Ion-induced Nucleation Research Articles

Ion induced nucleation of charged droplets enhanced by external electric field

The nucleation theory of charged particles in an external electric field environment is considered. The Gibbs free energy and nucleation rate changes of ion-induced nucleation under an external electric field are studied. The Classical Kelvin–Thomson equation and the ion-induced nucleation theory in the external electric field environment are corrected. The results show that the presence of an electric field can reduce the Gibbs free energy of nucleation and increase the nucleation rate. For particles larger than a few nanometers in size, the impact of the external electric field on reducing the condensation saturation ratio is more pronounced than the combined influence of the Thomson effect and dipole–charge interaction.

A cluster-of-functional-groups approach for studying organic enhanced atmospheric cluster formation

Abstract. The role of organic compounds in atmospheric new particle formation is difficult to disentangle due to the myriad of potentially important oxygenated organic molecules (OOMs) present in the atmosphere. Using state-of-the-art quantum chemical methods, we here employ a novel approach, denoted the “cluster-of-functional-groups” approach, for studying the involvement of OOMs in atmospheric cluster formation. Instead of the usual “trial-and-error” approach of testing the ability of experimentally identified OOMs to form stable clusters with other nucleation precursors, we here study which, and how many, intermolecular interactions are required in a given OOM to form stable clusters. In this manner we can reverse engineer the elusive structure of OOM candidates that might be involved in organic enhanced atmospheric cluster formation. We calculated the binding free energies of all combinations of donor and acceptor organic functional groups to investigate which functional groups most preferentially bind with each other and with other nucleation precursors such as sulfuric acid and bases (ammonia, methyl-, dimethyl- and trimethylamine). We find that multiple carboxyl groups lead to substantially more stable clusters compared to all other combinations of functional groups. Employing cluster dynamics simulations, we investigate how a hypothetically OOM composed of multiple carboxyl groups can stabilize sulfuric acid–base clusters and provide recommendations for potential atmospheric multi-carboxylic acid tracer compounds that should be explicitly studied in the future. The presented “cluster-of-functional-groups” approach is generally applicable and can be employed in many other applications, such as ion-induced nucleation and potentially in elucidating the structural patterns in molecules that facilitate ice nucleation.

Aggregation and Charging of Mineral Cloud Particles under High-energy Irradiation

It is known from Earth that ionizing high-energy radiation can lead to ion-induced nucleation of cloud condensation nuclei in the atmosphere. Since the amount of high-energy radiation can vary greatly based on the radiative environment of a host star, understanding the effect of high-energy radiation on cloud particles is critical to understand exoplanet atmospheres. This study aims to explore how high-energy radiation affects the aggregation and charging of mineral cloud particles. We present experiments conducted in an atmosphere chamber on mineral SiO2 particles with diameters of 50 nm. The particles were exposed to gamma radiation in either low-humidity (RH ≈ 20%) or high-humidity (RH > 50%) environments. The aggregation and charging state of the particles were studied with a scanning mobility particle sizer. We find that the single SiO2 particles (N1) cluster to form larger aggregates (N2–N4), and that this aggregation is inhibited by gamma radiation. We find that gamma radiation shifts the charging of the particles to become more negative by increasing the charging state of negatively charged particles. Through an independent t-test, we find that this increase is statistically significant within a 5% significance level for all aggregates in the high-humidity environment and all except the N1 particles in the low-humidity environment. For the positively charged particles, the changes in charging state are not within the 5% significance level. We suggest that the overall effect of gamma radiation could favor the formation of a high number of small particles over a lower number of larger particles.

Unexpected enhancement of sulfuric acid-driven new particle formation by alcoholic amines: The role of ion-induced nucleation

New particle formation (NPF) contributes more than half of the global aerosol. Diethanolamine (DEA) and methyldiethanolamine (MDEA) are the most common amines used to remove CO2 and H2S, which are lost to the atmosphere from CO2 chemical absorbers, livestock and consumer products and are involved in sulfuric acid (SA)-driven NPF. Ion-induced nucleation (IIN) is an important nucleation pathway for NPF. We investigated the role of IIN on DEA and MDEA enhancing SA-driven NPF using density functional method (DFT), molecular dynamics (MD) simulation and atmospheric cluster dynamics code (ACDC). The effects of SO42−, H3O+, NH4+, HSO4−, NO3−, ammonia, methylamine, dimethylamine, trimethylamine and water (W) on the nucleation of SA-DEA were further investigated. The enhancement ability of DEA is greater than that of dimethylamine (DMA) and MDEA. Participation in SA-based NPF is a removal pathway for DEA and MDEA. DEA-SA clusters are generated that not only aggregate DEA and SA molecules, but also increase further growth of atmospheric ions. The very low Gibbs formation free energy highlights the importance of ion-induced nucleation for SA-based NPF. The order of the ability of common atmospheric ions to increase the (SA)(DEA) cluster nucleation is SO42− > H3O+ > NH4+ > HSO4− > NO3−. The addition of 20 water molecules increases the (SA)(DEA)9 cluster from 1.882 nm to 2.053 nm, promoting SA-based NPF. The atmospheric ions accelerate the aggregation rate of the (SA)5(DEA)5 cluster within 15 ns?

Nucleation by a charged particle in fluids containing salt

We present a model to describe ion-induced nucleation in fluids. Nucleation is induced by a charged molecular aggregate, a large ion, a charged colloid, or an aerosol particle. This model generalizes the Thomson model to polar environments. Solving the Poisson-Boltzmann equation, we find the potential profiles around the charged core and calculate the energy. Our results are analytical in the Debye-Hückel limit and numerical otherwise. From the Gibbs free energy curve vs. nucleus size, we find the metastable and stable states and the energy barrier between them, for varying saturation values, core's charge, and amount of salt. The nucleation barrier decreases with increasing core charge or Debye length. We calculate the phase lines in the phase diagram of supersaturation and core charge. We find regions of one phase, electro-prewetting, spontaneous nucleation, ion-induced nucleation, and classical-like nucleation.

Heterogeneous Ion-Induced Nucleation of Water and Butanol Vapors Studied via Computational Quantum Chemistry beyond Prenucleation and Critical Cluster Sizes.

Water and butanol are used as working fluids in condensation particle counters, and condensation of a single vapor onto an ion can be used as a simple model system for the study of ion-induced nucleation in the atmosphere. Motivated by this, we examine heterogeneous nucleation of water (H2O) and n-butanol (BuOH) vapors onto three positively (Li+, Na+, K+) and three negatively charged (F-, Cl-, Br-) ions using classical nucleation theory and computational quantum chemistry methods. We study phenomena that cannot be captured by Kelvin-Thomson equation for small nucleation ion cores. Our quantum chemistry calculations reveal the molecular mechanism behind ion-induced nucleation for each studied system. Typically, ions become solvated from all sides after several vapor molecules condense onto the ion. However, we show that the clusters of water and large negatively charged ions (Cl- and Br-) thermodynamically prefer the ion being migrated to the cluster surface. Although our methods generally do not show clear sign-preference for ion-water nucleation, we identified positive sign-preference for ion-butanol nucleation caused by the possibility to form stabilizing hydrogen bonds between butanol molecules condensed onto a positively charged ion. These bonds cannot form when butanol condenses onto a negatively charged ion. Therefore, we show that ion charge, its sign, as well as vapor properties have effects on the prenucleation and critical cluster/droplet sizes and also on the molecular mechanism of ion-induced nucleation.

Mechanistic understanding of rapid H2SO4-HNO3-NH3 nucleation in the upper troposphere

The upper troposphere (UT) nucleation is thought to be responsible for at least one-third of the global cloud condensation nuclei. Although NH3 was considered to be extremely rare in the UT, recent studies show that NH3 is convected aloft, promoting H2SO4-HNO3-NH3 rapid nucleation in the UT during the Asian monsoon. In this study, the roles of HNO3, H2SO4 (SA), and NH3 in the nucleation of SA-HNO3-NH3 were investigated by quantum chemical calculation and molecular dynamic (MD) simulations at the level of M06-2×/6–31 + G (d, p). The nucleation ability of SA-HNO3-NH3 is suppressed as the temperature increases in the UT. The results indicated that bisulfate (HSO4−), nitrate (NO3−), and ammonium (NH4+) ionized from SA, HNO3, and NH3, respectively, can significantly enhance the nucleation ability of SA-HNO3-NH3. In addition, hydrated hydrogen ion (H3O+) as well as sulfate ions (SO42−) ionized by SA can also actively participate in the process of ion-induced nucleation. The results reveal that the enhancement effect of five ions on the SA-HNO3-NH3 nucleation can be ordered as follows: SO42− > H3O+ > HSO4− > NO3− > NH4+. Many ion-induced nucleation pathways of SA-HNO3-NH3 with the Gibbs free energies of formation (ΔG) lower than −100 kcal mol−1 were energetically favorable. HNO3 and NH3 can promote the nucleation of SA-HNO3-NH3 and water (W) molecules are also beneficial to promote the new particle formation (NPF) of SA-HNO3-NH3. Under the action of H-bonds and electrostatic interaction, ion-induced nucleation could lead to the rapid nucleation of H2SO4-HNO3-NH3 in the UT.

The neglected autoxidation pathways for the formation of highly oxygenated organic molecules (HOMs) and the nucleation of the HOMs generated by limonene

Recent ambient atmospheric measurements have observed highly oxygenated organic molecules (HOMs) at a number of sites. Monoterpenes, in particular, are inclined to autoxidize to form HOMs with different oxidants such as OH and O3. However, little is known about the formation and nucleation of the HOMs in the presence of water (W). In this study, we investigated oxidation mechanism of O3 addition to limonene in the gas and water phase by theoretical chemistry calculations. Besides, the mechanism of the formation of HOMs from photochemical reactions of limonene and the role of HOMs in new particle formation (NPF) with aerosol nucleation precursors, including sulfuric acid (SA), W and ions were investigated by means of molecular dynamics (MD) simulations and theoretical chemistry calculations. The rate constants of initiation reactions for O3 addition to limonene are suppressed as the temperature increases. In the process of ion-induced nucleation, HOMs can dominate the initial nucleation steps. The MD results indicated that HOMs can self-aggregate into clusters and W molecules are beneficial to promote the NPF of HOMs. In addition, the nucleation ability of HOMs have significant correlation with the oxygen-to-carbon (O/C) ratio of HOMs. The theoretical results proved the neglected autoxidation pathways including (i) the formation of an endoperoxide moiety in HOMs (ii) a CO2 elimination in presence of an unsaturated peroxy acyl radical. The current study provide valuable insight into NPF mechanism of (HOMs) (SA) and (HOMs) (ion) in the presence of W.

Specifics of Electrostatic Precipitation of Fly Ash from Small-Scale Fossil Fuel Combustion

This paper investigates the removal efficiency of a honeycomb electrostatic precipitator (ESP) applied to control particulate matter (PM) emissions from a small-scale boiler with combustion lignite and hard coal. The specifics of the precipitation of emissions from small-scale boilers are discussed, and the design principles for relevant ESPs are presented and used. The ion-induced nucleation of sulfuric acid occurred, causing the drastic penetration of 19 nm particles through the ESP. Despite this, the overall collection efficiency was sufficient to meet the EU’s Ecodesign Directive requirements. Back corona was not detected. The optimal ESP performance is defined with further parameters: a current density of 0.5 mA/m2 at an electric field strength of about 2.7 × 105 V/m; a minimal specific collecting area of ESP (SCA) of 60 m2/(m3/s); and Nt-product of 4.5 × 1014 s/m3. Such parameters of ESPs should ensure adequate PM emissions control for any type of boiler with similar emissions characteristics. The composition of collected fly ash particles was analysed, and a method for fly ash utilisation was proposed. This research may be helpful for designing ESPs to control PM emissions for small-scale units with fossil fuel combustion.

Atmospheric Particle Number Concentrations and New Particle Formation over the Southern Ocean and Antarctica: A Critical Review

The Southern Ocean (SO) and Antarctica play important roles in the global climate. The new particle formation (NPF) alters the availability of cloud condensation nuclei (CCN), leading to impacts on the cloud reflectance and global radiative budget. In this review, we introduce the common instruments for measuring particle number concentration (PNC) and particle number size distribution (PNSD). Based on the observations over the Antarctic and some Antarctic research stations, we explored spatial and temporal characteristics of PNCs and PNSDs. From the SO to the interior of the Antarctic, the total PNCs show a decreasing trend, and the total PNCs present an obvious seasonal cycle, with the low concentration in winter (June–August) and the high concentration in summer (December–February). By summarizing the research progress over the SO and Antarctica, we discuss possible precursors of the NPF: sulfuric acid (H2SO4, SA), methanesulfonic acid (CH3S(O)2OH, MSA), dimethyl sulfide ((CH3)2S, DMS), iodic acid (HIO3, IA), iodous acid (HIO2), ammonia (NH3), dimethylamine ((CH3)2NH, DMA), highly oxygenated organic molecules (HOMs) and other organics with low vapor pressure. We also explore several possible nucleation mechanisms: ion-induced nucleation of H2SO4 and NH3, H2SO4-amines, H2SO4-DMA-H2O, H2SO4-MSA-DMA, IA-MSA, IA-DMA, heterogeneous IA-organics nucleation mechanisms and environmental conditions required for the NPF. NPF is one of the main sources of CCN in the remote marine boundary layer, such as the SO and Antarctica. Thus, we discuss the contribution of NPF to CCN and the indirect impacts of NPF on climate. Through this review, we could better understand the PNC and NPF over the SO and Antarctica and their impacts on the global climate.

Measurement report: Increasing trend of atmospheric ion concentrations in the boreal forest

Abstract. The concentration of atmospheric ions affects the total aerosol particle number concentrations in the atmosphere as well as atmospheric new particle formation via ion-induced nucleation, ion–ion recombination, and effects on condensational growth. In this study, we investigate the concentrations and long-term trends of atmospheric ions in a boreal forest environment using 16 years of cluster ion (0.8–2 nm) and intermediate ion (2–7 nm) measurements and characterize the most important factors that explain those trends. We found that the median concentration of cluster ions in a boreal forest was 710 cm−3, the median concentration of 2–4 intermediate ions was 14 cm−3, and the median concentration of 4–7 nm intermediate ions was 9 cm−3. The concentrations of both cluster and intermediate ions have been increasing over the 16-year measurement period, with cluster ion concentrations increasing by about 1 % yr−1 and intermediate ion concentrations increasing 1.7 %–3.9 % yr−1. The increase in cluster ion concentrations can be best explained by the decrease in the coagulation sink caused by larger aerosol particles. Meanwhile, the dependence of intermediate ion concentrations on meteorological conditions is evident, but ionization sources and the coagulation sink do not seem to explain the increasing trend. This is likely because the dynamics of intermediate ions are more complicated, so that ionization sources and the coagulation sink alone cannot directly explain the variation. Season-specific analysis of the ion concentrations suggests that while the coagulation sink is the limiting factor for the ion concentrations in spring and summer, the dynamics are different in autumn and winter. Based on our findings, we recommend that a more comprehensive analysis is needed to determine if the increase in ambient ion concentrations, increasing temperature, and changing abundance of condensable vapors makes ion-mediated and ion-induced nucleation pathways in the boreal forest more relevant in the future.

Ion-Molecule Rate Constants for Reactions of Sulfuric Acid with Acetate and Nitrate Ions.

Atmospheric nucleation from precursor gases is a significant source of cloud condensation nuclei in the troposphere and thus can affect the Earth's radiative balance. Sulfuric acid, ammonia, and amines have been identified as key nucleation precursors in the atmosphere. Studies have also shown that atmospheric ions can react with sulfuric acid to form stable clusters in a process referred to as ion-induced nucleation (IIN). IIN follows similar reaction pathways as chemical ionization, which is used to detect and measure nucleation precursors via atmospheric pressure chemical ionization mass spectrometers. The rate at which ions form clusters depends on the ion-molecule rate constant. However, the rate constant varies based on the ion composition, which is often not known in the atmosphere. Previous studies have examined ion-molecule rate constants for sulfuric acid and nitrate ions but not for other atmospherically relevant ions like acetate. We report the relative rate constants of ion-molecule reactions between nitrate and acetate ions reacting with sulfuric acid. The ion-molecule rate constant for acetate and sulfuric acid is estimated to be a factor of 1.9-2.4 times higher than that of the known rate constant for nitrate and sulfuric acid. Using quantum chemistry, we find that acetate has a higher dipole moment and polarizability than nitrate. This may contribute to an increase in the collision cross-sectional area between acetate and sulfuric acid and lead to a greater reaction rate constant than nitrate. The ion-molecule rate constant for acetate with sulfuric acid will help quantify the contribution of acetate ions to atmospheric ion-induced new particle formation.

On the relation between apparent ion and total particle growth rates in the boreal forest and related chamber experiments

Abstract. The understanding of new particle formation and growth processes is critical for evaluating the role of aerosols in climate change. One of the knowledge gaps is the ion–particle interaction during the early growth process, especially in the sub-3 nm range, where direct observations are sparse. While molecular interactions would imply faster growth rates of ions compared to neutral particles, this phenomenon is not widely observed in the atmosphere. Here, we show field measurements in the boreal forest indicating a smaller apparent growth rate of the ion population compared to the total particles. We use aerosol dynamics simulations to demonstrate that this effect can be caused by the changing importance of ion-induced nucleation mechanisms during the day. We further compare these results with chamber experiments under similar conditions, where we demonstrate that this effect critically depends on the abundance of condensable vapors and the related strength of ion-induced nucleation. Our results imply that atmospheric ion growth rate measurements below 3 nm need to be evaluated very carefully as they do not represent condensational growth alone but are influenced by ion–particle population interactions.

Performance Evaluation of a Novel Pilot-Scale Wet Electrostatic Precipitator in a Bio-Drying-Assisted Solid Recovered Fuel (SRF) Generation Plant: Particulate Matter (PM) Collection Efficiency

The production of solid recovered fuel (SRF) from sewage sludge has been credited with facilitating Korea’s waste management shift toward a resource circular economy. In this study, a novel pilot-scale wet electrostatic precipitator (WESP) was developed and installed in a bio-drying-assisted solid recovered fuel (SRF) generation plant for the first time. To investigate the performance of the novel WESP, various sizes of particulate matter, i.e., total particle matter (PM), particle matter smaller than 10 μm (PM10), and particle matter smaller than 0.1 μm (PM0.1), collection efficiencies were evaluated and demonstrated promising performances. Under optimal operating conditions (flow rate of 5 m3/min and an applied voltage of 30 kV), 99.76% PM and 91% PM10 collection efficiencies were achieved, and the PM concentration was 0.16 mg/m3, which met the exhaust emission standard. However, a dramatic increase in PM0.1 was observed and could be explained by the break-up theory, binary homogenous nucleation, and ion-induced nucleation. The experimental findings could serve as useful information to understand the WESP system.

Free Energy Prediction of Ion-Induced Nucleation of Aqueous Aerosols

Ion-induced nucleation (IIN) is thought to be an important nucleation pathway of atmospheric aerosols. We present a combined polarizable molecular dynamics (MD) simulation and the classic ion-induced nucleation theory (IINT) approach to predict the free energy profiles of the ion-induced nucleation of aqueous aerosols in a qualitative or semiquantitative way. The dependence of both cluster structure and thermodynamic properties on cluster sizes and ion species is also systemically studied. It is confirmed the ions can significantly enhance the cluster stability, and thereby increase the nucleation rate. The ability of the common atmospheric ions to enhance the nucleation rate follows the order SO42- > H3O+ > NH4+ > NO3-, coinciding with the order of their solvation free energies. Therefore, the solvation energy can be employed as a rough index for evaluating the INN ability. Overall, the consistency between the present predictions and previous experimental and theoretical observations demonstrates the combination of MD simulation and the IINT appears to be a promising approach for exploring the IIN process and understanding the microscopic mechanism of atmospheric-related ions.

Organic acid-ammonia ion-induced nucleation pathways unveiled by quantum chemical calculation and kinetics modeling: A case study of 3-methyl-1,2,3-butanetricarboxylic acid

Nucleation of organic acids (OAs) and H2SO4 is an important source for new particle formation in the atmosphere. However, it is still unclear whether organic acids can produce nanoparticles independent of H2SO4. In this study, 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA) was adopted as a model of OAs. Pathways of clustering from MBTCA, ammonia and ions (NH4+ and NO3−) to form a 1.9 nm nucleus were investigated by quantum chemical calculation and kinetic modeling. Results show recombination of charged clusters/ions plays an essential role in the nucleation processes. Cluster formation rates increase by a factor of 103 when NH3 increases from 2.6 × 108 molecules·cm−3 (under clean conditions) to 2.6 × 1011 molecules·cm−3 (under polluted conditions), as NH3 can stabilize MBTCA clusters and change ion compositions from H3O+ to NH4+. Although the proposed new mechanism cannot compete with H2SO4–NH3–H2O or H2SO4-OA nucleation currently, it may be important in the future with the decline of SO2 concentration.

Theoretical study of the formation and nucleation mechanism of highly oxygenated multi-functional organic compounds produced by α-pinene.

In recent years, highly oxygenated organic molecules (HOMs) derived from photochemical reactions of α-pinene, the most abundant monoterpene, have been considered as important precursors of biogenic particles. However, the specific reactions of HOMs remain largely unknown, especially the corresponding formation and nucleation mechanism in the nanoscale. In this study, we implemented quantum chemical calculations and molecular dynamics (MD) simulations to explore the mechanism of the formation of HOM monomers/dimers by ozonolysis and autoxidation of α-pinene. Furthermore, we investigated the mechanisms of HOMs with different oxygen-to‑carbon (O/C) ratios and functional groups participating in neutral and ion-induced nucleation. The results show that the formation of HOMs is hardly affected by water, sulfuric acid and ions. In the ion-induced nucleation, HOM can dominate the initial nucleation steps; however, in the neutral nucleation, HOMs are more likely to participate in the growth stage. In addition, the nucleation ability of HOM has a bearing on the O/C ratio and the types of the functional groups. The current calculations provide valuable insight into the formation mechanism of the pure organic particles at low sulfuric acid concentrations.

Role of iodine oxoacids in atmospheric aerosol nucleation.

Iodic acid (HIO3) is known to form aerosol particles in coastal marine regions, but predicted nucleation and growth rates are lacking. Using the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber, we find that the nucleation rates of HIO3 particles are rapid, even exceeding sulfuric acid-ammonia rates under similar conditions. We also find that ion-induced nucleation involves IO3 - and the sequential addition of HIO3 and that it proceeds at the kinetic limit below +10°C. In contrast, neutral nucleation involves the repeated sequential addition of iodous acid (HIO2) followed by HIO3, showing that HIO2 plays a key stabilizing role. Freshly formed particles are composed almost entirely of HIO3, which drives rapid particle growth at the kinetic limit. Our measurements indicate that iodine oxoacid particle formation can compete with sulfuric acid in pristine regions of the atmosphere.

Ion induced nucleation based-generator of strictly singly charged (solid - liquid) polydisperse particles up to 1 μm

Abstract: Calibration of optical counters, condensation particle counters, electrical impactors, filtration efficiency measurement, heterogeneous condensation (and many other laboratory applications in aerosol science and technology) are widely used with singly charged particles classified by a differential mobility analyzer with particles smaller than 1 μm. Nevertheless the method presents an ambiguity because of the presence of multi charged large particles of the same mobility than singly ones. This ambiguity results in uncertainty in the concentration regarded as a reference. The present paper reports a generation method of strictly singly (positive and negative) charged liquid and solid particles up to 1 μm. The generation-method is based on ion-induced nucleation of singly charged atmospheric ions. The method uses evaporation and controlled condensation of liquids or solid on seed ions. The ions grow and form wide continuum polydisperse distributions of positive or negative liquid/solid polydisperse particles up to 1 μm. The ions are produced with a corona or radioactive or soft X ray or UV source in filtered dry stream air. The final formed droplets or spheres around the ions keep the positive or negative initial charge of the ions. Vapors from low meting point solids or high boiling point and low vapor pressure liquids are used in this vaporizer-condenser generator. The paper focuses on particles with diameters up to 1 μm dedicated to classical differential mobility analyzers (DMA). The results with larger particles produced with the same generator design using heterogeneous condensation of vapors on sub 10 nm singly charged particles from melting NiCr (Kanthal) wires in air will be published in a second paper (manuscript in preparation). A companion paper on the saturation ratio profiles modeling with Comsol and comparison theory-experiments is in preparation. • Polydisperse aerosol generator based on ion induced nucleation is presented and characterized in this paper. • The generator produces particles from low melting points solids or low vapor pressure liquids. • The generator is based on evaporation-condensation method used in the widely used Sinclair Lamer generators. • Atmospheric ions produced by a corona source are used as seed residues. • Singly charged spherical particles (solid or liquid) up to 1 μm are produced by the generator without neutralizer.

Determination of the collision rate coefficient between charged iodic acid clusters and iodic acid using the appearance time method

Ions enhance the formation rate of atmospheric aerosol particles, which play an important role in Earth’s radiative balance. Ion-induced nucleation involves the stepwise accretion of neutral monome...