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 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 The charging of neutral dimethylamine and dimethylamine–sulfuric acid clusters using protonated acetone

2015 ◽  
Vol 8 (6) ◽  
pp. 2577-2588
Author(s):  
K. Ruusuvuori ◽  
P. Hietala ◽  
O. Kupiainen-Määttä ◽  
T. Jokinen ◽  
H. Junninen ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Chemical Ionization ◽  
Lower Troposphere ◽  
Particle Formation ◽  
Atmospheric Conditions ◽  
Atmospheric Particle ◽  
Organic Bases ◽  
Atmospheric Nucleation ◽  
Quantum Chemical Methods ◽  
Vapour Concentration

Abstract. Sulfuric acid is generally considered one of the most important substances taking part in atmospheric particle formation. However, in typical atmospheric conditions in the lower troposphere, sulfuric acid and water alone are unable to form particles. It has been suggested that strong bases may stabilize sulfuric acid clusters so that particle formation may occur. More to the point, amines – strong organic bases – have become the subject of interest as possible cause for such stabilization. To probe whether amines play a role in atmospheric nucleation, we need to be able to measure accurately the gas-phase amine vapour concentration. Such measurements often include charging the neutral molecules and molecular clusters in the sample. Since amines are bases, the charging process should introduce a positive charge. This can be achieved by, for example, using chemical ionization with a positively charged reagent with a suitable proton affinity. In our study, we have used quantum chemical methods combined with a cluster dynamics code to study the use of acetone as a reagent ion in chemical ionization and compared the results with measurements performed with a chemical ionization atmospheric pressure interface time-of-flight mass spectrometer (CI-APi-TOF). The computational results indicate that protonated acetone is an effective reagent in chemical ionization. However, in the experiments the reagent ions were not depleted at the predicted dimethylamine concentrations, indicating that either the modelling scheme or the experimental results – or both – contain unidentified sources of error.

scholarly journals Measurement of iodine species and sulfuric acid using bromide chemical ionization mass spectrometers

2020 ◽  
Author(s):  
Mingyi Wang ◽  
Xu-Cheng He ◽  
Henning Finkenzeller ◽  
Siddharth Iyer ◽  
Dexian Chen ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Chemical Ionization ◽  
Detection Limits ◽  
Particle Formation ◽  
Cloud Chamber ◽  
Ionization Mass ◽  
New Particle Formation ◽  
Reduced Pressure ◽  
Mass Spectrometers ◽  
Iodine Species

Abstract. Iodine species are important in the marine atmosphere for oxidation and new-particle formation. Understanding iodine chemistry and iodine new-particle formation requires high time resolution, high sensitivity, and simultaneous measurements of many iodine species. Here, we describe the application of bromide chemical ionization mass spectrometers (Br-CIMS) to this task. During iodine new-particle formation experiments in the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber, we have measured gas-phase iodine species and sulfuric acid using two Br-CIMS, one coupled to a Multi-scheme chemical IONization inlet (Br-MION-CIMS) and the other to a Filter Inlet for Gasses and AEROsols inlet (Br-FIGAERO-CIMS). From offline calibrations and inter-comparisons with other instruments attached to the CLOUD chamber, we have quantified the sensitivities of the Br-MION-CIMS to HOI, I2, and H2SO4 and obtain detection limits of 5.8 × 106, 6.3 × 105, and 2.0 × 105 molec cm−3, respectively, for a 2-min integration time. From binding energy calculations, we estimate the detection limit for HIO3 to be 1.2 × 105 molec cm−3, based on an assumption of maximum sensitivity. Detection limits in the Br-FIGAERO-CIMS are around one order of magnitude higher than those in the Br-MION-CIMS; for example, the detection limits for HOI and HIO3 are 3.3 × 107 and 5.1 × 106 molec cm−3, respectively. Our comparisons of the performance of the MION inlet and the FIGAERO inlet show that bromide chemical ionization mass spectrometers using either atmospheric pressure or reduced pressure interfaces are well-matched to measuring iodine species and sulfuric acid in marine environments.

scholarly journals Measurement of iodine species and sulfuric acid using bromide chemical ionization mass spectrometers

2021 ◽  
Vol 14 (6) ◽  
pp. 4187-4202
Author(s):  
Mingyi Wang ◽  
Xu-Cheng He ◽  
Henning Finkenzeller ◽  
Siddharth Iyer ◽  
Dexian Chen ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Chemical Ionization ◽  
Detection Limits ◽  
Particle Formation ◽  
High Time Resolution ◽  
Ionization Mass ◽  
New Particle Formation ◽  
Reduced Pressure ◽  
Mass Spectrometers ◽  
Iodine Species

Abstract. Iodine species are important in the marine atmosphere for oxidation and new-particle formation. Understanding iodine chemistry and iodine new-particle formation requires high time resolution, high sensitivity, and simultaneous measurements of many iodine species. Here, we describe the application of a bromide chemical ionization mass spectrometer (Br-CIMS) to this task. During the iodine oxidation experiments in the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber, we have measured gas-phase iodine species and sulfuric acid using two Br-CIMS, one coupled to a Multi-scheme chemical IONization inlet (Br-MION-CIMS) and the other to a Filter Inlet for Gasses and AEROsols inlet (Br-FIGAERO-CIMS). From offline calibrations and intercomparisons with other instruments, we have quantified the sensitivities of the Br-MION-CIMS to HOI, I2, and H2SO4 and obtained detection limits of 5.8 × 106, 3.8 × 105, and 2.0 × 105 molec. cm−3, respectively, for a 2 min integration time. From binding energy calculations, we estimate the detection limit for HIO3 to be 1.2 × 105 molec. cm−3, based on an assumption of maximum sensitivity. Detection limits in the Br-FIGAERO-CIMS are around 1 order of magnitude higher than those in the Br-MION-CIMS; for example, the detection limits for HOI and HIO3 are 3.3 × 107 and 5.1 × 106 molec. cm−3, respectively. Our comparisons of the performance of the MION inlet and the FIGAERO inlet show that bromide chemical ionization mass spectrometers using either atmospheric pressure or reduced pressure interfaces are well-matched to measuring iodine species and sulfuric acid in marine environments.

scholarly journals Constraining the sensitivity of iodide adduct chemical ionization mass spectrometry to multifunctional organic molecules using the collision limit and thermodynamic stability of iodide ion adducts

2016 ◽  
Vol 9 (4) ◽  
pp. 1505-1512 ◽  
Author(s):  
Felipe D. Lopez-Hilfiker ◽  
Siddarth Iyer ◽  
Claudia Mohr ◽  
Ben H. Lee ◽  
Emma L. D'Ambro ◽  
...  
Keyword(s):  
Reaction Time ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Organic Molecules ◽  
Transmission Efficiency ◽  
Molecular Ions ◽  
Ionization Mass ◽  
Aerosol Composition ◽  
Molecule Reaction ◽  
Scanning Procedure

Abstract. The sensitivity of a chemical ionization mass spectrometer (ions formed per number density of analytes) is fundamentally limited by the collision frequency between reagent ions and analytes, known as the collision limit, the ion–molecule reaction time, and the transmission efficiency of product ions to the detector. We use the response of a time-of-flight chemical ionization mass spectrometer (ToF-CIMS) to N2O5, known to react with iodide at the collision limit, to constrain the combined effects of ion–molecule reaction time, which is strongly influenced by mixing and ion losses in the ion–molecule reaction drift tube. A mass spectrometric voltage scanning procedure elucidates the relative binding energies of the ion adducts, which influence the transmission efficiency of molecular ions through the electric fields within the vacuum chamber. Together, this information provides a critical constraint on the sensitivity of a ToF-CIMS towards a wide suite of routinely detected multifunctional organic molecules for which no calibration standards exist. We describe the scanning procedure and collision limit determination, and we show results from the application of these constraints to the measurement of organic aerosol composition at two different field locations.

a-pinene autoxidation at sub-second time-scales

2020 ◽  
Author(s):  
Matti Rissanen ◽  
Shawon Barua ◽  
Jordan Krechmer ◽  
Theo Kurtén ◽  
Siddharth Iyer
Keyword(s):  
Reaction Time ◽  
Organic Compounds ◽  
Time Scales ◽  
Chemical Ionization ◽  
Flow Reactor ◽  
Secondary Organic Aerosol ◽  
Computational Study ◽  
Peroxy Radical ◽  
Organic Aerosol ◽  
Ionization Mass

<p>Atmospheric aerosols impact climate and health. Most of the smallest atmospheric nanoparticles are formed by oxidation of volatile organic compounds (VOC) and subsequent condensation of resulting low-volatile vapors. Biogenic terpenes are the largest atmospheric secondary organic aerosol (SOA) source, and among these, a-pinene likely the single most important compound.</p><p> Recently, autoxidation changed the paradigm of long processing time-scales in the formation of SOA [1, 2]. Previous experiments with cyclic unsaturated compounds have indicated the autoxidation to be very rapid, forming compounds with even 10 O-atoms infused to the carbon structure in a few seconds timeframe [3-6]. Berndt et al. noted that the whole process was apparently finished already at about 1.5 seconds reaction time in cyclohexene ozonolysis initiated autoxidation, indicated by the “frozen” peroxy radical product distribution beyond this reaction time [4].</p><p>Here we performed sub-second time-scale flow reactor experiments of a-pinene ozonolysis initiated autoxidation under ambient atmospheric conditions to constrain the timeframe needed to form the first highly-oxidized reaction products, and to inspect the peroxy radical dynamics at significantly shorter reaction times than have been previously possible. The shortest achievable reaction time was around 0.1 seconds and was enabled by the new Multi-scheme chemical IONization (MION) inlet setup [7]. Nitrate and bromide were used as reagent ions in this work.</p><p> </p><p><strong>References:</strong></p><ol><li>J. D. Crounse, et al. Autoxidation of Organic Compounds in the Atmosphere, J. Phys. Chem. Lett., 2013, 4, 3513-3520.</li> <li>M. Ehn, et al. A large source of low-volatility secondary organic aerosol, Nature, 2014, 506, 476-479.</li> <li>M. P. Rissanen, et al. The formation of highly oxidized multifunctional products in the ozonolysis of cyclohexene, J. Am. Chem. Soc., 2014, 136, 15596-15606.</li> <li>T. Berndt, et al. Gas-Phase Ozonolysis of Cycloalkenes: Formation of Highly Oxidized RO<sub>2</sub> Radicals and Their Reactions with NO, NO<sub>2</sub>, SO<sub>2</sub>, and Other RO<sub>2</sub> Radicals, J. Phys. Chem. A, 2015, 119, 10336-10348.</li> <li>M. P. Rissanen, et al. Kulmala, Effects of Chemical Complexity on the Autoxidation Mechanisms of Endocyclic Alkene Ozonolysis Products: From Methylcyclohexenes toward Understanding α-Pinene, J. Phys. Chem. A, 2015, 119, 4633-4650.</li> <li>T. Kurtén, et al. Computational Study of Hydrogen Shifts and Ring-Opening Mechanisms in α-Pinene Ozonolysis Products, J. Phys. Chem. A, 2015, 119, 11366-11375.</li> <li>M. P. Rissanen, et al. Multi-scheme chemical ionization inlet (MION) for fast switching of reagent ion chemistry in atmospheric pressure chemical ionization mass spectrometry (CIMS) applications, Atmos. Meas. Tech., 2019, 12, 6635-6646.</li> </ol>

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 Constraining the sensitivity of iodide adduct chemical ionization mass spectrometry to multifunctional organic molecules using the collision limit and thermodynamic stability of iodide ion adducts

2015 ◽  
Vol 8 (10) ◽  
pp. 10875-10896 ◽  
Author(s):  
F. D. Lopez-Hilfiker ◽  
S. Iyer ◽  
C. Mohr ◽  
B. H. Lee ◽  
E. L. D'Ambro ◽  
...  
Keyword(s):  
Reaction Time ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Organic Molecules ◽  
Transmission Efficiency ◽  
Molecular Ions ◽  
Ionization Mass ◽  
Aerosol Composition ◽  
Molecule Reaction ◽  
Scanning Procedure

Abstract. The sensitivity of a chemical ionization mass spectrometer (ions formed per number density of analyte) is fundamentally limited by the collision frequency between reagent ions and analyte, known as the collision limit, the ion-molecule reaction time, and the transmission efficiency of product ions to the detector. We use the response of a time-of-flight chemical ionization mass spectrometer (ToF-CIMS) to N2O5, known to react with iodide at the collision limit, to constrain the combined effects of ion-molecule reaction time, which is strongly influenced by mixing and ion losses in the ion-molecule reaction drift tube. A mass spectrometric voltage scanning procedure elucidates the relative binding energies of the ion adducts, which influence the transmission efficiency of molecular ions through the electric fields within the vacuum chamber. Together, this information provides a critical constraint on the sensitivity of a ToF-CIMS towards a wide suite of routinely detected multifunctional organic molecules for which no calibration standards exist. We describe the scanning procedure, collision limit determination, and show results from the application of these constraints to the measurement of organic aerosol composition at two different field locations.

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.

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