scholarly journals Scanning supersaturation condensation particle counter applied as a nano-CCN counter for size-resolved analysis of the hygroscopicity and chemical composition of nanoparticles

2015 ◽  
Vol 8 (5) ◽  
pp. 2161-2172 ◽  
Author(s):  
Z. Wang ◽  
H. Su ◽  
X. Wang ◽  
N. Ma ◽  
A. Wiedensohler ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Ammonium Sulfate ◽  
Inorganic Compounds ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Counting Efficiency ◽  
Particle Counter ◽  
Working Fluids ◽  
Condensation Particle Counter ◽  
Abstract Knowledge

Abstract. Knowledge about the chemical composition of aerosol particles is essential to understand their formation and evolution in the atmosphere. Due to analytical limitations, however, relatively little information is available for sub-10 nm particles. We present the design of a nano-cloud condensation nuclei counter (nano-CCNC) for measuring size-resolved hygroscopicity and inferring chemical composition of sub-10 nm aerosol particles. We extend the use of counting efficiency spectra from a water-based condensation particle counter (CPC) and link it to the analysis of CCN activation spectra, which provides a theoretical basis for the application of a scanning supersaturation CPC (SS-CPC) as a nano-CCNC. Measurement procedures and data analysis methods are demonstrated through laboratory experiments with monodisperse particles of diameter down to 2.5 nm, where sodium chloride, ammonium sulfate, sucrose and tungsten oxide can be easily discriminated by different characteristic supersaturations of water droplet formation. A near-linear relationship between hygroscopicity parameter κ and organic mass fraction is also found for sucrose-ammonium sulfate mixtures. The design is not limited to the water CPC, but also applies to CPCs with other working fluids (e.g. butanol, perfluorotributylamine). We suggest that a combination of SS-CPCs with multiple working fluids may provide further insight into the chemical composition of nanoparticles and the role of organic and inorganic compounds in the initial steps of atmospheric new particle formation and growth.

scholarly journals Scanning supersaturation CPC applied as a nano-CCN counter for size-resolved analysis of the hygroscopicity and chemical composition of nanoparticles

2014 ◽  
Vol 7 (11) ◽  
pp. 11137-11168
Author(s):  
Z. B. Wang ◽  
H. Su ◽  
X. Wang ◽  
N. Ma ◽  
A. Wiedensohler ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Inorganic Compounds ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Counting Efficiency ◽  
Working Fluids ◽  
Condensation Particle Counter ◽  
Formation And Evolution ◽  
Insight Into

Abstract. Chemical composition is essential for understanding the formation and evolution of atmospheric aerosol particles. Due to analytical limitations, however, relatively little information is available for sub-10 nm particles. We present the design of a nano-cloud condensation nuclei counter (nano-CCNC) for measuring size-resolved hygroscopicity and inferring chemical composition of sub-10 nm aerosol particles. We extend the use of counting efficiency spectra from a water-based condensation particle counter (CPC) and link it to the analysis of CCN activation spectra, which provides a theoretical basis for the application of a scanning supersaturation CPC (SS-CPC) as a nano-CCNC. Measurement procedures and data analysis methods are demonstrated through laboratory experiments with monodisperse particles of diameter down to 2.5 nm, where sodium chloride, ammonium sulfate, sucrose and tungsten oxide can be easily discriminated by different characteristic supersaturations of water droplet formation. The design is not limited to the water CPC, but also applies to CPCs with other working fluids (e.g. butanol, perfluorotributylamine). We suggest that a combination of SS-CPCs with multiple working fluids may provide further insight into the chemical composition of nanoparticles and the role of organic and inorganic compounds in the initial steps of atmospheric new particle formation and growth.

scholarly journals Effects of SO<sub>2</sub> oxidation on ambient aerosol growth in water and ethanol vapours

2005 ◽  
Vol 5 (3) ◽  
pp. 767-779 ◽  
Author(s):  
T. Petäjä ◽  
V.-M. Kerminen ◽  
K. Hämeri ◽  
P. Vaattovaara ◽  
J. Joutsensaari ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Sulphuric Acid ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
The Arctic ◽  
Ambient Conditions ◽  
Similar Chemical ◽  
Ethanol Vapours ◽  
Hygroscopic Particles ◽  
Ultrafine Aerosol

Abstract. Hygroscopicity (i.e. water vapour affinity) of atmospheric aerosol particles is one of the key factors in defining their impacts on climate. Condensation of sulphuric acid onto less hygroscopic particles is expected to increase their hygrocopicity and hence their cloud condensation nuclei formation potential. In this study, differences in the hygroscopic and ethanol uptake properties of ultrafine aerosol particles in the Arctic air masses with a different exposure to anthropogenic sulfur pollution were examined. The main discovery was that Aitken mode particles having been exposed to polluted air were more hygroscopic and less soluble to ethanol than after transport in clean air. This aging process was attributed to sulphur dioxide oxidation and subsequent condensation during the transport of these particle to our measurement site. The hygroscopicity of nucleation mode aerosol particles, on the other hand, was approximately the same in all the cases, being indicative of a relatively similar chemical composition despite the differences in air mass transport routes. These particles had also been produced closer to the observation site typically 3–8 h prior to sampling. Apparently, these particles did not have an opportunity to accumulate sulphuric acid on their way to the site, but instead their chemical composition (hygroscopicity and ethanol solubility) resembled that of particles produced in the local or semi-regional ambient conditions.

scholarly journals Cloud activation properties of aerosol particles in a continental Central European urban environment

2021 ◽  
Vol 21 (14) ◽  
pp. 11289-11302
Author(s):  
Imre Salma ◽  
Wanda Thén ◽  
Máté Vörösmarty ◽  
András Zénó Gyöngyösi
Keyword(s):  
Chemical Composition ◽  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Number Concentration ◽  
Urban Aerosol ◽  
Condensation Nuclei ◽  
Frequency Distributions ◽  
Remote Locations ◽  
Cloud Activation

Abstract. Collocated measurements using a condensation particle counter, differential mobility particle sizer and cloud condensation nuclei counter were realised in parallel in central Budapest from 15 April 2019 to 14 April 2020 to gain insight into the cloud activation properties of urban aerosol particles. The median total particle number concentration was 10.1 × 103 cm−3. The median concentrations of cloud condensation nuclei (CCN) at water vapour supersaturation (S) values of 0.1 %, 0.2 %, 0.3 %, 0.5 % and 1.0 % were 0.59, 1.09, 1.39, 1.80 and 2.5 × 103 cm−3, respectively. The CCN concentrations represented 7–27 % of all particles. The CCN concentrations were considerably larger but the activation fractions were systematically substantially smaller than observed in regional or remote locations. The effective critical dry particle diameters (dc,eff) were derived utilising the CCN concentrations and particle number size distributions. Their median values at the five supersaturation values considered were 207, 149, 126, 105 and 80 nm, respectively; all of these diameters were positioned within the accumulation mode of the typical particle number size distribution. Their frequency distributions revealed a single peak for which the geometric standard deviation increased monotonically with S. This broadening indicated high time variability in the activating properties of smaller particles. The frequency distributions also showed fine structure, with several compositional elements that seemed to reveal a consistent or monotonical tendency with S. The relationships between the critical S and dc,eff suggest that urban aerosol particles in Budapest with diameters larger than approximately 130 nm showed similar hydroscopicity to corresponding continental aerosol particles, whereas smaller particles in Budapest were less hygroscopic than corresponding continental aerosol particles. Only modest seasonal cycling in CCN concentrations and activation fractions was seen, and only for large S values. This cycling likely reflects changes in the number concentration, chemical composition and mixing state of the particles. The seasonal dependencies of dc,eff were featureless, indicating that the droplet activation properties of the urban particles remained more or less the same throughout the year. This is again different from what is seen in non-urban locations. Hygroscopicity parameters (κ values) were computed without determining the time-dependent chemical composition of the particles. The median values for κ were 0.15, 0.10, 0.07, 0.04 and 0.02, respectively, at the five supersaturation values considered. The averages suggested that the larger particles were considerably more hygroscopic than the smaller particles. We found that the κ values for the urban aerosol were substantially smaller than those previously reported for aerosols in regional or remote locations. All of these characteristics can be linked to the specific source composition of particles in cities. The relatively large variability in the hygroscopicity parameters for a given S emphasises that the individual values represent the CCN population in ambient air while the average hygroscopicity parameter mainly corresponds to particles with sizes close to the effective critical dry particle diameter.

Counting efficiency measurements for a new condensation particle counter

2014 ◽  
Vol 70 ◽  
pp. 11-14 ◽  
Author(s):  
S. Baltzer ◽  
S. Onel ◽  
M. Weiss ◽  
M. Seipenbusch
Keyword(s):  
Counting Efficiency ◽  
Particle Counter ◽  
Condensation Particle Counter

scholarly journals Hygroscopic behavior and chemical composition evolution of internally mixed aerosols composed of oxalic acid and ammonium sulfate

2017 ◽  
Vol 17 (20) ◽  
pp. 12797-12812 ◽  
Author(s):  
Xiaowei Wang ◽  
Bo Jing ◽  
Fang Tan ◽  
Jiabi Ma ◽  
Yunhong Zhang ◽  
...  
Keyword(s):  
Growth Factors ◽  
Chemical Composition ◽  
Relative Humidity ◽  
Oxalic Acid ◽  
Ammonium Sulfate ◽  
Water Uptake ◽  
Aerosol Particles ◽  
Atmospheric Environment ◽  
Dehydration Process ◽  
Ammonium Hydrogen

Abstract. Although water uptake of aerosol particles plays an important role in the atmospheric environment, the effects of interactions between components on chemical composition and hygroscopicity of particles are still not well constrained. The hygroscopic properties and phase transformation of oxalic acid (OA) and mixed particles composed of ammonium sulfate (AS) and OA with different organic to inorganic molar ratios (OIRs) have been investigated by using confocal Raman spectroscopy. It is found that OA droplets first crystallize to form OA dihydrate at 71 % relative humidity (RH), and further lose crystalline water to convert into anhydrous OA around 5 % RH during the dehydration process. The deliquescence and efflorescence point for AS is determined to be 80.1 ± 1.5 % RH and 44.3 ± 2.5 % RH, respectively. The observed efflorescence relative humidity (ERH) for mixed OA ∕ AS droplets with OIRs of 1 : 3, 1 : 1 and 3 : 1 is 34.4 ± 2.0, 44.3 ± 2.5 and 64.4 ± 3.0 % RH, respectively, indicating the elevated OA content appears to favor the crystallization of mixed systems at higher RH. However, the deliquescence relative humidity (DRH) of AS in mixed OA ∕ AS particles with OIRs of 1 : 3 and 1 : 1 is observed to occur at 81.1 ± 1.5 and 77 ± 1.0 % RH, respectively. The Raman spectra of mixed OA ∕ AS droplets indicate the formation of ammonium hydrogen oxalate (NH4HC2O4) and ammonium hydrogen sulfate (NH4HSO4) from interactions between OA and AS in aerosols during the dehydration process on the time scale of hours, which considerably influence the subsequent deliquescence behavior of internally mixed particles with different OIRs. The mixed OA ∕ AS particles with an OIR of 3 : 1 exhibit no deliquescence transition over the RH range studied due to the considerable transformation of (NH4)2SO4 into NH4HC2O4 with a high DRH. Although the hygroscopic growth of mixed OA ∕ AS droplets is comparable to that of AS or OA at high RH during the dehydration process, Raman growth factors of mixed particles after deliquescence are substantially lower than those of mixed OA ∕ AS droplets during the efflorescence process and further decrease with elevated OA content. The discrepancies for Raman growth factors of mixed OA ∕ AS particles between the dehydration and hydration process at high RH can be attributed to the significant formation of NH4HC2O4 and residual OA, which remain solid at high RH and thus result in less water uptake of mixed particles. These findings improve the understanding of the role of reactions between dicarboxylic acid and inorganic salt in the chemical and physical properties of aerosol particles, and might have important implications for atmospheric chemistry.

scholarly journals Simulation-aided characterization of a versatile water condensation particle counter for atmospheric airborne research

2021 ◽  
Author(s):  
Fan Mei ◽  
Steven Spielman ◽  
Susanne Hering ◽  
Jian Wang ◽  
Mikhail Pekour ◽  
...  
Keyword(s):  
Atmospheric Aerosols ◽  
Health And Safety ◽  
Low Pressure ◽  
Counting Efficiency ◽  
Droplet Growth ◽  
Particle Counter ◽  
Condensation Particle Counter ◽  
Airborne Measurements ◽  
Horizontal Variations

Abstract. Capturing the vertical profiles and horizontal variations of atmospheric aerosols often requires accurate airborne measurements. With the advantage of avoiding health and safety concerns related to the use of butanol or other chemicals, a water-based condensation particle counter (wCPC) has emerged to provide measurements under various environments. However, the airborne deployment of wCPC is relatively rare due to the lack of characterization of wCPC performance. This study investigates the performance of a commercial "versatile" water CPC (vWCPC Model 3789, TSI) under low-pressure conditions. The effect of conditioner temperature on wCPC performance at low pressure is examined through numerical simulation and laboratory experiments. We show that the default instrument temperature setting of 30 °C for the conditioner is not suitable for airborne measurement and that the optimal conditioner temperature for low-pressure operation is 27 °C. Additionally, we show that insufficient droplet growth becomes more significant under the low-pressure operation. The variation in the chemical composition can contribute up to 20 % uncertainty in the counting efficiency of the wCPC, but this variation is independent of pressure.

scholarly journals Instrument Artifacts Lead to Uncertainties in Parameterizations of Cloud Condensation Nucleation

2018 ◽  
Author(s):  
Jessica A. Mirrielees ◽  
Sarah D. Brooks
Keyword(s):  
Climate Models ◽  
Cloud Condensation Nuclei ◽  
Counting Efficiency ◽  
Operating Conditions ◽  
High Concentration ◽  
Sheath Flow ◽  
Condensation Particle Counter ◽  
Cloud Properties ◽  
Climate Forcings ◽  
High Concentrations

Abstract. The concentrations of cloud condensation nuclei (CCN) modulate cloud properties, rainfall location and intensity, and climate forcings. This work assesses uncertainties in CCN measurements and the apparent hygroscopicity parameter (κapp) which is widely used to represent CCN populations in climate models. CCN measurements require accurate operation of three instruments: the CCN instrument, the differential mobility analyzer (DMA), and the condensation particle counter (CPC). Assessment of DMA operation showed that varying the ratio of aerosol to sheath flow from 0.05 to 0.30 resulted in discrepancies between the κapp values calculated from CCN measurements and the literature value. Discrepancies were found to increase from effectively zero to 0.18 for sodium chloride, and from effectively zero to 0.08 for ammonium sulfate. The ratio of excess to sheath flow was also varied, which shifted the downstream aerosol distribution towards smaller particle diameters (for excess flow < sheath flow) or larger particle diameters (for excess flow > sheath flow) than predicted. For the CPC instrument, undercounting occurred at high concentrations, resulting in calculated κapp lower than the literature values. Lastly, undercounting by CCN instruments at high concentration was also assessed, taking the effect of supersaturation on counting efficiency into account. Under recommended operating conditions, the combined DMA, CPC, and CCN uncertainties in κapp are 1.1 % or less for 25 to 200 nm diameter aerosols.

scholarly journals Calibration and evaluation of broad supersaturation scanning (BS2) cloud condensation nuclei counter for rapid measurement of particle hygroscopicity and CCN activity

2021 ◽  
Author(s):  
Najin Kim ◽  
Yafang Cheng ◽  
Nan Ma ◽  
Mira L. Pöhlker ◽  
Thomas Klimach ◽  
...  
Keyword(s):  
Particle Size ◽  
Chemical Composition ◽  
Time Resolution ◽  
Calibration Curve ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
High Time ◽  
Activity Measurement ◽  
High Time Resolution ◽  
Ccn Activity

Abstract. 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. The CCN activity of aerosol particles can be determined by scanning particle size and supersaturation (S) in CCN measurements. Compared to the existing differential mobility analyzer (DMA)-CCN activity measurement, a broad supersaturation scanning CCN (BS2-CCN) system, in which particles are exposed to a range of S simultaneously, can measure the CCN activity with a high time-resolution. Based on a monotonic relation between the activation supersaturation of aerosol particles (Saerosol) and the activated fraction (Fact) of the BS2-CCN measurement, we can derive κ, 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 and sodium chloride particles are performed under the three different thermal gradient (dT) conditions (dT = 6, 8, and 10 K). We point out key processes that can affect the calibration curve and thereby need to be considered as follows: First, the shape of the calibration curve is primarily influenced by Smax, the maximum S in the activation tube. We need to determine appropriate Smax depending on particle size and κ to be investigated. To minimize the effect of multiply charged particles, small geometric mean diameter (𝐷𝑔) and 𝜎𝑔 geometric standard deviation (𝜎𝑔) in number size distribution are recommended when generating the calibration aerosols. Last, Fact is affected by particle number concentration and has a decreasing rate of 0.02/100 cm−3 due to the water consumption in the activation tube. 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. Good agreements of κ values between DMA-CCN and BS2-CCN measurements for both experiments show that the BS2-CCN system can measure CCN activity well compared to the existing measurement, and can measure a broad range of hygroscopicity distribution with a high time-resolution (~1 second vs. few minutes for a standard CCN activity measurement). As the hygroscopicity can be used as a proxy for the chemical composition, our method can also serve as a complementary approach for fast and size-resolved detection/estimation of aerosol chemical composition.

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