Assessing solvated electron uptake in low-temperature plasma-exposed solutions as a pathway to quantifying plasma electrons.

Low-temperature plasma (LTP) is being advanced as an alternative radiation source that offers unique chemical properties demonstrated in a variety of reactive plasma species, in which electrons are the primary species derived upon plasma irradiation. We employed a simple and reliable protocol based on two-electron reduction of nitrate into nitrite ions coupled with fluorometric detection to quantify the uptakes of solvated electrons in irradiated solutions under two distinct plasma conditions of our LTP source. In addition, we explored the influence of other plasma species and the solution pH on the uptake rates. Under such conditions, the estimated uptake of solvated electrons was below 0.1 mM, suggesting that this value represents the minimum concentration of plasma electrons transferred to the solution. Quantifying plasma electrons accurately is particularly important for LTP applications that involve biological molecules, as they are susceptible to damage by low-energy electrons.