Atmospheric Initial Nucleation Containing Carboxylic Acids

Abstract

The possible involvement of chemical components in atmospheric new particle formation has received increased attention in recent years. However, the deep understanding of the clusters formed between atmospheric gas-phase organic acids is incomplete. In this work, the chemical and physical properties of the cluster formed between three organic acids [glyoxylic acid (GA), oxalic acid (OA), and pyruvic acid (PA)] with common atmospheric nucleation precursors [methyl hydrogen sulfate (MHS), methanesulfonic acid (MSA), and hydroxymethanesulfonic acid (HMSA)] have been investigated with density functional theory and ab initio coupled-cluster singles and doubles with perturbative triples (CCSD­(T)) theory. Six- to nine-membered cyclic ring structures are mainly arranged via two classes of intermolecular hydrogen bonds: SO–H···O and CO–H···O. The GA/OA/PA–MHS/MSA/HMSA complexes with the nine- and eight-membered cyclic ring structures are thermodynamically more stable than the others. Large red shifts of the OH-stretching vibrational frequencies of both SO–H···O (354–794 cm–1) and CO–H···O (320–481 cm–1) are obtained with regard to the isolated gas monomers. Atoms in molecules topological analysis reveals that the Laplacian of the charge density of the bimolecular interactions in the GA/OA/PA–MHS/MSA/HMSA complexes is higher than the upper value of the hydrogen bond criteria. The thermodynamic data, dipole moments, and atmospheric mixing ratios indicate that the MHS- and MSA-containing complexes possibly take part in atmospheric new particle formation. Additionally, the environmental factors, such as temperature and pressure, are also important in atmospheric particle nucleation, and the gas-mixing ratios of the clusters at 12 km are much enhanced by 18–44 times with respect to the ones at the ground level. This study suggests that small cluster calculations may be helpful in simulating atmospheric new particle formation.

Study of the Interactions between MeOH and Daidzein at the Molecular Level

“…These two options have been shown to give good frequencies and thermochemical corrections to the electronic energies for the hydrogen-bonded complexes. 37 For each stationary point, frequency calculations confirmed that no imaginary frequencies existed. The binding energies (BEs) were calculated as the energy difference between the complex and the sum of the monomers.…”

“…DFT has been widely used in predicting the chemical and physical properties of biomolecules, such as coumarin, glycitein, genistein, etc. ,, Based on the results of previous studies, the DFT calculations employing the Becke three-parameter and Lee–Yang–Parr hybrid functional with the D3 version of Grimme’s dispersion (B3LYP-D3) showed a fine performance on small bimolecular and trimolecular clusters, and its predictions agree best with experiments compared to other density functionals. − For all of the DFT calculations, the cc-pVTZ basis set was used as it is a good compromise between accuracy and efficiency and does not yield significant errors in the thermal contribution to the free energy. , The additional options “opt = verytight” and “integral = ultrafine” were included in all of the optimization calculations. These two options have been shown to give good frequencies and thermochemical corrections to the electronic energies for the hydrogen-bonded complexes . For each stationary point, frequency calculations confirmed that no imaginary frequencies existed.…”

Atmospheric implication of synergy in methanesulfonic acid–base trimers: a theoretical investigation

“…25 Theoretical research shows that methyl hydrogen sulfate (MHS)-based and MSAbased trimers are more thermodynamically favorable and may participate in atmospheric NPF due to synergy between the base molecules. 26,27 To our knowledge, the effects of synergy between basic molecules on the binding energy and stability of the initial clusters involving MSA is still unclear at the molecular level, especially for MSA-base-base trimers. In this work, the hydrogen bonding, thermodynamic properties, evaporation, and atmospheric relevance of MSA-X-Y (X, Y ¼ A, M, and D) trimers have been investigated using DFT theoretical methods and ACDC kinetics simulations.…”

The Role of Organic Acids in New Particle Formation from Methanesulfonic Acid and Methylamine

“…The potentially important role of OAs in MSA-driven nucleation has been pointed out by previous studies, which focused on the interaction between MSA and several organic acid monomers or role of oxalic acid in MSA-amine NPF (Zhao et al, 2017;Arquero et al, 2017a;Arquero et al, 2017b;Xu et al, 2017;Sheng et al, 2019). However, to date, the underlying enhancing effects from a broad range of OAs on MSA-amine nucleation have not been examined.…”