The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Markku Kulmala - One of the best experts on this subject based on the ideXlab platform.
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the high charge fraction of flame generated Particles in the size range below 3 nm measured by enhanced Particle detectors
Combustion and Flame, 2017Co-Authors: Yang Wang, Juha Kangasluoma, Michel Attoui, Markku Kulmala, Tuukka Petaja, Heikki Junninen, Jiaxi Fang, Pratim BiswasAbstract:Abstract Charging in flames significantly affects the properties of the resultant Particles produced because of its influence in almost all stages of Particle formation. The charging characteristics of flame-generated sub-3 nm Particles were investigated with three enhanced Particle detectors including a high resolution differential mobility analyzer (DMA) coupled with an electrometer, a Particle size magnifier coupled with a butanol-based Condensation Particle Counter (PSM-bCPC), and an atmospheric pressure interface time-of-flight mass spectrometer (APi-TOF). Up to 95% of the flame-generated sub-3 nm Particles were charged at a sampling height of 5 mm above the burner, indicating the existence of a strong ionization process in the investigated flame. This high fraction of charged Particles contradicts the classical charging theories, which predict
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remarks on ion generation for cpc detection efficiency studies in sub 3 nm size range
Aerosol Science and Technology, 2013Co-Authors: Juha Kangasluoma, Joona Mikkilä, Katrianne Lehtipalo, Michel Attoui, Mikko Sipila, Markku Kulmala, Heikki Junninen, Joonas Vanhanen, D R Worsnop, Tuukka PetajaAbstract:To calibrate a newly developed Condensation Particle Counter, samples of known chemical composition are needed as the chemistry plays a role in the activation process. For that, we have built a calibration setup and produced ammonium sulfate, sodium chloride, tungsten oxide, silver, alkyl halide, and ionic liquid clusters down to 1 nm in mobility diameter in positive and negative mode. The chemical composition of most negatively charged clusters was solved using high-resolution mass spectrometer and we identified about 70% of the total signal of the mass spectrometer. For the Airmodus Particle Size Magnifier, which was the instrument to be calibrated, we measured cutoff diameters of 1.1, 1.3, 1.4, 1.6, and 1.6–1.8 nm for negative sodium chloride, ammonium sulfate, tungsten oxide, silver, and positive organics, respectively. From the alkyl halide and ionic liquid experiments, we concluded that the composition plays a bigger role than the charge state of the cluster in the activation process. We also showed...
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applying the Condensation Particle Counter battery cpcb to study the water affinity of freshly formed 2 9 nm Particles in boreal forest
Atmospheric Chemistry and Physics, 2009Co-Authors: Ilona Riipinen, Mikko Sipila, Tuukka Petaja, Hanna E Manninen, Taina Ylijuuti, Michael Boy, Mikael Ehn, Heikki Junninen, Markku KulmalaAbstract:Abstract. Measurements on the composition of nanometer-sized atmospheric Particles are the key to understand which vapors participate in the secondary aerosol formation processes. Knowledge on these processes is crucial in assessing the climatic effects of secondary aerosol formation. We present data of >2 nm Particle concentrations and their water-affinity measured with the Condensation Particle Counter Battery (CPCB) at a boreal forest site in Hyytiala, Finland, during spring 2006. The data reveal that during new Particle formation events, the smallest Particles activate for growth at clearly smaller sizes in water than in butanol vapor. However, even at 2–4 nm, there are days when the Particles seem to be less hygroscopic than ammonium sulfate or sulfuric acid, which are often referred to as the most likely compounds present in atmospheric nucleation. This observation points to the possible presence of water-soluble organics, even at the very first steps on Particle formation. The water-affinity of the Particles decreases with size, indicating that the vapors that participate in the first steps of the Particle formation and growth are more hygroscopic than the vapors contributing to the later stages of the growth. This suggests that the relative role of less hygroscopic organics in atmospheric Particle growth increases as a function of Particle size.
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nanometer Particle detection by the Condensation Particle Counter uf 02proto
Aerosol Science and Technology, 2008Co-Authors: Genrik Mordas, Mikko Sipila, Markku KulmalaAbstract:In this study we present a method for how to improve the Particle detection efficiency of Condensation Particle Counters. The recently developed swirling flow Condensation Particle Counter UF-02proto was studied. Investigations show that at default regime (when the temperature difference between the saturator and the condenser is 32.5°C) an instrument background is 0.002 cm−3, a maximum measurable number concentration is 100000 cm−3, and an instrument cut-size D50 is 4.4 nm. Increasing the temperature difference, the homogeneous nucleation starts around the temperature difference of 39.0°C. Subsequent temperature difference increasing enhances the number concentration of the nucleated Particles. However, the experimental results show that the nucleation process can be prevented using existing aerosol Particles in the supersaturated region. For example, when the number concentration of 15 nm silver Particles exceeds 4000 cm−3 then the homogeneous nucleation inside CPC disappears. The detection efficiency w...
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the Condensation Particle Counter battery cpcb a new tool to investigate the activation properties of nanoParticles
Journal of Aerosol Science, 2007Co-Authors: Markku Kulmala, Genrik Mordas, Mikko Sipila, Tuukka Petaja, Pasi Aalto, Tiia Gronholm, Hanna Vehkamaki, Anca I Hienola, Erik Herrmann, Ilona RiipinenAbstract:The formation and growth of fresh atmospheric aerosol Particles was investigated using a Condensation Particle Counter battery (CPCB). This instrument is a matrix of four separate CPCs, which differ in the combination of both cut-off size and working liquid (water; n-butanol). In a first step, the CPC counting efficiencies and cut-off sizes were carefully characterised under laboratory conditions for different condensing vapours, temperature differences between condenser and saturator, and test aerosol types. In addition, the activation process was described theoretically, and modelled numerically for the given CPC configurations. These results confirmed that water-soluble and water-insoluble as well as butanol-soluble and butanol-insoluble aerosol Particles may be discriminated in the CPCB through different activation diameters. Therefore, the CPCB represents a novel tool to infer information on the chemical composition of aerosol Particles between 2 and 20 nm. To test the applicability of the CPCB under field conditions, the CPCB was operated at a rural background station in Finland (Hyytiala) in April and May 2005. The results indicate that growing nucleation mode Particles were water-soluble both at 3 and 11 nm.
Kaarle Hameri - One of the best experts on this subject based on the ideXlab platform.
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notably improved inversion of differential mobility Particle sizer data obtained under conditions of fluctuating Particle number concentrations
Atmospheric Measurement Techniques, 2016Co-Authors: Bjarke Molgaard, Jarno Vanhatalo, P P Aalto, Nonne L Prisle, Kaarle HameriAbstract:Abstract. The differential mobility Particle sizer (DMPS) is designed for measurements of Particle number size distributions. It performs a number of measurements while scanning over different Particle sizes. A standard assumption in the data-processing (inversion) algorithm is that the size distribution remains the same throughout each scan. For a DMPS deployed in an urban area this assumption is likely to be violated most of the time, and the resulting size distribution data are unreliable. To improve the reliability, we developed a new algorithm using a statistical model in which the problematic assumption was replaced with more realistic smoothness assumptions, which were expressed through Gaussian process prior probabilities. We tested the model with data from a twin DMPS located at an urban background site in Helsinki and found that it provides size distribution data which are much more realistic. Furthermore, Particle number concentrations extracted from the DMPS data were compared with data from a Condensation Particle Counter. At 10 min resolution, the correlation for a period of 10 days was 0.984 with the new algorithm and 0.967 with the old one. Moreover, the time resolution was improved, and at 30 s resolution we obtained positive correlations for 89 % of the scans. Thus, the quality of the inverted data was clearly improved.
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detection efficiency of a water based tsi Condensation Particle Counter 3785
Aerosol Science and Technology, 2006Co-Authors: Tuukka Petaja, Genrik Mordas, Hanna E Manninen, Pasi Aalto, Kaarle Hameri, Markku KulmalaAbstract:In this article we present observations on the detection efficiency of a recently developed TSI 3785 Water Condensation Particle Counter (WCPC). The instrument relies on activation of sampled Particles by water Condensation. The supersaturation is generated by directing a saturated airflow into a “growth tube,” in which the mass transfer of water vapor is faster than heat transfer. This results in supersaturated conditions with respect to water vapor in the centerline of a “growth tube.” In this study, the cut-off diameter, that is, the size, where 50% of the sampled Particles are successfully activated, varied from 4 to 14 nm for silver Particles as a function of temperature difference between the saturator and the growth tube. The solubility of the sampled Particles to water played an important role in the detection efficiency. Cut-off diameters for ammonium sulphate and sodium chloride Particles were 5.1 and 3.6–3.8 nm, respectively at nominal operation conditions. Corresponding cut-off diameter for hy...
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aerosol Particle number concentration measurements in five european cities using tsi 3022 Condensation Particle Counter over a three year period during health effects of air pollution on susceptible subpopulations
Journal of The Air & Waste Management Association, 2005Co-Authors: Pasi Aalto, Markku Kulmala, Kaarle Hameri, Pentti Paatero, Tom Bellander, Niklas Berglind, Laura Bouso, Gemma Castanovinyals, Jordi Sunyer, Giorgio CattaniAbstract:Abstract In this study, long-term aerosol Particle total number concentration measurements in five metropolitan areas across Europe are presented. The measurements have been carried out in Augsburg, Barcelona, Helsinki, Rome, and Stockholm using the same instrument, a Condensation Particle Counter (TSI model 3022). The results show that in all of the studied cities, the winter concentrations are higher than the summer concentrations. In Helsinki and in Stockholm, winter concentrations are higher by a factor of two and in Augsburg almost by a factor of three compared with summer months. The winter maximum of the monthly average concentrations in these cities is between 10,000 cm-3 and 20,000 cm-3, whereas the summer min is ˜;5000–6000 cm-3. In Rome and in Barcelona, the winters are more polluted compared with summers by as much as a factor of 4–10. The winter maximum in both Rome and Barcelona is close to 100,000 cm-3, whereas the summer minimum is >10,000 cm-3. During the weekdays the maximum of the hourl...
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aerosol Particle number concentration measurements in five european cities using tsi 3022 Condensation Particle Counter over a three year period during health effects of air pollution on susceptible subpopulations
Journal of The Air & Waste Management Association, 2005Co-Authors: Pasi Aalto, Markku Kulmala, Kaarle Hameri, Pentti Paatero, Tom Bellander, Niklas Berglind, Laura Bouso, Gemma Castanovinyals, Jordi Sunyer, Giorgio CattaniAbstract:In this study, long-term aerosol Particle total number concentration measurements in five metropolitan areas across Europe are presented. The measurements have been carried out in Augsburg, Barcelona, Helsinki, Rome, and Stockholm using the same instrument, a Condensation Particle Counter (TSI model 3022). The results show that in all of the studied cities, the winter concentrations are higher than the summer concentrations. In Helsinki and in Stockholm, winter concentrations are higher by a factor of two and in Augsburg almost by a factor of three compared with summer months. The winter maximum of the monthly average concentrations in these cities is between 10,000 cm(-3) and 20,000 cm(-3), whereas the summer min is approximately 5000-6000 cm(-3). In Rome and in Barcelona, the winters are more polluted compared with summers by as much as a factor of 4-10. The winter maximum in both Rome and Barcelona is close to 100,000 cm(-3), whereas the summer minimum is > 10,000 cm(-3). During the weekdays the maximum of the hourly average concentrations in all of the cities is detected during the morning hours between 7 and 10 a.m. The evening maxima were present in Barcelona, Rome, and Augsburg, but these were not as pronounced as the morning ones. The daily maxima in Helsinki and Stockholm are close or even lower than the daily minima in the more polluted cities. The concentrations between these two groups of cities are different with a factor of about five during the whole day. The study pointed out the influence of the selection of the measurement site and the configuration of the sampling line on the observed concentrations.
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design and performance characteristics of a Condensation Particle Counter uf 02proto
Boreal Environment Research, 2005Co-Authors: Genrik Mordas, Markku Kulmala, Tuukka Petaja, Pasi Aalto, Vytautas Matulevicius, Vytautas Grigoraitis, Vidmantas Ulevicius, Vaclovas Grauslys, Ari Ukkonen, Kaarle HameriAbstract:In this paper we present a design of a new swirling flow Condensation Particle Counter UF-02proto, which has a continuous sampling flow. The performance and characteristics of the instrument were investigated. We studied experimentally the concentration range of the instrument and the detection efficiency as a function of Particle diameter for silver.Particles. The lower cut-off size of the CPC, i.e. the limiting size when 50% of the Particles are successfully accounted for, was determined to be 4.35-4.46 nm, depending slightly on a form of a fitted exponential step-function. The counting efficiency of the CPC at high Particle concentrations was experimentally investigated using 20 nm silver Particles. The maximum observable number concentration with a single Particle counting method was approximately 100 000 cm -3 with an accuracy of 20%. The operation of the CPC UF-02proto was also compared with that of a commercially available CPC when operating both instruments in parallel. The CPC proved to be suitable for a variety of applications with a wide range of Particle concentrations and Particle sizes.
Peter H Mcmurry - One of the best experts on this subject based on the ideXlab platform.
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acid base chemical reaction model for nucleation rates in the polluted atmospheric boundary layer
19th International Conference on Nucleation and Atmospheric Aerosols ICNAA 2013, 2013Co-Authors: Modi Chen, Mari Titcombe, Jingkun Jiang, Chongai Kuang, M L Fischer, F L Eisele, Ilja J Siepmann, David R Hanson, Jun Zhao, Peter H McmurryAbstract:Measurements of aerosol number distributions down to one molecule have provided information that we’ve used to develop a new approach for modeling atmospheric nucleation rates. Measurements were carried out with the Cluster Chemical Ionization Mass Spectrometer (Cluster CIMS), the scanning mobility spectrometer using a diethylene glycol Condensation Particle Counter as detector (DEG SMPS), and an ambient pressure proton transfer mass spectrometer for ammonia and amines (AmPMS). The model explains nucleation as a result of cluster evolution due to a sequence of acid-base reactions. We conclude that the smallest stable cluster contains four sulfuric acid molecules. The model leads to a simple analytic expression for nucleation rates that is reasonably consistent (i.e., ± 10x) with atmospheric observations. The model predicts that nucleation rates are equal to a prefactor, P<1, times the sulfuric acid vapor collision rate, (i.e., J=P⋅0.5⋅k11 *[H2SO4]2).
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sulfuric acid nucleation power dependencies variation with relative humidity and effect of bases
Atmospheric Chemistry and Physics, 2012Co-Authors: J H Zollner, Peter H Mcmurry, W A Glasoe, B Panta, K K Carlson, D R HansonAbstract:Abstract. Nucleation of Particles composed of sulfuric acid, water, and nitrogen base molecules was studied using a continuous flow reactor. The Particles formed from these vapors were detected with an ultrafine Condensation Particle Counter, while vapors of sulfuric acid and nitrogen bases were detected by chemical ionization mass spectrometry. Variation of Particle numbers with sulfuric acid concentration yielded a power dependency on sulfuric acid of 5 ± 1 for relative humidities of 14–68% at 296 K; similar experiments with varying water content yielded power dependencies on H 2 O of ~7. The critical cluster contains about 5 H 2 SO 4 molecules and a new treatment of the power dependency for H 2 O suggests about 12 H 2 O molecules for these conditions. Addition of 2-to-45 pptv of ammonia or methyl amine resulted in up to millions of times more Particles than in the absence of these compounds. Particle detection capabilities, sulfuric acid and nitrogen base detection, wall losses, and the extent of Particle growth are discussed. Results are compared to previous laboratory nucleation studies and they are also discussed in terms of atmospheric nucleation scenarios.
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electrical mobility spectrometer using a diethylene glycol Condensation Particle Counter for measurement of aerosol size distributions down to 1 nm
Aerosol Science and Technology, 2011Co-Authors: Modi Chen, Jingkun Jiang, Chongai Kuang, Michel Attoui, Peter H McmurryAbstract:We report a new scanning mobility Particle spectrometer (SMPS) for measuring number size distributions of Particles down to ∼1 nm mobility diameter. This SMPS includes an aerosol charger, a TSI 3085 nano differential mobility analyzer (nanoDMA), an ultrafine Condensation Particle Counter (UCPC) using diethylene glycol (DEG) as the working fluid, and a conventional butanol CPC (the “booster”) to detect the small droplets leaving the DEG UCPC. The response of the DEG UCPC to negatively charged sodium chloride Particles with mobility diameters ranging from 1–6 nm was measured. The sensitivity of the DEG UCPC to Particle composition was also studied by comparing its response to positively charged 1.47 and 1.70 nm tetra-alkyl ammonium ions, sodium chloride, and silver Particles. A high resolution differential mobility analyzer was used to generate the test Particles. These results show that the response of this UCPC to sub-2 nm Particles is sensitive to Particle composition. The applicability of the new SMPS f...
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effect of working fluid on sub 2 nm Particle detection with a laminar flow ultrafine Condensation Particle Counter
Aerosol Science and Technology, 2009Co-Authors: Kenjiro Iida, Mark R Stolzenburg, Peter H McmurryAbstract:The effect of working fluid on size-dependent activation efficiencies with the laminar flow ultrafine Condensation Particle Counter described by Stolzenburg and McMurry (1991) was studied theoretically and experimentally. Criteria considered include tendency to avoid homogeneous nucleation within the condenser and toxicity. The working fluids that were identified have vapor pressures below that of butanol, so Particles grow to smaller sizes and are more difficult to detect optically. Therefore we use a second, conventional CPC as a “booster” to grow Particles to a detectable size. Experiments were performed to obtain the size- and material-dependent activation efficiencies for ethylene glycol, diethylene glycol, propylene glycol, oleic acid, and DOS. Using diethylene glycol and oleic acid, values of the 50% activation efficiency diameter, Dp50 , for negatively charged Particles generated by evaporating sodium chloride, ammonium sulfate, and silver were < 1.2 (< 0.8) nm, 1.4–1.5 (1.0–1.2) nm, and 1.9–2.0 (...
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an ultrafine water based Condensation Particle Counter and its evaluation under field conditions
Aerosol Science and Technology, 2008Co-Authors: Kenjiro Iida, Peter H Mcmurry, Gregory S Lewis, Arantzazu Eigurenfernandez, Mark R Stolzenburg, Frederick R Quant, Derek R Oberreit, Patricia B Keady, James N Smith, Nathan M KreisbergAbstract:An ultrafine, water-based Condensation Particle Counter (U-WCPC, TSI Model 3786) has been compared to a butanol-based ultrafine Counter (U-BCPC, TSI Model 3025) for measurement of atmospheric and freeway-tunnel aerosols. The U-WCPC utilizes a warm, wet-walled growth tube to activate and grow Particles through water Condensation in a laminar-flow. It has an aerosol sampling rate of 0.3 L/min, and a nominal detection limit near 3 nm. Several field comparisons were made to the butanol-based instrument with the same nominal detection limit. For measurements of size-selected aerosols with diameters of 5 nm and larger the two instruments generally agreed, with a mean response within 5%. At 3 nm Particle size differences were observed, and these differences varied with the data set. Measurements of ambient aerosol in Boulder, Colorado showed higher counting efficiency at 3 nm with the U-BCPC, while in a California freeway tunnel the opposite trend was observed, with higher counting efficiencies at 3 nm observed ...
Michel Attoui - One of the best experts on this subject based on the ideXlab platform.
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optimizing the activation efficiency of sub 3 nm Particles in a laminar flow Condensation Particle Counter model simulation
Journal of Aerosol Science, 2021Co-Authors: Weixing Hao, Michel Attoui, Jiaoshi Zhang, Mark R Stolzenburg, Yang WangAbstract:Abstract The measurement of airborne Particles with sizes below 3 nm is critical, as it helps the understanding of atmospheric nucleation and elucidates important Particle synthesis mechanisms in the gas phase. Condensation Particle Counters (CPCs) have been widely used to measure the concentration of aerosols. However, it is challenging for the CPCs to measure Particles below 3 nm due to the insufficient activation of these Particles via vapor Condensation. Methods have been proposed to increase the saturation ratio of the condensing vapor to promote the detection efficiency of sub-3 nm Particles in the CPCs. Different working fluids also make a considerable impact on Particle detection. Given the various types of parameters and the wide range of values these parameters can take, modeling studies are needed in searching for the optimal operating conditions of a CPC. In this work, we simulated the sub-3 nm Particle activation and growth in a laminar flow CPC using COMSOL Multiphysics®, which has the advantages of simulating complex flow conditions and interfacing with post-processing software such as MATLAB. Our simulation incorporates the influence of temperature-dependent air and working fluid properties on Particle activation and the impact of latent heat and non-continuum effects on droplet growth. Following the method introduced by Iida, Stolzenburg and McMurry (2009), Particle activation is optimized for a given working fluid and condenser temperature by adjusting the saturator temperature to achieve a homogeneous nucleation rate of 1 s−1. The results, characterized by Dkel,0 (largest Particle size that cannot be activated) and Dkel,50 (Particle size activated with 50% efficiency), were compared against the analytical Graetz model used in Stolzenburg (1988). Our COMSOL simulations show that glycerine, diethylene glycol, ethylene glycol, 2-aminoethanol, and dimethyl phthalate are the best five working fluids achieving the smallest Dkel,50 among 45 commonly used solvents. The Dkel,50 values simulated by COMSOL under a condenser temperature of 10 °C for the five working fluids are 1.56, 1.88, 1.92, 1.98, and 2.10 nm, respectively, while the values simulated by the analytical Graetz solution differ slightly from 0.4% to 0.7%. The results demonstrate excellent agreement between these two simulation methods. For the five best working fluids activating the same 2.1 nm Particles, the droplets can grow to sizes detectable by a second-stage CPC. The sensitivity of the COMSOL solution to the inlet condition and the form of convective diffusion equations is investigated. We also discussed the effect of CPC operating conditions, such as the condenser geometry and flow conditions, on Particle activation for optimizing the performance of the CPC in detecting sub-3 nm Particles.
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characterization of a kanomax fast Condensation Particle Counter in the sub 10 nm range
Journal of Aerosol Science, 2021Co-Authors: Yiliang Liu, Michel Attoui, Jianmin Chen, Lin WangAbstract:Abstract A butanol-based fast Condensation Particle Counter (Fast CPC, Model 3650, Kanomax Inc., Japan) was characterized in this study with three different types of monodisperse Particles, including positively and negatively charged nickel-chromium (Ni/Cr) Particles, positively charged tetraheptyl ammonium bromide (THABr) and tetrabutyl ammonium bromide (TBABr) Particles, and positively charged polyethylene glycol (PEG) Particles. The PEG Particles were characterized with varied numbers of charges, whereby the charge number effect on Particle activation was investigated. The performance of the Fast CPC was compared with a TSI® 3775 CPC and a TSI® 3776 CPC, respectively, under both factory temperature settings and boosted temperature settings, the latter of which corresponded to the brink of butanol homogeneous nucleation. Our results show that size-resolved Ni/Cr Particles were detected by the Fast CPC with comparable detection efficiencies regardless of the charge polarity. When the charge number on a PEG Particle increased from 1 to 3, an increasing tendency of the detection efficiency was observed, hinting that multiple charges on a Particle will facilitate its activation. Particle activation was affected by the Particle chemical composition as well, which is suggested by the higher activation efficiencies of PEG Particles than those of Ni/Cr Particles. The effects of multiple charges and chemical composition on Particle activation were both more significant under factory temperature settings, but became less pronounced under boosted temperature settings. In addition to a quicker response time, the Fast CPC was capable of detecting sub-3 nm Particles under boosted temperature settings, with the detection efficiency higher than that of the 3775 CPC but lower than that of the 3776 CPC, and can be used as a good candidate for the measurement of rapidly varying concentrations of small Particles.
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B3010: a boosted TSI 3010 Condensation Particle Counter for airborne studies
Atmospheric Measurement Techniques, 2019Co-Authors: David Picard, Michel Attoui, Karine SellegriAbstract:In the present paper, we expose how we boosted the performance of a commercial Condensation Particle Counter (CPC) model TSI 3010 to detect Particles as small as 1.5 nm while preserving the robustness and reliability of the original instrument. The TSI 3010 was selected because of our deep knowledge of its internal workings and its large incorporated butanol reservoir that allows continuous operation for several hours without refill, which is well suited to airborne operation. Aside from this, it is still pretty easy to buy instruments from the TSI 3010 family from companies that specialize in used scientific instrument retail. The CPC described in this study is called B3010 hereafter, where the "B" stands for boosted. We provide an evaluation of its performances down to 1 nm using standard calibration methods and comparisons with ultrafine CPCs (TSI 3025 and TSI 3776), as well as with its original version. One important application of the B3010 is for high-altitude measurement stations and airborne studies, the instrument's detection efficiency was quantified for various inlet flow rates and pressures.
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detection near 1 nm with a laminar flow water based Condensation Particle Counter
Aerosol Science and Technology, 2017Co-Authors: Susanne V Hering, Chongai Kuang, Gregory S Lewis, Steven R Spielman, Arantzazu Eigurenfernandez, Nathan M Kreisberg, Michel AttouiAbstract:ABSTRACTPresented is a laminar-flow, water-based Condensation Particle Counter capable of Particle detection near 1 nm. This instrument employs a three-stage, laminar-flow growth tube with a “moderator” stage that reduces the temperature and water content of the output flow without reducing the peak supersaturation, and makes feasible operation at the large temperature differences necessary for achieving high supersaturations. The instrument has an aerosol flow of 0.3 L/min, and does not use a filtered sheath flow. It is referred to as a “versatile” water Condensation Particle Counter, or vWCPC, as operating temperatures can be adjusted in accordance with the cut-point desired. When operated with wall temperatures of ∼2°C, >90°C, and ∼22°C for the three stages, respectively, the vWCPC detects Particles generated from a heated nichrome wire with a 50% efficiency cut-point near 1.6 nm mobility diameter. At these operating temperatures, it also detects 10–20% of large molecular ions formed from passing filte...
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the high charge fraction of flame generated Particles in the size range below 3 nm measured by enhanced Particle detectors
Combustion and Flame, 2017Co-Authors: Yang Wang, Juha Kangasluoma, Michel Attoui, Markku Kulmala, Tuukka Petaja, Heikki Junninen, Jiaxi Fang, Pratim BiswasAbstract:Abstract Charging in flames significantly affects the properties of the resultant Particles produced because of its influence in almost all stages of Particle formation. The charging characteristics of flame-generated sub-3 nm Particles were investigated with three enhanced Particle detectors including a high resolution differential mobility analyzer (DMA) coupled with an electrometer, a Particle size magnifier coupled with a butanol-based Condensation Particle Counter (PSM-bCPC), and an atmospheric pressure interface time-of-flight mass spectrometer (APi-TOF). Up to 95% of the flame-generated sub-3 nm Particles were charged at a sampling height of 5 mm above the burner, indicating the existence of a strong ionization process in the investigated flame. This high fraction of charged Particles contradicts the classical charging theories, which predict
Tuukka Petaja - One of the best experts on this subject based on the ideXlab platform.
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the high charge fraction of flame generated Particles in the size range below 3 nm measured by enhanced Particle detectors
Combustion and Flame, 2017Co-Authors: Yang Wang, Juha Kangasluoma, Michel Attoui, Markku Kulmala, Tuukka Petaja, Heikki Junninen, Jiaxi Fang, Pratim BiswasAbstract:Abstract Charging in flames significantly affects the properties of the resultant Particles produced because of its influence in almost all stages of Particle formation. The charging characteristics of flame-generated sub-3 nm Particles were investigated with three enhanced Particle detectors including a high resolution differential mobility analyzer (DMA) coupled with an electrometer, a Particle size magnifier coupled with a butanol-based Condensation Particle Counter (PSM-bCPC), and an atmospheric pressure interface time-of-flight mass spectrometer (APi-TOF). Up to 95% of the flame-generated sub-3 nm Particles were charged at a sampling height of 5 mm above the burner, indicating the existence of a strong ionization process in the investigated flame. This high fraction of charged Particles contradicts the classical charging theories, which predict
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remarks on ion generation for cpc detection efficiency studies in sub 3 nm size range
Aerosol Science and Technology, 2013Co-Authors: Juha Kangasluoma, Joona Mikkilä, Katrianne Lehtipalo, Michel Attoui, Mikko Sipila, Markku Kulmala, Heikki Junninen, Joonas Vanhanen, D R Worsnop, Tuukka PetajaAbstract:To calibrate a newly developed Condensation Particle Counter, samples of known chemical composition are needed as the chemistry plays a role in the activation process. For that, we have built a calibration setup and produced ammonium sulfate, sodium chloride, tungsten oxide, silver, alkyl halide, and ionic liquid clusters down to 1 nm in mobility diameter in positive and negative mode. The chemical composition of most negatively charged clusters was solved using high-resolution mass spectrometer and we identified about 70% of the total signal of the mass spectrometer. For the Airmodus Particle Size Magnifier, which was the instrument to be calibrated, we measured cutoff diameters of 1.1, 1.3, 1.4, 1.6, and 1.6–1.8 nm for negative sodium chloride, ammonium sulfate, tungsten oxide, silver, and positive organics, respectively. From the alkyl halide and ionic liquid experiments, we concluded that the composition plays a bigger role than the charge state of the cluster in the activation process. We also showed...
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optimisation of the operation regimes for the water based Condensation Particle Counter
Lithuanian Journal of Physics, 2012Co-Authors: Genrik Mordas, Tuukka Petaja, Vidmantas UleviciusAbstract:A water-based Condensation Particle Counter (CPC) TSI 3785 is a new step for the ultrafine Particle measurement technique. A new instrument was examined in this study. Detection efficiency was investigated experimentally using different temperatures of the saturator and of the growth tube. The experiments showed that detection efficiency can be improved by increasing the temperature of the growth tube and decreasing the saturator temperature. Fitting a two-free parameter equation to the experimental data, the cut-sizes D50% were determined. The determined cut-sizes were comparable with the other three widely used fitting equations. The cut-sizes were studied by changing the growth tube temperature from 40 to 65 °C and varying the saturator temperature from 10 to 30 °C. For the purpose of the study, the instrument operation regime (saturator and growth tube temperatures) can be optimised by selecting the needed cut-size. The cut-sizes can be changed in a wide range. The smallest detected cut-size D50% was 4.2 nm, and the largest 14.6 nm. In the default operation regime, the instrument cut-size was 5.9 nm. The detection efficiency of the studied TSI CPC 3785 was compared with the ultrafine TSI CPC 3786. The results showed that the studied CPC can be optimised to the regime having a smaller cut-size than the cut-size of the ultrafine CPC in the default regime. Thus, the tested TSI CPC 3785 had the lowest detection limit (D50%) of 4.2 nm, and the TSI CPC 3786 had 4.6 nm for the silver Particles.
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applying the Condensation Particle Counter battery cpcb to study the water affinity of freshly formed 2 9 nm Particles in boreal forest
Atmospheric Chemistry and Physics, 2009Co-Authors: Ilona Riipinen, Mikko Sipila, Tuukka Petaja, Hanna E Manninen, Taina Ylijuuti, Michael Boy, Mikael Ehn, Heikki Junninen, Markku KulmalaAbstract:Abstract. Measurements on the composition of nanometer-sized atmospheric Particles are the key to understand which vapors participate in the secondary aerosol formation processes. Knowledge on these processes is crucial in assessing the climatic effects of secondary aerosol formation. We present data of >2 nm Particle concentrations and their water-affinity measured with the Condensation Particle Counter Battery (CPCB) at a boreal forest site in Hyytiala, Finland, during spring 2006. The data reveal that during new Particle formation events, the smallest Particles activate for growth at clearly smaller sizes in water than in butanol vapor. However, even at 2–4 nm, there are days when the Particles seem to be less hygroscopic than ammonium sulfate or sulfuric acid, which are often referred to as the most likely compounds present in atmospheric nucleation. This observation points to the possible presence of water-soluble organics, even at the very first steps on Particle formation. The water-affinity of the Particles decreases with size, indicating that the vapors that participate in the first steps of the Particle formation and growth are more hygroscopic than the vapors contributing to the later stages of the growth. This suggests that the relative role of less hygroscopic organics in atmospheric Particle growth increases as a function of Particle size.
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the Condensation Particle Counter battery cpcb a new tool to investigate the activation properties of nanoParticles
Journal of Aerosol Science, 2007Co-Authors: Markku Kulmala, Genrik Mordas, Mikko Sipila, Tuukka Petaja, Pasi Aalto, Tiia Gronholm, Hanna Vehkamaki, Anca I Hienola, Erik Herrmann, Ilona RiipinenAbstract:The formation and growth of fresh atmospheric aerosol Particles was investigated using a Condensation Particle Counter battery (CPCB). This instrument is a matrix of four separate CPCs, which differ in the combination of both cut-off size and working liquid (water; n-butanol). In a first step, the CPC counting efficiencies and cut-off sizes were carefully characterised under laboratory conditions for different condensing vapours, temperature differences between condenser and saturator, and test aerosol types. In addition, the activation process was described theoretically, and modelled numerically for the given CPC configurations. These results confirmed that water-soluble and water-insoluble as well as butanol-soluble and butanol-insoluble aerosol Particles may be discriminated in the CPCB through different activation diameters. Therefore, the CPCB represents a novel tool to infer information on the chemical composition of aerosol Particles between 2 and 20 nm. To test the applicability of the CPCB under field conditions, the CPCB was operated at a rural background station in Finland (Hyytiala) in April and May 2005. The results indicate that growing nucleation mode Particles were water-soluble both at 3 and 11 nm.