The absorption spectrum of solvated electrons in non-aqueous media at the plasma liquid interface

Non-equilibrium plasmas in contact with a liquid can produce a myriad of highly reactive free radicals such as electrons, hydroxyl ions, and reactive oxygen species. These radicals can drive useful solution-phase chemistry but will also recombine with themselves and the solvent in aqueous solutions, inhibiting efficiency of the target reaction. Non-aqueous solvents offer an alternative media for solution phase chemistry, where recombination of solvated electrons with the solvent are slow or non-existent. The interfacial behavior of plasma electrons when delivered into non-aqueous solutions has been so far unexplored. In this work, we aim to map out the absorption peaks of solvated electrons in alcohol/water solutions over percentages ranging from no alcohol (0%) to pure alcohol (100%) using an in-situ diagnostic technique to interrogate solvated electrons at a plasma-liquid interface known as total internal reflection absorption spectroscopy (TIRAS). Using glycerol and ethylene glycol as model alcohols, we measure the absorption behavior of plasma-solvated electrons at different wavelengths (532, 635, and 710 nm) and alcohol concentrations (0%, 7%, 14%, 30% 51%, 75%, 85%, 100% by volume). These measurements are compared to absorption behavior of pulse radiolysis-produced solvated electrons to assess the overall behavior of plasma-solvated electrons in alcohol solutions.