Nucleation and Growth of Nanoparticles in the Atmosphere Renyi Zhang,* Alexei Khalizov, Lin Wang, Min Hu, and Wen Xu Department of Atmospheric Sciences andDepartment of Chemistry, Center for Atmospheric Chemistry and Environment, Texas A&M University, College Station, Texas 77843, United States Department of Environmental Science & Engineering and Institute of Global Environment Change Research, Fudan University, Shanghai 200433, China State Key Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China

Nucleation and Growth of Nanoparticles in the Atmosphere

This work assesses different computational strategies for predicting structures and Gibb’s free energies of reaction of atmospheric prenucleation clusters. The performance of 22 Density Functional Theory functionals in predicting equilibrium structures of molecules and water prenucleation clusters of atmospheric relevance is evaluated against experimental data using a test set of eight molecules and prenucleation clusters: SO2, H2SO4, CO2·H2O, CS2·H2O, OCS·H2O, SO2·H2O, SO3·H2O, and H2SO4·H2O. Furthermore, the functionals are tested and compared for their ability to predict the free energy of reaction for the formation of five benchmark atmospheric prenucleation clusters: H2SO4·H2O, H2SO4·(H2O)2, H2SO4·NH3, HSO4–·H2O, and HSO4–·(H2O)2. The performance is evaluated against experimental data, coupled cluster, and complete basis set extrapolation procedure methods. Our investigation shows that the utilization of the M06-2X functional with the 6-311++G(3df,3pd) basis set represents an improved approach compar...

Assessment of Density Functional Theory in Predicting Structures and Free Energies of Reaction of Atmospheric Prenucleation Clusters

Photochemical oxidation of aromatic hydrocarbons leads to tropospheric ozone and secondary organic aerosol (SOA) formation, with profound implications for air quality, human health, and climate. Toluene is the most abundant aromatic compound under urban environments, but its detailed chemical oxidation mechanism remains uncertain. From combined laboratory experiments and quantum chemical calculations, we show a toluene oxidation mechanism that is different from the one adopted in current atmospheric models. Our experimental work indicates a larger-than-expected branching ratio for cresols, but a negligible formation of ring-opening products (e.g., methylglyoxal). Quantum chemical calculations also demonstrate that cresols are much more stable than their corresponding peroxy radicals, and, for the most favorable OH (ortho) addition, the pathway of H extraction by O2 to form the cresol proceeds with a smaller barrier than O2 addition to form the peroxy radical. Our results reveal that phenolic (rather than peroxy radical) formation represents the dominant pathway for toluene oxidation, highlighting the necessity to reassess its role in ozone and SOA formation in the atmosphere.

https://www.pnas.org/content/pnas/114/31/8169.full.pdf

Reassessing the atmospheric oxidation mechanism of toluene

This work assesses the binding energies of atmospherically relevant clusters containing H2SO4, H2O, NH3 and (CH3)2NH using density functional theory. The performance of seven DFT functionals (B3LYP, CAM-B3LYP, M06-2X, PW91, LC-PW91, PBE0 and ωB97X-D) is evaluated against high level explicitly correlated coupled cluster methods using a test set of 107 atmospherically relevant clusters. Our studies show that all the tested functionals correlate well with the coupled cluster results, but with highly varying mean absolute errors. The PBE0, CAM-B3LYP, PW91 and M06-2X functionals are found to perform similarly with errors in the range of 2.53–3.46 kcal mol−1, while the B3LYP and LC-PW91 functionals yield higher errors of 6.95 kcal mol−1 and 10.66 kcal mol−1, respectively. The ωB97X-D functional gives the best estimate of the binding energies with a mean absolute error as low as 2.12 kcal mol−1 over the large test set of clusters.

Assessment of binding energies of atmospherically relevant clusters.

Dicarboxylic acids are important products from photooxidation of volatile organic compounds and are believed to play an important role in the formation and growth of atmospheric secondary organic a...

Theoretical Investigation of Interaction of Dicarboxylic Acids with Common Aerosol Nucleation Precursors

Nucleation in the Earth’s atmosphere plays a vital role in the aerosol radiative forcing associated directly with the production of ultrafine particles responsible for adverse public health impacts and global climate changes. In the present work, the interaction of the common organic oxalic acid with the atmospheric nucleation precursors and trace ionic species has been investigated using the Density Functional Theory (DFT). A comprehensive study of the hydrogen-bonded complexes of oxalic acid with neutral monomers and ionic clusters of the sulfuric acid, water and ammonia, the key atmospheric nucleation precursors, has been carried out. We found that the bonding of the oxalic acid with the above-mentioned neutrals is moderately weak, and thus, the oxalic acid cannot stabilize the binary sulfuric acid–water and ternary sulfuric acid–ammonia clusters. The interaction of the oxalic acid with positive ionic species is, in contrast, strong and significantly enhances stability of the clusters formed over the ions. The hydration of positively charged (C2H2O4)(H3O+), ( C 2 H 2 O 4 ) ( NH 4 + ) and (C2H2O4)(H3O+)(H2SO4) clusters is also strong and close to that of the sulfuric acid, the key atmospheric nucleation precursor. These considerations lead us to a logical conclusion that the oxalic acid can catalyse the production of positively charged pre-nucleation clusters and, thus, its role in nucleation of positive ions in the Earth’s troposphere should be studied in further details.

Formation and properties of hydrogen-bonded complexes of common organic oxalic acid with atmospheric nucleation precursors

Atmospheric aerosols formed via nucleation in the Earth’s atmosphere play an important role in the aerosol radiative forcing associated directly with global climate changes and public health. Although it is well-known that atmospheric aerosol particles contain organic species, the chemical nature of and physicochemical processes behind atmospheric nucleation involving organic species remain unclear. In the present work, the interaction of common organic acids with molecular weights of 122, 116, 134, 88, 136, and 150 (benzoic, maleic, malic, pyruvic, phenylacetic, and tartaric acids) with nucleation precursors and charged trace species has been investigated. We found a moderate strong effect of the organic species on the stability of neutral and charged ionic species. In most cases, the free energies of the mixed H2SO4−organic acid dimer formation are within 1−1.5 kcal mol−1 of the (H2SO4)(NH3) formation energy. The interaction of the organic acids with trace ionic species is quite strong, and the correspo...

Interaction between Common Organic Acids and Trace Nucleation Species in the Earth’s Atmosphere

New particle formation (NPF) is the major source of atmospheric aerosol particles. However, the chemical species involved and the exact mechanism are still unclear. Cycloaddition reaction of SO3 to carboxylic acids bas been identified as a possible formation mechanism of carboxylic sulfuric anhydrides which may be involved in NPF. Herein, energy profiles for forming diaterpenylic acetate sulfuric anhydride (DTASA) through cycloaddition of SO3 to diaterpenylic acid acetate (DTAA) and the potential role of DTASA in NPF were studied through computational methods combined with atmospheric cluster dynamics code (ACDC). Gas phase reaction barriers for the two carboxyl groups of DTAA are 0.4 and 0.6 kcal mol−1, respectively, illustrating a feasible formation mechanism for DTASA. According to thermodynamical analysis and dynamical simulations, atmospheric clusters containing DTASA and atmospheric nucleation precursors sulfuric acid (SA), ammonia (NH3) and dimethylamine (DMA) possess both thermodynamically and dynamically higher stabilities than those of DTAA-contained clusters. Furthermore, DTASA–NH3 and DTASA–DMA are more stable than SA–NH3 and SA–DMA, enabling DTASA, even carboxylic sulfuric anhydrides, to become potential participants in the atmospheric NPF process which may hence promote a better understanding of NPF.

https://pubs.rsc.org/en/content/articlepdf/2022/ra/d2ra00226d

Wei Wang

Papers

Formation and properties of hydrogen-bonded complexes of common organic oxalic acid with atmospheric nucleation precursors

Interaction between Common Organic Acids and Trace Nucleation Species in the Earth’s Atmosphere

A theoretical study on the formation mechanism of carboxylic sulfuric anhydride and its potential role in new particle formation