Precursor solutions of Al(NO3)3•9H2O (98%, Alpha Aesar) were injected into the plasma flame from a pressurized reservoir (4 bars, Sartorius 16274) through a sprayer with adjustable nozzle diameter and opening angle. As solvent, deionized water, ethanol and water-ethanol mixtures were used. A photograph of the spray being injected into the oxygen plasma flame is provided in Figure .