Laboratory studies of collection efficiency of sub-micrometer aerosol particles by cloud droplets on a single-droplet basis

Abstract. An experimental setup has been constructed to measure the collection efficiency (CE) of sub-micrometer aerosol particles by cloud droplets. Droplets of a dilute aqueous ammonium sulfate solution with an average radius of 21.6 μm fall freely into a chamber and collide with sub-micrometer polystyrene latex (PSL) sphere particles of known sizes and concentrations. Two relative humidity (RH) conditions, 15 ± 3 % and 88 ± 3 %, hereafter termed "low" and "high", respectively, were varied with different particles sizes and concentrations. After passing through the chamber, the droplets and aerosol particles were sent to the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument to determine chemical compositions on a single-droplet basis. "Coagulated droplets" (droplets that collected aerosols) had mass spectra that contained signatures from both an aerosol particle and a droplet residual. CE values range from 2.0 × 10−1 to 1.6 for the low-RH case and from 1.5 × 10−2 to 9.0 × 10−2 for the high-RH case. CE values were, within experimental uncertainty, independent of the aerosol concentrations. CE values in this study were found to be in agreement with previous experimental and theoretical studies. To our knowledge, this is the first collection experiment performed on a single-droplet basis with atmospherically relevant conditions such as droplet sizes, droplet charges and flow.

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Laboratory studies of collection efficiency of sub-micrometer aerosol particles by cloud droplets on a single droplet basis

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-6207-2015 ◽

2015 ◽

Vol 15 (5) ◽

pp. 6207-6236 ◽

Cited By ~ 2

Author(s):

K. Ardon-Dryer ◽

Y.-W. Huang ◽

D. J. Cziczo

Keyword(s):

Collection Efficiency ◽

Aerosol Particles ◽

Sulfate Solution ◽

Polystyrene Latex ◽

Particle Analysis ◽

Chemical Compositions ◽

Laser Mass Spectrometry ◽

Single Droplet ◽

Cloud Droplets ◽

Experimental And Theoretical Studies

Abstract. An experimental setup has been constructed to measure the Collection Efficiency (CE) of sub-micrometer aerosol particles by cloud droplets. Water droplets of a dilute aqueous ammonium sulfate solution with a radius of ~20 μm fall freely into a chamber and collide with sub-micrometer Polystyrene Latex Sphere (PSL) particles of variable size and concentrations. Two RH conditions, ~15 and ~88%, hereafter termed "Low" and "High", respectively, were varied with different particles size and concentrations. After passing through the chamber, the droplets and aerosol particles were sent to the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument to determine chemical compositions on a single particle basis. Coagulated droplets had mass spectra that contain signatures from both an aerosol particle and a droplet residual. CE values range from 5.7 × 10−3 to 4.6 × 10−2 for the Low RH and from 6.4 × 10−3 to 2.2 × 10−2 for the High RH cases. CE values were, within experimental uncertainty, independent of the aerosol concentrations. CE values in this work were found to be in agreement with previous experimental and theoretical studies. To our knowledge, this is the first coagulation experiment performed on a single droplet basis.

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Droplet activation, separation, and compositional analysis: laboratory studies and atmospheric measurements

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-4-691-2011 ◽

2011 ◽

Vol 4 (1) ◽

pp. 691-713 ◽

Cited By ~ 1

Author(s):

N. Hiranuma ◽

M. Kohn ◽

M. S. Pekour ◽

D. A. Nelson ◽

J. E. Shilling ◽

...

Keyword(s):

Ammonium Sulfate ◽

Droplet Size ◽

Aerosol Particles ◽

Condensation Nucleus ◽

Polystyrene Latex ◽

Cloud Condensation Nucleus ◽

Particle Analysis ◽

Laser Mass Spectrometry ◽

Atmospheric Measurements ◽

Virtual Impactor

Abstract. Droplets produced in a cloud condensation nucleus chamber as a function of supersaturation have been separated from unactivated aerosol particles using counterflow virtual impaction. Residual material after droplets were evaporated was chemically analyzed with an Aerodyne Aerosol Mass Spectrometer and the Particle Analysis by Laser Mass Spectrometry instrument. Experiments were initially conducted to verify activation conditions for monodisperse ammonium sulfate particles and to determine the resulting droplet size distribution as a function of supersaturation. Based on the observed droplet size, the counterflow virtual impactor cut-size was set to differentiate droplets from unactivated interstitial particles. Validation experiments were then performed to verify that only droplets with sufficient size passed through the counterflow virtual impactor for subsequent analysis. A two-component external mixture of monodisperse particles was also exposed to a supersaturation which would activate one of the types (ammonium sulfate) but not the other (polystyrene latex spheres). The mass spectrum observed after separation indicated only the former, validating separation of droplets from unactivated particles. Results from atmospheric measurements using this technique indicate that aerosol particles often activate predominantly as a function of particle size. Chemical composition is not irrelevant, however, and we observed enhancement of sulfate in droplet residuals using single particle analysis.

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Laboratory study of the collection efficiency of submicron aerosol particles by cloud droplets. Part I – Influence of relative humidity

10.5194/acp-2020-831 ◽

2020 ◽

Cited By ~ 1

Author(s):

Alexis Dépée ◽

Pascal Lemaitre ◽

Thomas Gelain ◽

Marie Monier ◽

Andrea Flossmann

Keyword(s):

Relative Humidity ◽

High Efficiency ◽

Collection Efficiency ◽

Aerosol Particles ◽

Droplet Radius ◽

Sodium Fluorescein ◽

Extended Model ◽

Cloud Droplets ◽

Submicron Aerosol ◽

The Impact

Abstract. A new In-Cloud Aerosol Scavenging Experiment (In-CASE) has been conceived to measure the collection efficiency (CE) of submicron aerosol particles by cloud droplets. In this setup, droplets fall at their terminal velocity through a one-meter-high chamber in a laminar flow containing aerosol particles. At the bottom of the In-CASE's chamber, the droplet train is separated from the aerosol particle flow – droplets are collected in an impaction cup whereas aerosol particles are deposited on a High Efficiency Particulate Air (HEPA) filter. The collected droplets and the filter are then analysed by fluorescence spectrometry since the aerosol particles are atomised from a sodium fluorescein salt solution (C20H10Na2O5). In-CASE fully controls all the parameters which affect the CE – the droplets and aerosol particles size distributions are monodispersed, the electric charges of droplets and aerosol particles are controlled, while the relative humidity is indirectly set via the chamber's temperature. This novel In-CASE setup is presented here as well as the first measurements obtained to study the impact of relative humidity on CE. For this purpose, droplets and particles are electrically neutralised. A droplet radius of 49.6 ± 1.3 μm has been considered for six particle dry radii between 50 and 250 nm and three relative humidity levels of 71.1 ± 1.3, 82.4 ± 1.4 and 93.5 ± 0.9 %. These new CE measurements have been compared to the Wang et al. (1978) and the extended model of Dépée et al. (2019) where thermophoresis and diffusiophoresis are implemented. Both models adequately describe the relative humidity influence on the measured CE.

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Laboratory study of the collection efficiency of submicron aerosol particles by cloud droplets. Part II – Influence of electric charges

10.5194/acp-2020-832 ◽

2020 ◽

Cited By ~ 1

Author(s):

Alexis Dépée ◽

Pascal Lemaitre ◽

Thomas Gelain ◽

Marie Monier ◽

Andrea Flossmann

Keyword(s):

Relative Humidity ◽

High Efficiency ◽

Collection Efficiency ◽

Aerosol Particles ◽

Droplet Radius ◽

Sodium Fluorescein ◽

Extended Model ◽

Cloud Droplets ◽

Submicron Aerosol ◽

The Impact

Abstract. A new In-Cloud Aerosol Scavenging Experiment (In-CASE) has been developed to measure the collection efficiency (CE) of submicron aerosol particles by cloud droplets. Droplets fall at their terminal velocity through a one-meter-high chamber in a laminar flow containing aerosol particles. At the bottom of the In-CASE's chamber, the droplet train is separated from the aerosol particles flow and the droplets are collected in an impaction cup whereas aerosol particles are deposited on a High Efficiency Particulate Air (HEPA) filter. The collected droplets and the filter are then analysed by fluorescence spectrometry since the aerosol particles are atomised from a sodium fluorescein salt solution (C20H10Na2O5). In-CASE fully controls all the parameters which affect the CE – the droplets and aerosol particles size distributions are monodispersed, the electric charges of droplets and aerosol particles are known and set, while the relative humidity is indirectly controlled via the chamber's temperature. This paper details the In-CASE setup and the dataset of 70 measurements obtained to study the impact of the electric charges on CE. For this purpose, droplets and particles charges are controlled through two charging systems developed in this work – both chargers are detailed below. The droplet charge varies from −3.0 × 104 ± 1.4 × 103 to +9.6 × 104 ± 4.3 × 103 elementary charges while the particle charge ranges from the neutralisation to −90 ± 9 elementary charges depending on the particle radius. A droplet radius of 48.5 ± 1.1 μm has been considered for four particle dry radii between 100 and 250 nm. These new CE measurements have been compared to the correlation of Kraemer and Johnstone (1955) and the extended model of Dépée et al. (2019) where thermophoresis and diffusiophoresis are also considered since the measurements have been performed at a relative humidity level of 95.1 ± 0.2 %. As a result, both models adequately describe the electric charge influence on the measured CEs. Furthermore, the effect of the image charge (Jackson, 1999) in the electrostatic forces is measured.

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Droplet activation, separation, and compositional analysis: laboratory studies and atmospheric measurements

Atmospheric Measurement Techniques ◽

10.5194/amt-4-2333-2011 ◽

2011 ◽

Vol 4 (10) ◽

pp. 2333-2343 ◽

Cited By ~ 13

Author(s):

N. Hiranuma ◽

M. Kohn ◽

M. S. Pekour ◽

D. A. Nelson ◽

J. E. Shilling ◽

...

Keyword(s):

Mass Spectrometer ◽

Droplet Size ◽

Cloud Condensation Nuclei ◽

Compositional Analysis ◽

Droplet Size Distribution ◽

Polystyrene Latex ◽

Particle Analysis ◽

Laser Mass Spectrometry ◽

Atmospheric Measurements ◽

Virtual Impactor

Abstract. Droplets produced in a cloud condensation nuclei chamber (CCNC) as a function of supersaturation have been separated from unactivated aerosol particles using counterflow virtual impaction. Residual material after droplets were evaporated was chemically analyzed with an Aerodyne Aerosol Mass Spectrometer (AMS) and the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument. Experiments were initially conducted to verify activation conditions for monodisperse ammonium sulfate particles and to determine the resulting droplet size distribution as a function of supersaturation. Based on the observed droplet size, the counterflow virtual impactor cut-size was set to differentiate droplets from unactivated interstitial particles. Validation experiments were then performed to verify that only droplets with sufficient size passed through the counterflow virtual impactor for subsequent analysis. A two-component external mixture of monodisperse particles was also exposed to a supersaturation which would activate one of the types (hygroscopic salts) but not the other (polystyrene latex spheres or adipic acid). The mass spectrum observed after separation indicated only the former, validating separation of droplets from unactivated particles. Results from ambient measurements using this technique and AMS analysis were inconclusive, showing little chemical differentiation between ambient aerosol and activated droplet residuals, largely due to low signal levels. When employing as single particle mass spectrometer for compositional analysis, however, we observed enhancement of sulfate in droplet residuals.

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Mineral and biological ice-nucleating particles above the South East of the British Isles

Environmental Science: Atmospheres ◽

10.1039/d1ea00003a ◽

2021 ◽

Author(s):

Alberto Sanchez-Marroquin ◽

Jonathan S. West ◽

Ian Burke ◽

James B McQuaid ◽

Benjamin John Murray

Keyword(s):

Aerosol Particles ◽

Ice Formation ◽

British Isles ◽

The South ◽

Cloud Droplets ◽

Homogeneous Freezing

A small fraction of aerosol particles known as Ice-Nucleating Particles (INPs) have the potential to trigger ice formation in cloud droplets at higher temperatures than homogeneous freezing. INPs can strongly...

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Inside versus Outside: Ion Redistribution in Nitric Acid Reacted Sea Spray Aerosol Particles as Determined by Single Particle Analysis

Journal of the American Chemical Society ◽

10.1021/ja407117x ◽

2013 ◽

Vol 135 (39) ◽

pp. 14528-14531 ◽

Cited By ~ 73

Author(s):

Andrew P. Ault ◽

Timothy L. Guasco ◽

Olivia S. Ryder ◽

Jonas Baltrusaitis ◽

Luis A. Cuadra-Rodriguez ◽

...

Keyword(s):

Nitric Acid ◽

Single Particle ◽

Aerosol Particles ◽

Particle Analysis ◽

Sea Spray ◽

Single Particle Analysis ◽

Sea Spray Aerosol

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Rapid measurement of particle hygroscopicity and CCN activity using broad scanning supersaturation (BS2)-CCNC: calibration and intercomparison

10.5194/egusphere-egu21-8067 ◽

2021 ◽

Author(s):

Najin Kim ◽

Yafang Cheng ◽

Nan Ma ◽

Mira Pöhlker ◽

Thomas Klimach ◽

...

Keyword(s):

Particle Size ◽

Time Resolution ◽

Calibration Curve ◽

Aerosol Particles ◽

High Time ◽

Activity Measurement ◽

High Time Resolution ◽

Chemical Compositions ◽

Monotonic Relation ◽

Ccn Activity

For understanding and assessing aerosol-cloud interactions and their impact on climate, reliable measurement data of aerosol particle hygroscopicity and cloud condensation nuclei (CCN) activity are required. Furthermore, aerosol liquid water, mainly controlled by hygroscopicity, affects heterogeneous and multiphase reactions of aerosol particles. The CCN activity of aerosol particles can be determined by scanning particle size and supersaturation (S) in the CCN measurement. Compared to the existing CCN activity measurement, a broad supersaturation scanning CCN (BS2-CCN) system, in which particles are exposed to a range of S simultaneously, can measure particle hygroscopicity and CCN activity with a high-time resolution. Based on a monotonic relation between the activation supersaturation of aerosol particles (Saerosol) &#160;and the activation fraction (Fact) of the BS2-CCN measurement, we can derive &#954;, a single hygroscopicity parameter, directly.Here, we describe how the BS2-CCN system can be effectively calibrated and which factors can affect the calibration curve (Fact - Saerosol). For calibration, size-resolved CCN measurements with ammonium sulfate (AS) and sodium chloride particles are performed under the three different thermal gradient (dT) conditions (dT=6, 8, and 10). First, the shape of the calibration curve is primarily influenced by Smax, maximum S in the activation tube. We need to determine appropriate Smax depending on particle size and &#954; to be investigated. To minimize the effect of double/multiple charged particles, small&#160; Dg and &#963;g&#160; in number size distribution are recommended when generating the calibration aerosols. Sheath-to-aerosol-flow ratio (SAR) is the third factor to be considered. BS2-CCNC system uses a low SAR with a wider inlet compared to the typical CCN measurement, which can make a monotonic relation between Fact and Saerosol. Lastly, Fact is affected by particle number concentration and has a decreasing rate of 0.02/100 cm-3 (within NCN ~ 300 cm-3 for AS) due to the water consumption in the chamber. For evaluating the BS2-CCN system, inter-comparison experiments between typical DMA-CCN and BS2-CCN measurement were performed with the laboratory-generated aerosol mixture and ambient aerosols. Statistically good agreements of &#954; values between DMA-CCN and BS2-CCN measurements for both inter-comparison experiments imply that the BS2-CCN system can measure particle hygroscopicity and CCN activity well compared to the existing measurement. We expect that this new system can be applied to aircraft and ship measurements that require a high-time resolution as well as ground measurement for a broad range of hygroscopicity distribution. Because hygroscopicity is closely related to the fraction of organics/inorganics in aerosol particles, our method can also serve as a complementary approach for fast detection/estimation of aerosol chemical compositions.&#160;

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Laser ablation aerosol particle time-of-flight mass spectrometer (LAAPTOF): performance, reference spectra and classification of atmospheric samples

Atmospheric Measurement Techniques ◽

10.5194/amt-11-2325-2018 ◽

2018 ◽

Vol 11 (4) ◽

pp. 2325-2343 ◽

Cited By ~ 11

Author(s):

Xiaoli Shen ◽

Ramakrishna Ramisetty ◽

Claudia Mohr ◽

Wei Huang ◽

Thomas Leisner ◽

...

Keyword(s):

Laser Ablation ◽

Aerosol Particle ◽

Mass Spectrometer ◽

Size Range ◽

Aerosol Particles ◽

Time Of Flight ◽

Polystyrene Latex ◽

Dust Particles ◽

Data Set ◽

Flight Mass Spectrometer

Abstract. The laser ablation aerosol particle time-of-flight mass spectrometer (LAAPTOF, AeroMegt GmbH) is able to identify the chemical composition and mixing state of individual aerosol particles, and thus is a tool for elucidating their impacts on human health, visibility, ecosystem, and climate. The overall detection efficiency (ODE) of the instrument we use was determined to range from ∼  (0.01 ± 0.01) to ∼  (4.23 ± 2.36) % for polystyrene latex (PSL) in the size range of 200 to 2000 nm, ∼  (0.44 ± 0.19) to ∼  (6.57 ± 2.38) % for ammonium nitrate (NH4NO3), and ∼  (0.14 ± 0.02) to ∼  (1.46 ± 0.08) % for sodium chloride (NaCl) particles in the size range of 300 to 1000 nm. Reference mass spectra of 32 different particle types relevant for atmospheric aerosol (e.g. pure compounds NH4NO3, K2SO4, NaCl, oxalic acid, pinic acid, and pinonic acid; internal mixtures of e.g. salts, secondary organic aerosol, and metallic core–organic shell particles; more complex particles such as soot and dust particles) were determined. Our results show that internally mixed aerosol particles can result in spectra with new clusters of ions, rather than simply a combination of the spectra from the single components. An exemplary 1-day ambient data set was analysed by both classical fuzzy clustering and a reference-spectra-based classification method. Resulting identified particle types were generally well correlated. We show how a combination of both methods can greatly improve the interpretation of single-particle data in field measurements.

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