Diagnostics of atmospheric pressure microplasma with a liquid electrode

A rf atmospheric pressure microplasma (APMP) in contact with a liquid electrode is characterized by an optical emission spectroscopy (OES) and a liquid chromatography. The results show that the solution conductivity is the essence for determining the APMP properties rather than the solution pH value. A liquid acidification observed during the APMP treatment is ascribed to the salvation of nitrogen related species created by the APMP. In addition, a typical two-sheath structure of the APMP is revealed by the spatial distribution of OES along the plasma volume. The estimated electron density of the APMP is as high as 1014–1015 cm-3