Fig. 1. Time required to deposit one nanoparticle monolayer as a function of number concentration for different particle diameters. Calculation for a nozzle-to-plane electrostatic precipitator with singly charged particles, aerosol flow rate of 1 SLM and deposit radius of 1 mm.

Fig. 2. Schematic of the spark discharge (a) and thermal evaporation (b) silicon aerosol sources used in this work.

Fig. 3. Experimental setup used to attempt the mobility classification of highly charged aerosols. In the figure FM, V, and RP stand for flow meter, valve, and rotary pump, respectively.

Fig. 4. Measurements of the aerosol net charge at different positions in an experiment using the spark-discharge source.

Fig. 5. Electrometer current as a function of the magnitude of the applied voltage in an experiment using the thermal evaporation source. (a) Effect of bypassing the neutralizer when V_RDMA<0 and (b) effect of polarity reversal for an aerosol that has bypassed the neutralizer. The traces in part (a) are log-normal fits to the data points.

Fig. 6. (a) Transmission electron microscopy image of silicon particles generated by spark discharge, run through the neutralizer and collected on a carbon substrate by hypersonic impaction after mobility classification. The voltage on the analyzer was −16 V, corresponding to a diameter of 4 nm for singly charge particles. (b) Size distribution obtained from the image (histogram). The solid lines indicate, for comparison, the RDMA transfer function as determined from tandem DMA calibration measurements (Zhang & Flagan, 1996) and from transmission electron microscopy (TEM) experiments ( Camata et al., 1996).

Fig. 7. (a) Dependence of the space-charge number with total number concentration for different electrode separations in the radial DMA. (b) Comparison between the space-charge number for the radial DMA (RDMA) and the cylindrical DMA (CDMA) for an electrode separation of 1 cm and CDMA inner electrode radius r₁=1 cm.