm⁻³ can be generated by this 3-electrode configuration and transported over distances of some tens of cm. In fact, at total flow rates up to 30 ln/min, O₂(a¹Δ_g) fluxes above 10 mmol/h were measured in the MCSD afterglow, at 26 cm downstream. As a result, MCSD's appear to be very efficient and suitable tools for the continuous production of large amounts of O₂(a¹Δ_g) at atmospheric pressure, which could give rise to a wide range of new applications, namely biological. The effect of different parameters such as gas flows and mixtures, and discharge current are discussed in the paper.