Experimental observation of liquid phase short-lived reactive species by advection system in contact with atmospheric pressure plasma *

 Novel applications of non-equilibrium atmospheric pressure plasmas (APPs) in a liquid or in contact with a liquid have been found in the life science field (e.g., biology, medicine, agriculture). These applications employ APP as a source to deliver the reactive oxygen and nitrogen species (RONS) to the liquid phase. However, much of the RONS chemistry at the plasma-liquid interface has not been understood, notably liquid-phase OH radical (OH_aq) has hardly been characterized in experiments due to their high reactivity and non-uniformity at the interface.  To break through this problem, we built an APP system with a high-speed liquid flow (over 10 m/s) through plasma, which gives an OH_aq advection system. This advection system revealed very rapid OH_aq decay within approximately 0.5 ms after the plasma exposure and an acceleration of the OH_aq decay with the 0.5% N₂ admixture to helium. In the presentation, the detail OH_aq detection process by the advection system including the measurement accuracy will be discussed quantitatively.