Solvating Electrons in Liquid Ammonia using Atmospheric-Pressure Plasma

The production of solvated electrons at the plasma/liquid interface is an important and little-understood part of many atmospheric-pressure plasma applications. In liquid ammonia, solvated electrons have a lifetime of days, compared to that of microseconds in water. Their broad absorption band provides a way to measure the concentration of solvated electrons, but the signal from one plasma pulse is often negligible. Long lifetimes in ammonia allow a large cumulative signal to be detected even if the number of electrons injected in each plasma pulse is too small to measure. We use repeating nanoseconds-long high-voltage pulses to inject current into a liquid ammonia anode and collect absorption data at 1550nm as a function of time. We present our setup and preliminary measurements of solvated electron concentration.