  The charge/mass distribution f(q/m) of nanodrops and ions electrosprayed in
vacuum from mixtures of formamide (FM) and methylammonium formate (MAF) is
studied by time of flight mass spectrometry at MAF/FM volumetric concentrations
of 5%, 10%, 25% and 50%. Positive and negative polarities yield comparable
f(q/m) curves, though the negative mode yields ~30% larger currents. On
shifting from the highest to the lowest liquid flow rates, at which a cone-jet
is stable, the more conducting solutions evolve from mostly drop to primarily
ion emission. A purely ionic regime is not reached under any condition, but the
drops achieve unusually high q/m. As a result, these sprays have excellent
electrical propulsion characteristics, some being able to cover a 25-fold range
of average q/m with a propulsive efficiency typically in the range of 80%.
Results of formamide electrolytes with formates and nitrates of several other
amines are more briefly reported.
