| Abstract |
We consider methods of liquid atomization for use in the generation of mono-sized nanoparticles via evaporation<p>of solvent from liquid droplets (as in spray-pyrolysis or spray-drying). Making nanoparticles with mean geometric<p>diameter between 1 & 15 nm, requires droplets that are not much larger, in order to reduce trace contamination<p>in the final residue. Also, nanosize-related effects demand tight control over the width of the droplet size<p>distribution. We thus consider the generation of drops 5 to 50 nm in diameter, via electrohydrodynamic<p>atomization (EHDA) as a basis for development of future sucessful atomization methods. This remarkable<p>technique leads to very narrow droplet size distributions, with means tunable between 100's of microns down to<p>atomic dimensions (as in liquid metal ion sources). It is also a very gentle technique (routinely used for protein<p>analysis for example), compatible with many chemistries. Applying this technique, however, requires solving the<p>constraints of its traditional implementation, the "cone-jet mode", of: (1) high electrical conductivity values, and<p>(2) low liquid flow rates per emitting point. While the importance of (2) will be dependent on applications, solving<p>(1) is of fundamental value for enabling such applications.<p>We propose that recently-reported EHDA modes of "nanospray" and "corona-assisted electrospray" offer new<p>angles that are worth investigating in this context. While the mechanisms behind each of these modes are still<p>unknown, these modes appear to be superior to the traditional "cone-jet" mode, especially in regards to the<p>challenge posed by (1). Understanding their mechanisms will be key to gaining insight about what is ultimately<p>required to fix problem (1), and is thus one of our main objectives. Another objective is to determine how new<p>implementations of these modes, by combination, or via coupling of other forms of energy (such a
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