Charging of aerosol particles in the near free-molecule regime

Lushnikov, A. A.; Kulmala, Markku

doi:10.1140/epjd/e2004-00047-9

Cited by 30 publications

(20 citation statements)

References 15 publications

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“…This observation can most likely be explained by the higher stability of charged clusters over neutral ones at a certain precursor gas saturation ratio (Enghoff and Svensmark, 2008;Yue and Chan, 1979). Furthermore, charged clusters clearly activate more easily and grow more quickly (e.g., Lushnikov and Kulmala, 2004;Winkler et al, 2008;Yu and Turco, 2000). Keeping this in mind and assuming no ionion and ion-particle interactions, the time difference between an earlier occurring ion fraction and the total particle fraction during the growth process should increase or remain constant.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, it is an interesting yet open question if these observations are just a special feature of the Waldstein site, or if they can also be found elsewhere. An earlier appearance of the ion mode is plausible, as ions reduce the critical cluster size and facilitate the cluster activation (e.g., Lushnikov and Kulmala, 2004;Winkler et al, 2008;Yu and Turco, 2000;Yue and Chan, 1979). To, at least partly, explain the difference in the growth rates we have proposed a mechanism including ion-ion recombination and ion-particle attachment (cf.…”

Section: Discussionmentioning

confidence: 99%

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Ion – particle interactions during particle formation and growth at a coniferous forest site in central Europe

et al. 2014

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Abstract. In this work, we examined the interaction of ions and neutral particles during atmospheric new particle formation (NPF) events. The analysis is based on simultaneous field measurements of atmospheric ions and total particles using a neutral cluster and air ion spectrometer (NAIS) across the diameter range 2-25 nm. The Waldstein research site is located in a spruce forest in NE Bavaria, Southern Germany, known for enhanced radon concentrations, presumably leading to elevated ionization rates. Our observations show that the occurrence of the ion nucleation mode preceded that of the total particle nucleation mode during all analyzed NPF events. The time difference between the appearance of 2 nm ions and 2 nm total particles was typically about 20 to 30 min. A cross correlation analysis showed a rapid decrease of the time difference between the ion and total modes during the growth process. Eventually, this time delay vanished when both ions and total particles did grow to larger diameters. Considering the growth rates of ions and total particles separately, total particles exhibited enhanced growth rates at diameters below 15 nm. This observation cannot be explained by condensation or coagulation, because these processes would act more efficiently on charged particles compared to neutral particles. To explain our observations, we propose a mechanism including recombination and attachment of continuously present cluster ions with the ion nucleation mode and the neutral nucleation mode, respectively.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Ion – particle interactions during particle formation and growth at a coniferous forest site in central Europe

et al. 2014

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“…The mass transfer of the organic vapour between the gas phase and particles is simulated using a version of the condensation equation of Fuchs and Sutugin (1971) which takes into account mirror Coulomb interactions (Lushnikov and Kulmala, 2004). The mass accommodation coefficient of the organic vapour is assumed unity.…”

Section: Model Descriptionmentioning

confidence: 99%

Kinetic nucleation and ions in boreal forest particle formation events

et al. 2004

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Abstract. In order to gain a more comprehensive picture on different mechanisms behind atmospheric particle formation, measurement results from QUEST 2-campaign are analyzed with an aid of an aerosol dynamic model. A special emphasis is laid on air ion and charged aerosol dynamics. Model simulations indicate that kinetic nucleation of ammonia and sulphuric acid together with condensation of sulphuric acid and low-volatile organic vapours onto clusters and particles explain basic features of particle formation events as well as ion characteristics. However, an observed excess of negative ions in the diameter range 1.5-3 nm and overcharge of 3-5 nm particles demonstrate that ions are also involved in particle formation. These observations can be explained by preferential condensation of sulphuric acid onto negatively charged clusters and particles and/or contribution of ion-induced nucleation on particle formation. According to model simulations, which assume that the nucleation rate is equal to the sulfuric acid collision rate, the relative contribution of ion-based particle formation seems to be smaller than kinetic nucleation of neutral clusters. Conducted model simulations also corroborate the recently-presented hypothesis according to which a large number of so-called thermodynamically stable clusters (TSCs) having a diameter between 1-3 nm exist in the atmosphere. TSCs were found to grow to observable sizes only under favorable conditions, e.g. when the pre-existing particle concentration was low.

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“…We take this into account by multiplying the molar flux onto a particle surface with the following factor (Lushnikov and Kulmala, 2004):…”

Section: Condensationmentioning

confidence: 99%

“…Condensation of polar vapors, such as sulfuric acid, is enhanced by the presence of charges in the growing nuclei (Laakso et al, 2003;Nadykto and Yu, 2003;Lushnikov and Kulmala, 2004). Charges also influence nuclei coagulation rates, the effect of which is most pronounced for nuclei of opposite charge (e.g., Hoppel and Frick, 1986;Hõrrak et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Atmospheric new particle formation: real and apparent growth of neutral and charged particles

et al. 2011

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Abstract. In this study we have provided simple analytical formulae to estimate the growth rate of a nucleation mode due to self-coagulation and the apparent growth rate due to coagulation scavenging by larger particles. These formulae were used on a set of simulations covering a wide range of atmospheric conditions. The modal growth rates were determined from the simulation results by summing the contribution of each process, by calculating the increase rate in the count mean diameter of the mode and by following the peak concentration of the mode. The results of these three methods were compared with each other and the means used to estimate the growth rate due to self-coagulation and coagulation scavenging were found to give accurate values. We also investigated the role of charged particles and electric interactions in the growth of a nucleation mode. Charged particles were found to increase the growth rate due to both self-coagulation and coagulation scavenging by a factor of ∼1.5 to 2. In case of increased condensation onto charged particles, the total condensational growth rate of a nucleation mode may increase significantly in the very early steps of the growth. The analytical formulae provided by this paper were designed to provide the growth rates due to different processes from aerosol dynamic simulations, but the same principles can be used to determine the growth rates from measurement data.

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Charging of aerosol particles in the near free-molecule regime

Cited by 30 publications

References 15 publications

Ion – particle interactions during particle formation and growth at a coniferous forest site in central Europe

Ion – particle interactions during particle formation and growth at a coniferous forest site in central Europe

Kinetic nucleation and ions in boreal forest particle formation events

Atmospheric new particle formation: real and apparent growth of neutral and charged particles

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