Measuring Multiple Plasma Reactive Species in Complex Settings Using an Innovative Approach of Cavity Ringdown Spectroscopy

Low temperature plasma (LTP) has broad applications, stemming from interactions of the LTP agents (reactive species (RS), electrons, and UV light) with a targeted medium. Knowing the absolute concentration of LTP RS in time and in space remains one of the most challenging yet most important LTP diagnostic tasks. This challenge is further compounded when an LTP source is set for interactions with a wet medium, e.g., a biological surface, where the interface between the plasma gas and the liquid (or solution) forms a time- and space-dependent multiphase reaction zone (or interfacial reaction zone). To date, the behavior of the RS, such as transport and diffusion, formation and loss, etc., in this interfacial reaction zone is virtually unexplored, largely due to technical challenges. This challenge hinders our understanding the complicated physics, gas dynamics, and heterogeneous chemistry of LTP in the complex settings.