scholarly journals Sulfuric acid nucleation: power dependencies, variation with relative humidity, and effect of bases

2012 ◽  
Vol 12 (1) ◽  
pp. 1117-1150 ◽  
Author(s):  
J. H. Zollner ◽  
W. A. Glasoe ◽  
B. Panta ◽  
K. K. Carlson ◽  
P. H. McMurry ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Flow Reactor ◽  
Sulfuric Acid Concentration ◽  
Particle Growth ◽  
Ionization Mass ◽  
Particle Detection ◽  
Nitrogen Base ◽  
Condensation Particle Counter ◽  
Atmospheric Nucleation ◽  
New Treatment

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 H2O of ~7. The critical cluster contains about 5 H2SO4 molecules and a new treatment of the power dependency for H2O suggests about 12 H2O 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 efficiencies, sulfuric acid and nitrogen base detection, wall losses, and the extent of particle growth are discussed with the help of a recent computational fluid dynamics study that simulated the flow and chemistry in the flow reactor. Results are compared to previous laboratory nucleation studies and they are also discussed in terms of atmospheric nucleation scenarios.

scholarly journals Sulfuric acid nucleation: power dependencies, variation with relative humidity, and effect of bases

2012 ◽  
Vol 12 (10) ◽  
pp. 4399-4411 ◽  
Author(s):  
J. H. Zollner ◽  
W. A. Glasoe ◽  
B. Panta ◽  
K. K. Carlson ◽  
P. H. McMurry ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Flow Reactor ◽  
Sulfuric Acid Concentration ◽  
Particle Growth ◽  
Ionization Mass ◽  
Particle Detection ◽  
Nitrogen Base ◽  
Condensation Particle Counter ◽  
Atmospheric Nucleation ◽  
New Treatment

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 H2O of ~7. The critical cluster contains about 5 H2SO4 molecules and a new treatment of the power dependency for H2O suggests about 12 H2O 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.

scholarly journals Homogenous nucleation of sulfuric acid and water at atmospherically relevant conditions

2010 ◽  
Vol 10 (11) ◽  
pp. 25959-25989 ◽  
Author(s):  
D. Brus ◽  
K. Neitola ◽  
T. Petäjä ◽  
J. Vanhanen ◽  
A.-P. Hyvärinen ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Detection Efficiency ◽  
Sulfuric Acid Concentration ◽  
Field Measurements ◽  
Ionization Mass ◽  
Atmospheric Measurements ◽  
Flow Tube ◽  
Measured Concentration ◽  
Condensation Particle Counter ◽  
Atmospheric Nucleation

Abstract. In this study the homogeneous nucleation rates of sulfuric acid and water were measured by using a flow tube technique. The goal was to directly compare particle formation rates obtained from atmospheric measurements with nucleation rates of freshly nucleated particles measured with particle size magnifier (PSM) which has detection efficiency of unity for particles having mobility diameter of 1.5 nm. The gas phase sulfuric acid concentration in this study was measured with the chemical ionization mass spectrometer (CIMS), commonly used in field measurements. The wall losses of sulfuric acid were estimated from measured concentration profiles along the flow tube. The initial concentrations of sulfuric acid estimated from loss measurements ranged from 108 to 3×109 molecules cm−3. The nucleation rates obtained in this study cover about three orders of magnitude from 10−1 to 102 cm3 s−1 for commercial ultrafine condensation particle counter (UCPC) TSI model 3025A and from 101 to 104 cm3 s−1 for PSM. The nucleation rates and the slopes (dlnJ/dln[H2SO4]) show satisfactory agreement when compared to empirical kinetic and activation models and the latest atmospheric nucleation data.

scholarly journals Contribution of sulfuric acid and oxidized organic compounds to particle formation and growth

2012 ◽  
Vol 12 (5) ◽  
pp. 11351-11389 ◽  
Author(s):  
F. Riccobono ◽  
L. Rondo ◽  
M. Sipilä ◽  
P. Barmet ◽  
J. Curtius ◽  
...  
Keyword(s):  
Growth Rate ◽  
Sulfuric Acid ◽  
Organic Compounds ◽  
Growth Rates ◽  
Strong Dependence ◽  
Sulfuric Acid Concentration ◽  
Particle Growth ◽  
Particle Formation ◽  
Ionization Mass ◽  
Organic Vapors

Abstract. Lack of knowledge about the mechanisms underlying new particle formation and their subsequent growth is one of the main causes for the large uncertainty in estimating the radiative forcing of atmospheric aerosols in global models. We performed chamber experiments designed to study the contributions of sulfuric acid and organic vapors to formation and to the early growth of nucleated particles, respectively. Distinct experiments in the presence of two different organic precursors (1,3,5-trimethylbenzene and α-pinene) showed the ability of these compounds to reproduce the formation rates observed in the low troposphere. These results were obtained measuring the sulfuric acid concentrations with two Chemical Ionization Mass Spectrometers confirming the results of a previous study which modeled the sulfuric acid concentrations in presence of 1,3,5-trimethylbenzene. New analysis methods were applied to the data collected with a Condensation Particle Counter battery and a Scanning Mobility Particle Sizer, allowing the assessment of the size resolved growth rates of freshly nucleated particles. The effect of organic vapors on particle growth was investigated by means of the growth rate enhancement factor (Γ), defined as the ratio between the measured growth rate in the presence of α-pinene and the kinetically limited growth rate of the sulfuric acid and water system. The observed Γ values indicate that the growth is dominated by organic compounds already at particle diameters of 2 nm. Both the absolute growth rates and Γ showed a strong dependence on particle size supporting the nano-Köhler theory. Moreover, the separation of the contributions from sulfuric acid and organic compounds to particles growth reveals that the organic contribution seems to be enhanced by the sulfuric acid concentration. The size resolved growth analysis finally indicates that both condensation of oxidized organic compounds and reactive uptake contribute to particle growth.

scholarly journals Contribution of sulfuric acid and oxidized organic compounds to particle formation and growth

2012 ◽  
Vol 12 (20) ◽  
pp. 9427-9439 ◽  
Author(s):  
F. Riccobono ◽  
L. Rondo ◽  
M. Sipilä ◽  
P. Barmet ◽  
J. Curtius ◽  
...  
Keyword(s):  
Growth Rate ◽  
Sulfuric Acid ◽  
Organic Compounds ◽  
Growth Rates ◽  
Strong Dependence ◽  
Sulfuric Acid Concentration ◽  
Particle Growth ◽  
Particle Formation ◽  
Ionization Mass ◽  
Organic Vapors

Abstract. Lack of knowledge about the mechanisms underlying new particle formation and their subsequent growth is one of the main causes for the large uncertainty in estimating the radiative forcing of atmospheric aerosols in global models. We performed chamber experiments designed to study the contributions of sulfuric acid and organic vapors to the formation and early growth of nucleated particles. Distinct experiments in the presence of two different organic precursors (1,3,5-trimethylbenzene and α-pinene) showed the ability of these compounds to reproduce the formation rates observed in the low troposphere. These results were obtained measuring the sulfuric acid concentrations with two chemical ionization mass spectrometers confirming the results of a previous study which modeled the sulfuric acid concentrations in presence of 1,3,5-trimethylbenzene. New analysis methods were applied to the data collected with a condensation particle counter battery and a scanning mobility particle sizer, allowing the assessment of the size resolved growth rates of freshly nucleated particles. The effect of organic vapors on particle growth was investigated by means of the growth rate enhancement factor (Γ), defined as the ratio between the measured growth rate in the presence of α-pinene and the kinetically limited growth rate of the sulfuric acid and water system. The observed Γ values indicate that the growth is already dominated by organic compounds at particle diameters of 2 nm. Both the absolute growth rates and Γ showed a strong dependence on particle size, supporting the nano-Köhler theory. Moreover, the separation of the contributions from sulfuric acid and organic compounds to particle growth reveals that the organic contribution seems to be enhanced by the sulfuric acid concentration. Finally, the size resolved growth analysis indicates that both condensation of oxidized organic compounds and reactive uptake contribute to particle growth.

scholarly journals Chemical ionization of clusters formed from sulfuric acid and dimethylamine or diamines

2016 ◽  
Author(s):  
Coty N. Jen ◽  
Jun Zhao ◽  
Peter H. McMurry ◽  
David R. Hanson
Keyword(s):  
Sulfuric Acid ◽  
Chemical Ionization ◽  
Flow Reactor ◽  
Cluster Formation ◽  
Mass Spectrometers ◽  
Model Calculations ◽  
Molecule Reaction ◽  
Base Content ◽  
Atmospheric Nucleation ◽  
High Base

Abstract. Chemical ionization (CI) mass spectrometers are used to study atmospheric nucleation by detecting clusters produced by reactions of sulfuric acid and various basic gases. These instruments typically use nitrate to deprotonate and thus chemically ionize the clusters. In this study, we compare cluster concentrations measured using either nitrate or acetate. Clusters were formed in a flow reactor from vapors of sulfuric acid and dimethylamine, ethylene diamine, tetramethylethylene diamine, or butanediamine (also known as putrescine). These comparisons show that nitrate is unable to chemically ionize clusters with high base content. In addition, we vary the ion-molecule reaction time to probe ion processes which include proton-transfer, ion-molecule clustering, and decomposition of ions. Ion decomposition upon deprotonation by acetate/nitrate was observed. More studies are needed to quantify to what extent ion decomposition affects observed cluster content and concentrations, especially those chemically ionized with acetate since it deprotonates more types of clusters than nitrate. Model calculations of the neutral and ion cluster formation pathways are also presented to better identify the cluster types that are not efficiently deprotonated by nitrate. Comparison of model and measured clusters indicate that sulfuric acid dimer with two diamines and sulfuric acid trimer with two or more base molecules are not efficiently chemical ionized by nitrate. We conclude that acetate CI provides better information on cluster abundancies and their base content than nitrate CI.

scholarly journals Homogenous nucleation of sulfuric acid and water at close to atmospherically relevant conditions

2011 ◽  
Vol 11 (11) ◽  
pp. 5277-5287 ◽  
Author(s):  
D. Brus ◽  
K. Neitola ◽  
A.-P. Hyvärinen ◽  
T. Petäjä ◽  
J. Vanhanen ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Gas Phase ◽  
Acid Concentration ◽  
High Efficiency ◽  
Detection Efficiency ◽  
Sulfuric Acid Concentration ◽  
Ionization Mass ◽  
Atmospheric Measurements ◽  
Flow Tube ◽  
Particle Counter

Abstract. In this study the homogeneous nucleation rates in the system of sulfuric acid and water were measured by using a flow tube technique. The goal was to directly compare particle formation rates obtained from atmospheric measurements with nucleation rates of freshly nucleated particles measured with particle size magnifier (PSM) which has detection efficiency of unity for particles having mobility diameter of 1.5 nm. The gas phase sulfuric acid concentration in this study was measured with the chemical ionization mass spectrometer (CIMS), commonly used in field measurements. The wall losses of sulfuric acid were estimated from measured concentration profiles along the flow tube. The initial concentrations of sulfuric acid estimated from loss measurements ranged from 108 to 3 × 109 molecules cm−3. The nucleation rates obtained in this study cover about three orders of magnitude from 10−1 to 102 cm−3 s−1 for commercial ultrafine condensation particle counter (UCPC) TSI model 3025A and from 101 to 104 cm−3 s−1 for PSM. The nucleation rates and the slopes (dlnJ/dln [H2SO4]) show satisfactory agreement when compared to empirical kinetic and activation models and the latest atmospheric nucleation data. To the best of our knowledge, this is the first experimental work providing temperature dependent nucleation rate measurements using a high efficiency particle counter with a cut-off-size of 1.5 nm together with direct measurements of gas phase sulfuric acid concentration.

scholarly journals Chemical ionization of clusters formed from sulfuric acid and dimethylamine or diamines

2016 ◽  
Vol 16 (19) ◽  
pp. 12513-12529 ◽  
Author(s):  
Coty N. Jen ◽  
Jun Zhao ◽  
Peter H. McMurry ◽  
David R. Hanson
Keyword(s):  
Sulfuric Acid ◽  
Reaction Time ◽  
Chemical Ionization ◽  
Flow Reactor ◽  
Cluster Formation ◽  
Mass Spectrometers ◽  
Molecule Reaction ◽  
Base Content ◽  
Atmospheric Nucleation ◽  
High Base

Abstract. Chemical ionization (CI) mass spectrometers are used to study atmospheric nucleation by detecting clusters produced by reactions of sulfuric acid and various basic gases. These instruments typically use nitrate to deprotonate and thus chemically ionize the clusters. In this study, we compare cluster concentrations measured using either nitrate or acetate. Clusters were formed in a flow reactor from vapors of sulfuric acid and dimethylamine, ethylene diamine, tetramethylethylene diamine, or butanediamine (also known as putrescine). These comparisons show that nitrate is unable to chemically ionize clusters with high base content. In addition, we vary the ion–molecule reaction time to probe ion processes which include proton-transfer, ion–molecule clustering, and decomposition of ions. Ion decomposition upon deprotonation by acetate/nitrate was observed. More studies are needed to quantify to what extent ion decomposition affects observed cluster content and concentrations, especially those chemically ionized with acetate since it deprotonates more types of clusters than nitrate.Model calculations of the neutral and ion cluster formation pathways are also presented to better identify the cluster types that are not efficiently deprotonated by nitrate. Comparison of model and measured clusters indicate that sulfuric acid dimers with two diamines and sulfuric acid trimers with two or more base molecules are not efficiently chemical ionized by nitrate. We conclude that acetate CI provides better information on cluster abundancies and their base content than nitrate CI.

scholarly journals Total sulfate vs. sulfuric acid monomer concenterations in nucleation studies

2015 ◽  
Vol 15 (6) ◽  
pp. 3429-3443 ◽  
Author(s):  
K. Neitola ◽  
D. Brus ◽  
U. Makkonen ◽  
M. Sipilä ◽  
R. L. Mauldin III ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Sulfuric Acid Concentration ◽  
Monomer Concentration ◽  
Particle Growth ◽  
Production Method ◽  
Previous Method ◽  
Acid Vapor ◽  
Sulfuric Acid Production ◽  
Theoretical Predictions ◽  
Total Sulfate

Abstract. Sulfuric acid is known to be a key component for atmospheric nucleation. Precise determination of sulfuric-acid concentration is a crucial factor for prediction of nucleation rates and subsequent growth. In our study, we have noticed a substantial discrepancy between sulfuric-acid monomer concentrations and total-sulfate concentrations measured from the same source of sulfuric-acid vapor. The discrepancy of about 1–2 orders of magnitude was found with similar particle-formation rates. To investigate this discrepancy, and its effect on nucleation, a method of thermally controlled saturator filled with pure sulfuric acid (97% wt.) for production of sulfuric-acid vapor is applied and rigorously tested. The saturator provided an independent vapor-production method, compared to our previous method of the furnace (Brus et al., 2010, 2011), to find out if the discrepancy is caused by the production method itself. The saturator was used in a H2SO4–H2O nucleation experiment, using a laminar flow tube to check reproducibility of the nucleation results with the saturator method, compared to the furnace. Two independent methods of mass spectrometry and online ion chromatography were used for detecting sulfuric-acid or sulfate concentrations. Measured sulfuric-acid or total-sulfate concentrations are compared to theoretical predictions calculated using vapor pressure and a mixing law. The calculated prediction of sulfuric-acid concentrations agrees very well with the measured values when total sulfate is considered. Sulfuric-acid monomer concentration was found to be about 2 orders of magnitude lower than theoretical predictions, but with a temperature dependency similar to the predictions and the results obtained with the ion-chromatograph method. Formation rates are reproducible when compared to our previous results with both sulfuric-acid or total-sulfate detection and sulfuric-acid production methods separately, removing any doubts that the vapor-production method would cause the discrepancy. Possible reasons for the discrepancy are discussed and some suggestions include that the missing sulfuric acid is in clusters, formed with contaminants found in most laboratory experiments. One-to-two-order-of-magnitude higher sulfuric-acid concentrations (measured as total sulfate in this study) would contribute to a higher fraction of particle growth rate than assumed from the measurements by mass spectrometers (i.e. sulfuric-acid monomer). However, the observed growth rates by sulfate-containing vapor in this study does not directly imply a similar situation in the field, where sources of sulfate are much more diverse.

scholarly journals Hygroscopicity of nanoparticles produced from homogeneous nucleation in the CLOUD experiments

2016 ◽  
Vol 16 (1) ◽  
pp. 293-304 ◽  
Author(s):  
J. Kim ◽  
L. Ahlm ◽  
T. Yli-Juuti ◽  
M. Lawler ◽  
H. Keskinen ◽  
...  
Keyword(s):  
Particle Size ◽  
Sulfuric Acid ◽  
Chemical Composition ◽  
Water Uptake ◽  
Sulfuric Acid Concentration ◽  
Particle Growth ◽  
Small Mass ◽  
Initial Growth ◽  
Formation Processes ◽  
The Difference

Abstract. Sulfuric acid, amines and oxidized organics have been found to be important compounds in the nucleation and initial growth of atmospheric particles. Because of the challenges involved in determining the chemical composition of objects with very small mass, however, the properties of the freshly nucleated particles and the detailed pathways of their formation processes are still not clear. In this study, we focus on a challenging size range, i.e., particles that have grown to diameters of 10 and 15 nm following nucleation, and measure their water uptake. Water uptake is useful information for indirectly obtaining chemical composition of aerosol particles. We use a nanometer-hygroscopicity tandem differential mobility analyzer (nano-HTDMA) at subsaturated conditions (ca. 90 % relative humidity at 293 K) to measure the hygroscopicity of particles during the seventh Cosmics Leaving OUtdoor Droplets (CLOUD7) campaign performed at CERN in 2012. In CLOUD7, the hygroscopicity of nucleated nanoparticles was measured in the presence of sulfuric acid, sulfuric acid–dimethylamine, and sulfuric acid–organics derived from α-pinene oxidation. The hygroscopicity parameter κ decreased with increasing particle size, indicating decreasing acidity of particles. No clear effect of the sulfuric acid concentration on the hygroscopicity of 10 nm particles produced from sulfuric acid and dimethylamine was observed, whereas the hygroscopicity of 15 nm particles sharply decreased with decreasing sulfuric acid concentrations. In particular, when the concentration of sulfuric acid was 5.1 × 106 molecules cm−3 in the gas phase, and the dimethylamine mixing ratio was 11.8 ppt, the measured κ of 15 nm particles was 0.31 ± 0.01: close to the value reported for dimethylaminium sulfate (DMAS) (κDMAS ∼ 0.28). Furthermore, the difference in κ between sulfuric acid and sulfuric acid–imethylamine experiments increased with increasing particle size. The κ values of particles in the presence of sulfuric acid and organics were much smaller than those of particles in the presence of sulfuric acid and dimethylamine. This suggests that the organics produced from α-pinene ozonolysis play a significant role in particle growth even at 10 nm sizes.

scholarly journals Contribution from biogenic organic compounds to particle growth during the 2010 BEACHON-ROCS campaign in a Colorado temperate needleleaf forest

2015 ◽  
Vol 15 (15) ◽  
pp. 8643-8656 ◽  
Author(s):  
L. Zhou ◽  
R. Gierens ◽  
A. Sogachev ◽  
D. Mogensen ◽  
J. Ortega ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Ultrafine Particles ◽  
Cloud Condensation Nuclei ◽  
Sulfuric Acid Concentration ◽  
Rocky Mountain ◽  
Particle Growth ◽  
Reaction Rates ◽  
Oxidation Products ◽  
Growth Step ◽  
Sink Term

Abstract. New particle formation (NPF) is an important atmospheric phenomenon. During an NPF event, particles first form by nucleation and then grow further in size. The growth step is crucial because it controls the number of particles that can become cloud condensation nuclei. Among various physical and chemical processes contributing to particle growth, condensation by organic vapors has been suggested as important. In order to better understand the influence of biogenic emissions on particle growth, we carried out modeling studies of NPF events during the BEACHON-ROCS (Bio–hydro–atmosphere interactions of Energy, Aerosol, Carbon, H2O, Organics & Nitrogen – Rocky Mountain Organic Carbon Study) campaign at Manitou Experimental Forest Observatory in Colorado, USA. The site is representative of the semi-arid western USA. With the latest Criegee intermediate reaction rates implemented in the chemistry scheme, the model underestimates sulfuric acid concentration by 50 %, suggesting either missing sources of atmospheric sulfuric acid or an overestimated sink term. The results emphasize the contribution from biogenic volatile organic compound emissions to particle growth by demonstrating the effects of the oxidation products of monoterpenes and 2-Methyl-3-buten-2-ol (MBO). Monoterpene oxidation products are shown to influence the nighttime particle loadings significantly, while their concentrations are insufficient to grow the particles during the day. The growth of ultrafine particles in the daytime appears to be closely related to the OH oxidation products of MBO.

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