Generation of nanodroplets and nanoparticles by ion-induced nucleation

A charged nanodroplet generator using a sonic-jet ionizer was developed, and the size distributions and currents of ions and charged nanodroplets generated were measured. The sonic-jet ionizer produced O−2 (H2O)n ions with a high density of 109−1010 cm−3. When tetraorthosilicate (TEOS) and H2O vapors were added in the oxygen gas, the generator formed negatively charged nanodroplets with an average diameter of 1.3-1.8 and 1.3 nm, respectively. SiO2 nanoparticles synthesized from the charged TEOS nanodroplets were non-agglomerated. The size distributions measured at various furnace temperatures indicated the formation mechanism of the nanoparticles was ion-induced nucleation. To investigate sterilization effects of negatively charged H2O nanodroplets, yeast fungi were exposed to the gas flow from the charged nanodroplet generator. Survival rates of yeast were clearly reduced by the discharge.