Density estimation of OH-radicals from fluorescence decay behavior near the plasma-liquid interface by LIF spectroscopy

This study addresses the challenge of detecting and quantifying short-lived OH radicals at the plasmaliquid interface. Incident microscopic laser-induced fluorescence (mLIF) was employed to observe OH-LIF signals with high spatial resolution at various moments during the post-discharge phase. The temporal evolution of OH density was quantified by fitting the OH-LIF decay to a reaction-dissolution model. The results of our investigation demonstrate that increasing the pulse width significantly enhances OH generation on the liquid surface, reaching a density of $1.25 \times 10^{\wedge} 16 \mathrm{~cm}^{\wedge}-3$. Moreover, the cathode-solution interface exhibits greater OH production compared to the anode-solution interface, underscoring the effectiveness of mLIF in quantitatively probing short-lived OH radical production at the interfacial layer in pulsed-driven plasma-solution interactions. This approach provides valuable insights into the dynamics of OH radicals and their generation at the plasma-liquid interface, contributing to a deeper understanding of the underlying processes in such interactions.