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The counting efficiencies of 2 different types of diethylene-glycol (DEG) based Condensation Particle Counters (CPCs) is described and discussed. The development of two laminar flow CPCs, sensitive in the size range below 3 nm is described. The two types used are a modified TSI 3776 laminar diffusion-type CPC operating with DEG instead of butanol (DEG-CPC) and a turbulent mixing Particle Size Magnifier (PSM) A09 from Airmodus. For each of the two types two different systems with slightly different settings have been investigated, respectively. The two laminar flow CPCs were operated at different temperature settings, where one of the mixing type systems was running at a fixed saturation ratio and therefore had a fixed cut-off diameter and the other one was opaerated in scanning mode. Various different test aerosols have been generated to obtain cut-off curves for all four different CPCs. The main focus was on measuring the counting efficiencies under well controlled laboratory conditions. Therefore a high resolution mass spectrometer was used in the setup as well. [ABSTRACT FROM AUTHOR]

Industrial activity is a major source of sulphur compound emissions. The sulphuric acid and sulphur dioxide measurements in the vicinity of the industrial area and the oil refinery in Kilpilahti expressed great variation in concentration. The hourly mean values of concentration were categorized according to the area from where the air mass was travelling towards the measurement site. The statistical characteristics and diurnal behavior of emissions between these areas were significantly different. [ABSTRACT FROM AUTHOR]

We have run a set of experiments in the CLOUD chamber at CERN, Switzerland, studying the effect of dimethylamine (DMA) on sulfuric acid (SA)-water nucleation using a nitrate based Chemical Ionization Atmospheric Pressure ionization Time-Of-Flight Mass Spectrometer (CI-APi-TOF). Experiment was designed to produce neutral high m/z SA-DMA clusters in close to atmospherically relevant conditions to be detected and characterized by the CI-APi-TOF. We aimed in filling up the gap in measurement techniques from molecular level up to climatically relevant aerosol particles and thus improve our understanding of the role of sulfuric acid and DMA in atmospheric nucleation. [ABSTRACT FROM AUTHOR]

The mechanisms behind the nucleation of vapors forming new particles in the atmosphere had been proven difficult to establish. One main aim of the CLOUD experiment was to explore in detail these first steps of atmospheric new particle formation by performing extremely well controlled laboratory experiments. We examined nucleation and growth in the presence of different mixtures of vapors, including sulfuric acid, ammonia, dimethylamine, and oxidation products of pinanediol or α-pinene. Among the employed state-of-the-art instrumentation, a high-resolution mass spectrometer that directly sampled negatively charged ions and clusters proved particularly useful. We were able to resolve most of the chemical compositions found for charged sub-2nm clusters and to observe their growth in time. These compositions reflected the mixture of condensable vapors in the chamber and the role of each individual vapor in forming sub-2nm clusters could be explored. By inter-comparing between individual experiments and ambient observations, we try to establish which vapors participate in nucleation in the actual atmosphere, and how. [ABSTRACT FROM AUTHOR]

The role of ion-ion recombination in new particle formation is still unclear. In this work, we present a new method to estimate the size distribution of recombination products from atmospheric measurements. By applying our method to size distributions of charged and neutral clusters measured in Hyytia¨la¨, Finland, we show that only a minor fraction of all sub-2nm neutral clusters originate from ion-ion recombination in boreal forest conditions. [ABSTRACT FROM AUTHOR]

The research of atmospheric new particle formation has proceeded lately as the role of sulphuric acid has been established. Still, the roles of other atmospheric compounds in nucleation remain largely unclear. To clarify the first steps of atmospheric new particle formation extensive nucleation experiments were performed in CLOUD chamber in 2012. Especially the role of oxidations products of α-pinene was studied in detail. The experiments provided new information about the part of oxidized organics in nucleation. [ABSTRACT FROM AUTHOR]

We built a new instrumental setup for measuring ion distributions in the size range [1.3-6] nm. The implementation of an high transmission inlet increased the total transmission efficiency to more than 6% at 1.47 nm mobility equivalent diameter, allowing the detection of ions at atmospheric concentrations. The size resolution of our measurements is as high as 6. We characterized the instrument in the laboratory and carried out measurements during the CLOUD7 campaign. We compared the results obtained with the Neutral cluster and Air Ion spectrometer finding very good agreement. [ABSTRACT FROM AUTHOR]

Atmospheric new particle formation is the dominant source of aerosol particles in the global atmosphere and an important player in aerosol climatic effects. The key steps of this process occur in the sub-2 nm size range. We have recently shown that at a lower-troposphere site (Hyytia¨la¨, Southern Finland) with abundant biogenic emissions and moderate anthropogenic influence, based on comprehensive observations of atmospheric clusters in the size range of 1-2 nm mobility diameter, there are significant differences between neutral and charged cluster properties. The differences are with respect to cluster size and chemical composition, and whether the observations were made in background conditions or during periods of active aerosol formation. According to our results, sub-2 nm clusters were always present and cluster concentrations were dominated by neutral ones in all sizes and almost all the time, indicating that cluster formation and their subsequent growth i.e. atmospheric aerosol formation were dominated by neutral pathways. [ABSTRACT FROM AUTHOR]

Nucleation and subsequent growth of particles was studied in the CLOUD7 chamber experiment at Cern. Experiments were performed in varying concentrations of sulphuric acid, ammonia, dimethylamine and α-pinene, and using both ozone and hydroxyl radicals as oxidizers. Particle growth rates were determined at size ranges <1.5 nm, 1.5-3 nm, and >3nm. Comparison of the growth to the amount oxidized organics in the mass range 300-450 amu was made. [ABSTRACT FROM AUTHOR]

The Particle Size Magnifier lowers the cut-off size of a Condensation Particle Counter even down to about 1 nm in mobility diameter. By scanning the supersaturation also size information of the particles can be gained. We demonstrated that the PSM can detect particles starting from molecular sizes. By combining the data with newly developed mass spectrometric methods particle formation and growth can be followed molecule by molecule. [ABSTRACT FROM AUTHOR]

Growth rates of recently born nanometer-scale particles were measured during the CLOUD experiments at CERN. Combining the data from several recently developed measurement techniques allowed us to follow the growth of the particles starting from molecules to molecular clusters and finally to climatically relevant particles. We studied the binary system with sulphuric acid and water, and the ternary systems with ammonia or dimethylamine added to the chamber, both in purely neutral situation, and with ionization from cosmic rays or the CERN particle beam. [ABSTRACT FROM AUTHOR]

Alpha-pinene oxidation was studied in the CERN CLOUD chamber under near atmospheric conditions using varying levels of different oxidizers (i.e., O3, HOx and NOx with differing gas mixture compositions) in the presence and absence of UV-radiation, SO2 and additional organic traces; ammonia (NH3) and dimethylamine (DMA). The oxidation products and their evolution due to aging in the chamber were studied using a novel CI-APi-TOF technique, with the nitrate ion (NO3-) based chemical ionization (CI) scheme. We aimed to the results that would indicate how different oxidizing pathways lead to different product distributions in the product clusters detected. [ABSTRACT FROM AUTHOR]

A size-resolved condensation particle counter battery (SR-CPCb) was developed to infer the composition of freshly nucleated aerosol down to 1 nm in diameter. This was accomplished by exploiting the strong dependence of CPC counting efficiency on particle composition and CPC working fluid. The SR-CPCb consists of CPCs that are optimized for sub 2 nm particle detection using the following working fluids: diethylene glycol, water, and butanol. Laboratory characterizations of the SR-CPCb were performed for challenge aerosols of various compositions down to 1 nm in diameter. [ABSTRACT FROM AUTHOR]