Roles of oxidizing species in a nonequilibrium atmospheric-pressure pulsed remote O_2/N_2 plasma glass cleaning process

摘要

Atmospheric pressure plasma treatments have attracted attention for various application processes. The effect of O_2 additions below 0.2% to N_2 was investigated for the efficiency of removing organic contaminants on a glass surface using nonequilibrium atmospheric-pressure pulsed plasma. A remarkably high efficiency of cleaning was obtained by a plasma treatment with ca. 0.03% O_2 additions to N_2. The concentration of ozone (O_3) and the ground-state oxygen radical [O(~3P_2)] were measured using ultraviolet absorption spectroscopy and vacuum ultraviolet laser absorption spectroscopy, respectively. It was found that the key factors for surface cleaning were the scission of carbon bonds due to ultraviolet irradiation and subsequent oxidation due to O(~3P), and that the surface cleaning proceeded in broad areas due to the photodissociation of O_3.