EXPRESS: Imaging Spectroscopy at the Plasma-Liquid Interface.

This contribution presents a novel, simple and cost-effective method for observing the movement of reaction products out of the plasma-liquid interface (PLI). By employing an imaging spectrograph, a multidimensional view, i.e., spatial, spectral, and temporal, of reactions occurring at the PLI is made possible, including the ability to track the reactions from the interface to bulk. Ultraviolet-visible (UV-Vis) absorption spectroscopy techniques are key for interpreting changes in the observed section, and these techniques allow for calculating concentrations, determining production rates, and identifying reaction pathways. We describe and specify a direct vision imaging spectrograph and demonstrate its application to the aforementioned task. This approach provides valuable insight into the dynamics at the PLI and is a promising method for studying reaction kinetics and mechanisms in similar systems. Imaging spectroscopy is a valuable tool for analyzing the spatial, spectral, and temporal dynamics of plasma-liquid interactions. Our findings provide new insights into the complex physical and chemical processes which occur in such systems; they offer a deeper understanding of plasma-induced phenomena at the liquid interface. As a consequence, this research furthers possibilities for optimizing plasma-driven chemical reactions.