Novel ion mobility analyzers and filters

Labowsky, M.; Mora, Juan Fernández de la

doi:10.1016/j.jaerosci.2005.07.001

Cited by 26 publications

(20 citation statements)

References 10 publications

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“…This work continues the work done in the past on preventing the edge disturbances in air ion measurements (Israël, 1970;Tammet, 1970;Labowsky and Fernandez de la Mora, 2006). Here, we introduce and validate a new inlet design that increases the transmission efficiency from a few percent to about 12 % for particles with a mobility diameter of 1.5 nm (9.7 × 10 −5 m 2 V −1 s −1 in mobility).…”

Section: Introductionsupporting

confidence: 61%

A new high-transmission inlet for the Caltech nano-RDMA for size distribution measurements of sub-3 nm ions at ambient concentrations

et al. 2016

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Abstract. Reliable and reproducible measurements of atmospheric aerosol particle number size distributions below 10 nm require optimized classification instruments with high particle transmission efficiency. Almost all differential mobility analyzers (DMAs) have an unfavorable potential gradient at the outlet (e.g., long column, Vienna type) or at the inlet (nano-radial DMA), preventing them from achieving a good transmission efficiency for the smallest nanoparticles. We developed a new high-transmission inlet for the Caltech nano-radial DMA (nRDMA) that increases the transmission efficiency to 12 % for ions as small as 1.3 nm in MillikanFuchs mobility equivalent diameter, D p (corresponding to 1.2 × 10 −4 m 2 V −1 s −1 in electrical mobility). We successfully deployed the nRDMA, equipped with the new inlet, in chamber measurements, using a particle size magnifier (PSM) and as a booster a condensation particle counter (CPC). With this setup, we were able to measure size distributions of ions within a mobility range from 1.2 × 10 −4 to 5.8 × 10 −6 m 2 V −1 s −1 . The system was modeled, tested in the laboratory and used to measure negative ions at ambient concentrations in the CLOUD (Cosmics Leaving Outdoor Droplets) 7 measurement campaign at CERN. We achieved a higher size resolution (R = 5.5 at D p = 1.47 nm) than techniques currently used in field measurements (e.g., Neutral cluster and Air Ion Spectrometer (NAIS), which has a R ∼ 2 at largest sizes, and R ∼ 1.8 at D p = 1.5 nm) and maintained a good total transmission efficiency (6.3 % at D p = 1.5 nm) at moderate inlet and sheath airflows (2.5 and 30 L min −1 , respectively). In this paper, by measuring size distributions at high size resolution down to 1.3 nm, we extend the limit of the current technology. The current setup is limited to ion measurements. However, we envision that future research focused on the charging mechanisms could extend the technique to measure neutral aerosol particles as well, so that it will be possible to measure size distributions of ambient aerosols from 1 nm to 1 µm.

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Section: Introductionsupporting

confidence: 61%

A new high-transmission inlet for the Caltech nano-RDMA for size distribution measurements of sub-3 nm ions at ambient concentrations

et al. 2016

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“…These include adaptations of the Knutson and Whitby DMA to produce the nanoDMA (Chen et al 1998), and the radial DMA (RDMA; Zhang et al 1995). Development has continued, enabling classification of particles as small as 1 nm (Rosell-Llompart et al 1996;Labowsky and de la Mora 2006;Brunelli et al 2009). …”

Section: Advancing Nanometer Particle Classificationmentioning

confidence: 99%

Design, simulation, and characterization of a radial opposed migration ion and aerosol classifier (ROMIAC)

Mui

Mai

Downard

et al. 2017

Aerosol Science and Technology

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We present the design, simulation, and characterization of the radial opposed migration ion and aerosol classifier (ROMIAC), a compact differential electrical mobility classifier. We evaluate the performance of the ROMIAC using a combination of finite element modeling and experimental validation of two nearly identical instruments using tetra-alkyl ammonium halide mass standards and sodium chloride particles. Mobility and efficiency calibrations were performed over a wide range of particle diameters and flow rates to characterize ROMIAC performance under the range of anticipated operating conditions. The ROMIAC performs as designed, though performance deviates from that predicted using simplistic models of the instrument. The underlying causes of this nonideal behavior are found through finite element simulations that predict the performance of the ROMIAC with greater accuracy than the simplistic models. It is concluded that analytical performance models based on idealized geometries, flows, and fields should not be relied on to make accurate a priori predictions about instrumental behavior if the actual geometry or fields deviate from the ideal assumptions. However, if such deviations are accurately captured, finite element simulations have the potential to predict instrumental performance. The present prototype of the ROMIAC maintains its resolution over nearly three orders of magnitude in particle mobility, obtaining sub-20 nm particle size distributions in a compact package with relatively low flow rate operation requirements.

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“…The distortion caused by the electric field in the inlet channel is known as the edge effect in atmospheric electric instruments (Israël 1970;Tammet 1970). Labowsky and Fernández de la Mora (2006) introduced the term isopotential to mark the DMAs where both the inlet and outlet are on the same potential and can be connected to the ground. Instruments for the research of intermediate ions in natural atmospheric air must be isopotential.…”

Section: Special Requirementsmentioning

confidence: 99%

Symmetric Inclined Grid Mobility Analyzer for the Measurement of Charged Clusters and Fine Nanoparticles in Atmospheric Air

Tammet

2011

Aerosol Science and Technology

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Novel ion mobility analyzers and filters

Cited by 26 publications

References 10 publications

A new high-transmission inlet for the Caltech nano-RDMA for size distribution measurements of sub-3 nm ions at ambient concentrations

A new high-transmission inlet for the Caltech nano-RDMA for size distribution measurements of sub-3 nm ions at ambient concentrations

Design, simulation, and characterization of a radial opposed migration ion and aerosol classifier (ROMIAC)

Symmetric Inclined Grid Mobility Analyzer for the Measurement of Charged Clusters and Fine Nanoparticles in Atmospheric Air

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Novel ion mobility analyzers and filters

Cited by 26 publications

References 10 publications

A new high-transmission inlet for the Caltech nano-RDMA for size distribution measurements of sub-3 nm ions at ambient concentrations

A new high-transmission inlet for the Caltech nano-RDMA for size distribution measurements of sub-3 nm ions at ambient concentrations

Design, simulation, and characterization of a radial opposed migration ion and aerosol classifier (ROMIAC)

Symmetric Inclined Grid Mobility Analyzer for the Measurement of Charged Clusters and Fine Nanoparticles in Atmospheric Air

Contact Info

Product

Resources

About

A new high-transmission inlet for the Caltech nano-RDMA for size distribution measurements of sub-3 nm ions at ambient concentrations

A new high-transmission inlet for the Caltech nano-RDMA for size distribution measurements of sub-3 nm ions at ambient concentrations