Electrodynamic Levitation of Particles

Davis, E. James

doi:10.1002/9781118001684.ch19

Cited by 12 publications

(19 citation statements)

References 55 publications

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“…The assumption is reasonable in the case of highly charged droplets and droplet residuals, since they interact strongly with the AC-field and thus drift efficiently into the close proximity of the focus spot. Setting the offset parameter to r ¼ 0 and solving Equation (6) as a function of the stability parameters, earlier studies have presented multiple instability regions similar to the ones solved and presented in Figure 3 (e.g., Davis 2011;Davis 1985;Frickel, Shaffer, and Stamatoff 1978;Hartung and Avedisian 1992). In these unstable regions, the AC-field causes a highly charged particle to oscillate violently and escape from the trap.…”

Section: Electrodynamic Balancementioning

confidence: 67%

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Toward elemental analysis of ambient single particles using electrodynamic balance and laser-induced breakdown spectroscopy

Heikkilä

Rossi

Rostedt

et al. 2020

Aerosol Science and Technology

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In this article, we present a novel method for the elemental analysis of airborne aerosol particles using electrodynamic balance (EDB) trapping followed by laser-induced breakdown spectroscopy. The setup consists of a newly designed corona-based aerosol charger, doublering electrodynamic balance trap and optical arrangement for the spectroscopy. Experimental laboratory measurements using the method show that the minimum particle size for successful analysis is 1 mm in diameter, and the minimum airborne concentration is of the order of 1 particle/cm 3. In addition to the method, we will present results on the charging efficiency of the developed charger and novel stability analysis of the EDB at the charge region. The results from the stability analysis will ease the way toward analyzing submicron particles with the technique.

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Section: Electrodynamic Balancementioning

confidence: 67%

“…defines the oscillation amplitude if the DC-voltage is not correctly set to balance external forces (Davis 2011). Other terms in Equations (5) and (6) are g, which is the dynamic viscosity of the carrier gas, d p is the diameter of the particle, m its mass, q its electric charge and C c is the slip correction factor.…”

Section: Electrodynamic Balancementioning

confidence: 99%

Toward elemental analysis of ambient single particles using electrodynamic balance and laser-induced breakdown spectroscopy

Heikkilä

Rossi

Rostedt

et al. 2020

Aerosol Science and Technology

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“…As a single particle levitation technique, the Electrodynamic Balance (EDB) is capable of trapping charged droplets in an electrical field and measuring the time-dependence of parameters such as droplet size and composition 27,28 . By fitting the time-dependent size using an appropriate model, the physical properties of materials, e.g.…”

Section: Introductionmentioning

confidence: 99%

“…By fitting the time-dependent size using an appropriate model, the physical properties of materials, e.g. vapour pressure, evaporation coefficient, diffusion coefficient and hygroscopicity, can be measured 28 . Indeed, we have used the EDB technique previously to explore the evaporation kinetics of pure water droplets, estimating the vapour pressure of pure water down to 248 K 20 and determining limits for the evaporation coefficient 14,20 , assumed equal to the mass accommodation coefficient by microscopic reversibility.…”

Section: Introductionmentioning

confidence: 99%

The evaporation kinetics of pure water droplets at varying drying rates and the use of evaporation rates to infer the gas phase relative humidity

Miles

et al. 2018

Phys. Chem. Chem. Phys.

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Numerous analytical models have been applied to describe the evaporation/condensation kinetics of volatile components from aerosol particles for use in many applications. However, the applicability of these models for treating cases that lead to substantial and rapid changes in particle temperature due to, for example, evaporative cooling remain to be compared with measurements. We consider three typical treatments, comparing predictions of the evaporation rates of pure water droplets over a wide range in gas phase relative humidity (RH) and exploring the sensitivity of the predictions to uncertainties in the thermophysical gas and condensed-phase parameters. We also compare predictions from the three treatments to measurements of the evaporation rates of pure water droplets with varying RH using an electrodynamic balance (EDB), concluding that only two of the model treatments are sufficiently able to account for the level of evaporative cooling (typically as high as 12 K). Finally, we show that the RH can be inferred accurately from the evaporation rate of pure water droplets over the full range in accessible RH and comparison with the model predictions (within absolute uncertainties of 2.5% RH over the range 20% to 95% RH), considering the level of agreement with independent measurements made through determining the equilibrated size of aqueous sodium chloride and sodium nitrate droplets.

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“…Immediately after particle introduction into the EDB, "spring point" measurements were made to determine initial diameter (Davis, 2001). The spring point method is based on the equations describing the stability regions of the EDB.…”

mentioning

confidence: 99%

Electrodynamic balance–mass spectrometry of single particles as a new platform for atmospheric chemistry research

Birdsall

Krieger²,

Keutsch

2018

Atmos. Meas. Tech.

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Abstract. New analytical techniques are needed to improve our understanding of the intertwined physical and chemical processes that affect the composition of aerosol particles in the Earth's atmosphere, such as gas-particle partitioning and homogenous or heterogeneous chemistry, and their ultimate relation to air quality and climate. We describe a new laboratory setup that couples an electrodynamic balance (EDB) to a mass spectrometer (MS). The EDB stores a single laboratory-generated particle in an electric field under atmospheric conditions for an arbitrarily long length of time. The particle is then transferred via gas flow to an ionization region that vaporizes and ionizes the analyte molecules before MS measurement. We demonstrate the feasibility of the technique by tracking evaporation of polyethylene glycol molecules and finding agreement with a kinetic model. Fitting data to the kinetic model also allows determination of vapor pressures to within a factor of 2. This EDB-MS system can be used to study fundamental chemical and physical processes involving particles that are difficult to isolate and study with other techniques. The results of such measurements can be used to improve our understanding of atmospheric particles.

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Electrodynamic Levitation of Particles

Cited by 12 publications

References 55 publications

Toward elemental analysis of ambient single particles using electrodynamic balance and laser-induced breakdown spectroscopy

Toward elemental analysis of ambient single particles using electrodynamic balance and laser-induced breakdown spectroscopy

The evaporation kinetics of pure water droplets at varying drying rates and the use of evaporation rates to infer the gas phase relative humidity

Electrodynamic balance–mass spectrometry of single particles as a new platform for atmospheric chemistry research

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