current) to first desorb condensed water and then subsequently
to produce electron impact dissociation and excitation of
the desorbed water molecules at the high negative electrode
voltages.
Occasionally, we observe significant optical emissions
without corresponding large current-pulses from an individual
electrode when studying multielectrode probes. Since the
current measurements shown in Figs. 9–11 were made on one
electrode (out of as many as 18), this observation just reflects
the fact that light originates from other electrodes that are
excited simultaneously with the specific electrode that was
instrumented for current and voltage measurements.