A new method for characterizing the bounce and charge transfer properties of nanoparticles

Bouncing and charge transfer between a particle and a surface are fundamental phenomena in aerosol physics. In this study, a new method is presented for characterizing these phenomena in the nanometer size range. The method is based on electrical detection of particles and on a new manner to exploit an electrical low pressure impactor (ELPI). By measuring particles with and without the charger, bouncing and charge transfer can be distinguished. To connect the measurement with the existing theoretical knowledge, a new model describing the bouncing and charge transfer behavior in a cascade impactor is presented. The model is linked to measurements through a fitting process which provides theoretical parameters for polydisperse nanoparticles. With this method, the bouncing and charge transfer of nanoparticles can be described by the existing theory of micrometer-sized particles. To demonstrate the performance of the method in practice, measurements were carried out to define the parameters for sodium chloride and levoglucosan particles.