Selective production of reactive oxygen and nitrogen species in the plasma-treated water by using a nonthermal high-frequency plasma jet

We present the control of H2O2 and NO2- productions in deionized water by using a high-frequency plasma jet driven by a 60 MHz voltage. In the gas phase, the high-frequency plasma jet has a high O(P-3) atom density of 8 x 10(14) cm(-3), which is two orders of magnitude higher than that of the low-frequency plasma jet driven by a 5 kHz voltage. Concerning the production of reactive oxygen and nitrogen species in the liquid phase, with the direct contact of the plasma jet to the liquid surface, the H2O2 concentration is higher than the NO2- concentration. On the other hand, without the observable contact of the high-frequency plasm jet with high plasma density to the liquid surface, the NO2- concentration increases with the flow rate of N-2(20%)O-2(80%) gas added to the Ar discharge gas and becomes more dominant compared with H2O2 in the plasma-treated water. H2O2 and NO2- could be selectively produced in the plasma-treated water by using a nonthermal high-frequency plasma jet, which is a promising tool for biomedical applications. (C) 2018 The Japan Society of Applied Physics