Control of nanoparticle charge via condensation magnification

Enhanced unipolar charging of concentration-enriched particles using water-based condensational growth

“…The saturation value in the number of charges per particle (q max ) is reached at a certain electric field (E max ) on the surface of the particle with diameter D p according to the following equation: E max ∼ q max /D 2 p . The electric field in our study is far lower (E = 0.03.0.1 V/nm) compared with those reported in previous studies (about 1.0 V/nm in Loscertales & Fernandez de la Mora (1995) and about 0.5-0.6 V/nm in Kim, Lee, et al (2006) and ). Therefore, larger droplet sizes probably lead to higher number of charges per particle for PSL particles tested in this study.…”

“…Furthermore, the average droplet size to which particles grow, by condensation in the VACES, is influenced to some degree by the particle concentration, as presented in Table 1; a higher particle concentration results in a smaller droplet size (because excess vapor concentration available for condensation is shared by a greater number of particles), which also probably affects the number of charges acquired per particle. In a previous study by Kim, Lee, et al (2006), , the number of charges per particle increased with increasing droplet size, and reached a saturation (maximum) value at a droplet size of about 1.0 m. Even though the droplet size is much larger (i.e. about 3 m) in our study, the number of charges per particle does not appear to be reaching saturation because of the relatively larger size of PSL particles compared with those (12-25 nm) used in Kim, Lee, et al (2006).…”

“…In a previous study by Kim, Lee, et al (2006), , the number of charges per particle increased with increasing droplet size, and reached a saturation (maximum) value at a droplet size of about 1.0 m. Even though the droplet size is much larger (i.e. about 3 m) in our study, the number of charges per particle does not appear to be reaching saturation because of the relatively larger size of PSL particles compared with those (12-25 nm) used in Kim, Lee, et al (2006). The saturation value in the number of charges per particle (q max ) is reached at a certain electric field (E max ) on the surface of the particle with diameter D p according to the following equation: E max ∼ q max /D 2 p .…”

“…Efficient charging of particles is one of the most useful methods for kinetic manipulation, sampling and control of airborne particles (Jacobs, Campbell, & Steward, 2002;Kang et al, 2004;Kim, Lee, Woo, & Choi, 2006;Krinke, Fissan, Deppert, Magnusson, & Samuelson, 2001). Diffusion or field chargers have been developed based on radioactive rays and corona discharge.…”

Development of Semicontinuous Measurement System of Ionic Species in PM2.5

“…The sizes of particles increase due to the spontaneous absorption of water at RHs higher than the deliquescence relative humidity (DRH) and the masses of water-absorbed samples also increase significantly. 18,[24][25][26][27] The RH in the chamber was ~ 300% under the following experimental conditions: an air sample flow rate of 16.7 L min , and a 110 o C steam temperature. Water-absorbed particles can be impacted efficiently on the inner surface of the helix coil due to both an inertial force, enhanced by the increase in aerosol mass, and a centrifugal force, caused by movement through the curvature.…”