The condensation particle counter battery (CPCB): A new tool to investigate the activation properties of nanoparticles

Kulmala, M; Mordas, G; Petaja, T; Gronholm, T; Aalto, PP; Vehkamaki, H; Hienola, AI; Herrmann, E; Sipila, M; Riipinen, I; Manninen, HE; Hameri, K; Stratmann, F; Bilde, M; Winkler, PM; Birmili, W; Wagner, PE
2007 | J Aerosol Sci | 38 (3) (289-304)

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 wits 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 tinder field conditions, the CPCB was operated at a rural background station in Finland (Hyytiata) in April and May 2005. The results indicate that growing nucleation mode particles were water-soluble both at 3 and 11 nm. (c) 2006 Elsevier Ltd. All rights reserved.

Identification and classification of the formation of intermediate ions measured in boreal forest

Hirsikko, A; Bergman, T; Laakso, L; Dal Maso, M; Riipinen, I; Horrak, U; Kulmala, M
2007 | Atmos. Chem. Phys. | 7 (201-210)

We have measured the size distributions of air ions (0.42 - 7.5 nm in diameter) with the Balanced Scanning Mobility Analyzer in boreal forest, in Southern Finland since spring 2003. The size range covers the size range of cluster ions ( approximately 0.42 - 1.6 nm) and naturally charged nanometre aerosol particles ( 1.6 - 7.5 nm) or intermediate air ions. Based on the measurements from April 2003 to March 2006 we studied the characteristics of charged aerosol particle formation by classifying each day either as a particle formation event, undefined or non-event day. The principal of the classification, as well as the statistical description of the charged aerosol particle formation events are given. We found in total 270 (26% of the analysed days) and 226 (22% of the analysed days) particle formation days for negative and positive intermediate ions, respectively. For negatively charged particles we classified 411 (40% of the analysed days) undefined and 348 (34% of the analysed days) nonevent days whereas for positively charged particles 343 (33% of the analysed days) undefined and 460 (45% of the analysed days) non-event days. The results were compared with the ordinary classification based on the Differential Mobility Particle Sizer ( DMPS) measurements carried out at the same place. The above-presented values differed slightly from that found from the DMPS data, with a lower particle diameter of 3 nm. In addition, we have found the rain-induced intermediate ion bursts frequently. The rain effect was detected on 163 days by means of negative ions and on 105 days by positive ones. Another interesting phenomenon among the charged aerosol particles was the appearance and existence of intermediate ions during the snowfall. We observed this phenomenon 24 times with negatively charged particles and 21 times with positively charged ones during winter months ( October - April). These intermediate air ions were seen during the snowfall and may be caused by ice crystals, although the origin of these intermediate ions is unclear at the moment.

Connections between atmospheric sulphuric acid and new particle formation during QUEST III-IV campaigns in Heidelberg and Hyyti

Riipinen, I; Sihto, SL; Kulmala, M; Arnold, F; Dal Maso, M; Birmili, W; Saarnio, K; Teinila, K; Kerminen, VM; Laaksonen, A; Lehtinen, KEJ
2007 | Atmos. Chem. Phys. | 7 (8) (1899-1914)

This study investigates the connections between atmospheric sulphuric acid and new particle formation during QUEST III and BACCI/QUEST IV campaigns. The campaigns have been conducted in Heidelberg ( 2004) and Hyytiala ( 2005), the first representing a polluted site surrounded by deciduous forest, and the second a rural site in a boreal forest environment. We have studied the role of sulphuric acid in particle formation and growth by determining 1) the power-law dependencies between sulphuric acid ([H(2)SO(4)]), and particle concentrations (N(3-6)) or formation rates at 1 nm and 3 nm (J(1) and J(3)); 2) the time delays between [H(2)SO(4)] and N(3-6) or J(3), and the growth rates for 1-3 nm particles; 3) the empirical nucleation coefficients A and K in relations J(1)= A[H(2)SO(4)] and J(1)= K[H(2)SO(4)](2), respectively; 4) theoretical predictions for J(1) and J(3) for the days when no significant particle formation is observed, based on the observed sulphuric acid concentrations and condensation sinks. In both environments, N(3-6) or J(3) and [H(2)SO(4)] were linked via a power-law relation with exponents typically ranging from 1 to 2. The result suggests that the cluster activation theory and kinetic nucleation have the potential to explain the observed particle formation. However, some differences between the sites existed: The nucleation coefficients were about an order of magnitude greater in Heidelberg than in Hyytiala conditions. The time lags between J(3) and [H(2)SO(4)] were consistently lower than the corresponding delays between N(3-6) and [H(2)SO(4)]. The exponents in the J(3) proportional to[H(2)SO(4)](nJ 3)-connection were consistently higher than or equal to the exponents in the relation N(3-6) proportional to[H(2)SO(4)](nN36). In the J(1) values, no significant differences were found between the observed rates on particle formation event days and the predictions on non-event days. The J(3) values predicted by the cluster activation or kinetic nucleation hypotheses, on the other hand, were considerably lower on non-event days than the rates observed on particle formation event days. This study provides clear evidence implying that the main process limiting the observable particle formation is the competition between the growth of the freshly formed particles and their loss by scavenging, rather than the initial particle production by nucleation of sulphuric acid. In general, it can be concluded that the simple models based on sulphuric acid concentrations and particle formation by cluster activation or kinetic nucleation can predict the occurence of atmospheric particle formation and growth well, if the particle scavenging is accurately accounted for.

Hot-air balloon measurements as a platform for boundary layer profile measurements during new particle formation

Laakso, L.; Grönholm, T.; Kulmala, L.; Haapanala, S.; Hirsikko, A.; Lovejoy, E. R.; Kazil, J.; Kurtén, T.; Boy, M.; Nilsson, E. D.; Sogacheva, A.; Riipinen, I.; Stratman, F.; Kulmala, M.
2007 | Boreal Environ. Res. | 12 (279-294)

Aerosol size distribution measurements at four Nordic field stations: identification, analysis and trajectory analysis of new particle formation bursts

Dal Maso, M.; Sogacheva, L.; Aalto, P.P.; Riipinen, I.; Komppula, M.; Tunved, P.; Korhonen, L.; Suur-Uski, V.; Hirsikko, A.; Kurten, T.; Kerminen, V.M.; Lihavainen, H.; Viisanen, Y.; Hansson, H.-C.; Kulmala, M.
2007 | Tellus B Chem Phys Meteorol | 59 (3) (350-361)
atmospheric particles , boreal forest , growth , hyytiala , nucleation events , smear-ii , southern finland

We analyzed aerosol size distributions from the Finnish measuring stations at Hyytiala, Varrio and Pallas and the Swedish station at Aspvreten over a period of several years. We identified occurrences of new particle formation bursts and obtained characteristics for the bursts from the size distribution data. In addition, we analyzed the directions from which air masses leading to new particle formation arrived. We found that new particle formation occurs over the whole area covered by the measurement stations. The Northern Atlantic is dominating as a source for air leading to new particle formation at all of the analyzed stations. The formation occurrence had a similar annual variation at all the stations, with peaks in springtime and autumn and minima in winter and summer. The ratio of event days to non-event days had a North-South dependence, with northern stations having lower event ratios. Particle growth rates ranged from 0.5 to 15 nm/h, with the mean growth rate being slightly higher at the southern stations. Southern stations also had a stronger particle source, on average 0.5 cm(-3) s(-1), compared to the northern stations (0.1 cm(-3) s(-1)). Based on our analysis, it is evident that new particle formation occurs often in whole Nordic boreal forest area when air is transported from the North Atlantic, and that the same process or processes are very probably responsible for the formation over the whole area.

Adipic and malonic acid aqueous solutions: Surface tensions and saturation vapor pressures

Riipinen, I; Koponen, IK; Frank, GP; Hyvaerinen, AP; Vanhanen, J; Lihavainen, H; Lehtinen, KEJ; Bilde, M; Kulmala, M
2007 | JOURNAL OF PHYSICAL CHEMISTRY A | 111 (50) (12995-13002)

The surface tension of adipic aqueous solutions was measured as a function of temperature (T = 278-313 K) and adipic acid mole fraction (X = 0.000-0.003) using the Wilhelmy plate method. A parametrization fitted to these data is presented. The evaporation rates of binary water-malonic and water-adipic acid droplets were measured with a TDMA technique at different temperatures (T = 293-300 K) and relative humidities (58-80%), and the saturation vapor pressures of subcooled liquid malonic and adipic acids were derived from the data using a binary evaporation model. The temperature dependence of the vapor pressures was obtained as least-squares fits to the derived vapor pressures: ln(P(sat,l)) (Pa) = 220.2389 - 22634.96/T (K) - 26.66767 In T (K) for malonic acid and ln(P(sat,l)) (Pa) = 140.6704 - 18230.97/T (K) - 15.48011 In T (K) for adipic acid.

Toward direct measurement of atmospheric nucleation

Kulmala, M; Riipinen, I; Sipila, M; Manninen, HE; Petaja, T; Junninen, H; Dal Maso, M; Mordas, G; Mirme, A; Vana, M; Hirsikko, A; Laakso, L; Harrison, RM; Hanson, I; Leung, C; Lehtinen, KEJ; Kerminen, VM
2007 | Science | 318 (5847) (89-92)

Atmospheric aerosol formation is known to occur almost all over the world, and the importance of these particles to climate and air quality has been recognized. Although almost all of the processes driving aerosol formation take place below a particle diameter of 3 nanometers, observations cover only larger particles. We introduce an instrumental setup to measure atmospheric concentrations of both neutral and charged nanometer-sized clusters. By applying the instruments in the field, we come to three important conclusions: (i) A pool of numerous neutral clusters in the sub-3 nanometer size range is continuously present; (ii) the processes initiating atmospheric aerosol formation start from particle sizes of similar to 1.5 nanometers; and (iii) neutral nucleation dominates over the ion-induced mechanism, at least in boreal forest conditions.

Hot-air balloon as a platform for boundary layer profile measurements during particle formation

Laakso, L; Gronholm, T; Kulmala, L; Haapanala, S; Hirsikko, A; Lovejoy, ER; Kazil, J; Kurten, T; Boy, M; Nilsson, ED; Sogachev, A; Riipinen, I; Stratmann, F; Kulmala, M
2007 | Boreal Environ. Res. | 12 (3) (279-294)

In this study, we used a hot-air balloon as a platform for boundary layer particle and cluster measurements. We did altogether I I flights during the springs of 2005 and 2006. During the spring of 2006, we observed five new-particle formation days. During all days, newparticle formation took place in the mixed boundary layer. During one of the days, we observed particle formation in the free troposphere, separate from that of the mixed layer. The observations showed that the concentration of freshly-formed 1.5-2 nm negative ions was several times higher than the concentration of positive ions. We also clearly observed that nucleation during one of the days, 13 March 2006, was a combination of neutral and ion-induced nucleation. Durmg some of the days, particle growth stopped at around 3 mn, probably due to lack of condensable organic vapours. Simulations of boundary layer dynamics showed that particles are formed either throughout the mixed layer or in the lower part of it, not at the top of the layer.

Thermodynamic properties of malonic, succinic, and glutaric acids: Evaporation rates and saturation vapor pressures

Koponen, IK; Riipinen, I; Hienola, A; Kulmala, M; Bilde, M
2007 | Environ. Sci. Technol. | 41 (11) (3926-3933)

This work provides thermodynamic data, in particular, liquid-state saturation vapor pressures of three common slightly water soluble secondary organic aerosol components, namely, malonic, succinic, and glutaric acids. A modified tandem differential mobility analyzer system was used to measure evaporation rates of nanometer sized aqueous malonic, succinic, and glutaric acid droplets at relative humidities and temperatures relevant in the lower troposphere. Liquid phase saturation vapor pressures and other thermodynamic properties were derived from the measure ments using a binary condensation model. The obtained expressions for liquid phase saturation vapor pressures compare well with extrapolated literature data. The importance of the choice of method for calculating activity coefficients is discussed.

A method for determining thermophysical properties of organic material in aqueous solutions: Succinic acid

Riipinen, I; Svenningsson, B; Bilde, M; Gaman, A; Lehtinen, KEJ; Kulmala, M
2006 | Atmos. Res. | 82 (3-4) (579-590)

A method for determining evaporation rates and thermodynamic properties of aqueous solution droplets is introduced. The method combines evaporation rate measurements using modified TDMA technique with data evaluation using an accurate evaporation model. The first set of data has been collected and evaluated for succinic acid aqueous solution droplets. Evaporation rates of succinic acid solution droplets have been measured using a TDMA system at controlled relative humidity (65%) and temperature (298K). A temperature-dependent expression for the saturation vapour pressure of pure liquid phase succinic acid at atmospheric temperatures has been derived by analysing the evaporation rate data with a numerical model. The obtained saturation vapour pressure of liquid phase succinic acid is ln(p)= 118.41 - 16204.8/T - 12.452ln(T). The vapour pressure is in unit of Pascal and the temperature in Kelvin. A linear expression for the enthalpy of vaporization for liquid state succinic acid is also presented. According to the results presented in the following, a literature expression for the vapour pressure of liquid phase succinic acid defined for temperatures higher than 461 K [Yaws, C.L., 2003. Yaws' Handbook of Thermodynamic and Physical Properties of Chemical Compounds, Knovel] can be extrapolated to atmospheric temperatures with very good accuracy. The results also suggest that at 298 K the mass accommodation coefficient of succinic acid is unity or very close to unity. (c) 2006 Elsevier B.V. All rights reserved.

Atmospheric sulphuric acid and aerosol formation: implications from atmospheric measurements for nucleation and early growth mechanisms

Sihto, S.-L.; Kulmala, M.; Kerminen, V.-M.; Dal Maso, M.; Petäjä, T.; Riipinen, I.; Korhonen, H.; Arnold, F.; Janson, R.; Boy, M.; Laaksonen, A.; Lehtinen, K.E.J.
2006 | Atmos. Chem. Phys. | 6 (4079-4091)

Theoretical and experimental study on phase transitions and mass fluxes of supersaturated water vapor onto different insoluble flat surfaces

Lauri, A; Riipinen, I; Ketoja, JA; Vehkamaki, H; Kulmala, M
2006 | Langmuir | 22 (24) (10061-10065)

The heterogeneous nucleation and condensation of water vapor onto three different surfaces (newsprint paper, Teflon, cellulose film) was studied theoretically and experimentally. The theoretical framework included the use of the classical theory of heterogeneous nucleation, diffusion theory corrected with transition regime correction factors, and the theory of heat transfer. Experiments were carried out using an environmental scanning electron microscope (ESEM). The experimental results for newsprint paper were investigated more closely. Our results show that the measured onset supersaturations were smaller than the modeled ones when the experimentally determined contact angle was used. Furthermore, the measured condensational growth rates were smaller than the modeled ones, presumably resulting from the approximations that had to be made in the calculations.

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