Decoupling analysis of the production mechanism of aqueous reactive species induced by a helium plasma jet

Aqueous reactive species induced by gas plasmas play a dominant role in many plasma applications such as water purification and biomedicine, but their production mechanism is so far not well understood. In this paper, an experimental setup is designed to study the interaction between an AC helium plasma jet and PBS, which allows a decoupling analysis of the plasma-liquid processes on the production of aqueous reactive species. The processes include the dissolution of neutral reactive species, the electron absorption by dissolved oxygen, the deposition of positive ions, etc. Four aqueous reactive species including H₂O₂, OH and peroxynitrite (ONOOH/ONOO^-) are detected, among which the peroxynitrite should originate from the air impurity in helium. It is found that the aqueous H₂O₂ and peroxynitrite are mainly dissolved from the gas phase, the aqueous is mainly generated by the electron absorption by dissolved oxygen, and the aqueous OH is mainly generated by the deposition of positive ions.