An improved spray droplet technique for quantitative electron microscopy

Improvements are described to the spray droplet method of Backus and Williams for direct particle counting by electron microscopy. Decreasing the droplet size makes it possible to use much higher magnifications without sacrificing the ability to photograph each droplet trace entire on one frame, and droplets of the desired size are sorted and collected in a reproducible manner in a cascade impactor. The technique is also useful for studying the state of aggregation of a suspension.