Bipolar charging and neutralization of nanometer-sized aerosol particles

Alonso, M.; Kousaka, Yasuo; Nomura, Toshiyuki; Hashimoto, Noritsugu; Hashimoto, Tadanori

doi:10.1016/s0021-8502(97)00036-0

Cited by 48 publications

(28 citation statements)

References 15 publications

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“…As a result, the values of ion mass and mobility reported in the aerosol charging literature lie within a considerable wide range of values, in spite that in most of the works the ion generation technique employed was the same, e.g. air ions generated from 241 Am (Hussin et al, 1983;Wen et al, 1984;Adachi et al, 1985;Hoppel and Frick, 1986;Wiedensohler et al, 1986;Hoppel and Frick, 1990;Wiedensohler and Fissan, 1991;Alonso et al, 1997).…”

Section: Introductionmentioning

confidence: 77%

First Differential Mobility Analysis (DMA) Measurements of Air Ions Produced by Radioactive Source and Corona

Alonso¹,

Santos

Hontañón

et al. 2009

Aerosol Air Qual. Res.

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A recently developed Differential Mobility Analyzer (DMA) of high resolving power (50 for ions of mobility equivalent diameter∼1 nm) has been used to measure the mobility distribution of laboratory air ions generated by 241 Am and corona discharge. In the case of 241 Am, it has been possible to follow the changes in mobility during the early stages of ion aging: within the time interval between 10 and 30 ms after ion formation, the mean reduced mobility of positive ions decreased from 1.30 to 1.15 cm 2 /Vs, and that of negative ions from 2.0 to 1.75 cm 2 /Vs. The mobility distribution of air ions at the outlet of a corona ionizer strongly depends on the corona voltage, mainly due to the mobility-dependent extent of electrostatic losses within the ionizer. The mean reduced mobility of corona ions ranged between 1.01 and 1.20 cm 2 /Vs (positive) and 1.76 and 1.96 cm 2 /Vs (negative).

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Section: Introductionmentioning

confidence: 77%

First Differential Mobility Analysis (DMA) Measurements of Air Ions Produced by Radioactive Source and Corona

Alonso¹,

Santos

Hontañón

et al. 2009

Aerosol Air Qual. Res.

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“…Nevertheless, whether particles (or macromolecules) smaller than 2.5 nm are fully charged to the Fuchs' charge distribution is still controversial. One study examining WO x particles found good agreement with Fuchs' theory at the smallest size measured (2 nm) (Reischl et al 1996), but another study examining NaCl particles measured a charge fraction that was significantly lower than Fuchs' one for particles smaller than 2.5 nm (Alonso et al 1997). Obviously, if the actual charging efficiency is significantly lower than the assumed one, measurements using a commercial charger would be underestimating the number of particles.…”

Section: Introductionmentioning

confidence: 92%

“…Several works examined the charge distribution attained by ultrafine aerosols when mixed with a bath of bipolar ions at room temperature in order to accurately determine the charging efficiency of commercial diffusion chargers (Adachi, et al 1985;Alonso et al 1997;Hoppel and Frick 1986;Reischl et al 1996;Wiedensohler 1988;Wiedensohler and Fissan 1988). Ion-particle combination coefficients for diffusion charging are calculated differently in three regimes according to the 652 L.A. SGRO ET AL.…”

Section: Introductionmentioning

confidence: 99%

“…In the transition regime (Kn ∼ 1 or d ∼ λ i ), a semi-phenomenological approach is often employed: the continuum theory, described by the diffusion-mobility equations, describe ion transport outside a limiting sphere surrounding the particles at a distance on the order of λ i , the free molecule transport equation is considered inside the sphere, and the two fluxes are matched at the surface of the limiting sphere (Fuchs 1963;Hoppel and Frick 1986). The last theory, first developed by Fuchs, seems to reproduce experimental results at atmospheric conditions for particles as small as 2.5 nm (Adachi et al 1985;Alonso et al 1997;Hoppel and Frick 1986;Reischl et al 1996;Wiedensohler 1988;Wiedensohler and Fissan 1988), even though such small particles are in the free molecular regime (Kn ∼ 30). Following these studies, the charging efficiency of commercial particle bipolar diffusion chargers is calculated assuming the Fuchs' steady-state charge distribution.…”

Section: Introductionmentioning

confidence: 99%

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Charge Distribution of Incipient Flame-Generated Particles

Sgro

D’Anna

Minutolo

2010

Aerosol Science and Technology

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We report the size and electrical charge distributions of incipient nanoparticles generated in atmospheric pressure hydrocarbon/air premixed flames in conditions prior to the onset of soot particles. The particle size and charge distributions are measured by Differential Mobility Analysis (DMA) and compared to theoretical charge distributions predicted for flame conditions. The results show that the charge distribution attained in flames is well predicted by Boltzmann theory for all particles, including even the smallest incipient particles with diameters in the 1-3 nm size range. In flame conditions that produce only particles smaller than 3 nm, the charge fraction of particles agrees with that predicted by Boltzmann theory near the flame temperature (1700 K). In flame conditions with 'bimodal' particle size distributions, the charge fraction of the smallest particles agrees with the Boltzmann prediction at maximum flame temperature, while the charge fractions of larger particles agree with Boltzmann theory at temperatures that coincide with the local temperature near the probe surface (1000-1200 K). The results of this paper show that the temperature of the Boltzmann charge fraction that best agrees with the measured charge fraction for each particle size gives the local temperature of their last coagulation event. The smaller particles, which retain their charge fraction predicted by Boltzmann at the maximum flame temperature, do not thermalize by coagulation in the cool region near the probe evidencing low probability for charge transfer as well as for coagulation.

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“…62·10 -8 Hoppel and Frick (1986) 1.20·10 -4 150 3.03·10 -6 203.3 1. 44·10 -8 Hoppel and Frick (1990), Reischl et al (1996) 1.33·10 -4 200 3.36·10 -6 176.1 1.63·10 -8 Wiedensohler and Fissan (1991) 1.40·10 -4 140 3.54·10 -6 210.5 1.67·10 -8 Alonso et al (1997), Alonso et al (2002) 1.15·10 -4 150 2.91·10 -6 203.3 1.38·10 -8 Alguacil and Alonso (2006) 1.10·10 -4 200 2.78·10 -6 176.1…”

Section: Governing Equations For Unipolar Diffusionmentioning

confidence: 99%