Heterogeneous Nucleation of Butanol on NaCl: A Computational Study of Temperature, Humidity, Seed Charge, and Seed Size Effects

Abstract

Using a combination of quantum chemistry and cluster size distribution dynamics, we study the heterogeneous nucleation of n -butanol and water onto sodium chloride (NaCl) 10 seeds at different butanol saturation ratios and relative humidities. We also investigate how the heterogeneous nucleation of butanol is affected by the seed size through comparing (NaCl) 5 , (NaCl) 10 , and (NaCl) 25 seeds and by seed electrical charge through comparing (Na 10 Cl 9 ) + , (NaCl) 10 , and (Na 9 Cl 10 ) − seeds. Butanol is a common working fluid for condensation particle counters used in atmospheric aerosol studies, and NaCl seeds are frequently used for calibration purposes and as model systems, for example, sea spray aerosol. In general, our simulations reproduce the experimentally observed trends for the NaCl–BuOH–H 2 O system, such as the increase of nucleation rate with relative humidity and with temperature (at constant supersaturation of butanol). Our results also provide molecular-level insights into the vapor–seed interactions driving the first steps of the heterogeneous nucleation process. The main purpose of this work is to show that theoretical studies can provide molecular understanding of initial steps of heterogeneous nucleation and that it is possible to find cost-effective yet accurate-enough combinations of methods for configurational sampling and energy evaluation to successfully model heterogeneous nucleation of multicomponent systems. In the future, we anticipate that such simulations can also be extended to chemically more complex seeds.

Virtual Issue on Atmospheric Aerosol Research

“…New particles are generally formed via nucleation, a process in which individual molecules interact with one another until a critical cluster size is reached and particle nucleation becomes favorable . Photoassisted particle formation can be important in many cases, while heterogeneous processes can also be key drivers, as shown in detailed quantum chemical cluster calculations . Molecular precursors for new particle formation and secondary organic aerosol particles can involve the formation of highly oxygenated organic molecules from the oxidation of biogenic terpenes such as α-pinene, and the development of chemical mechanisms to describe this process is critical for climate predictions .…”

“…2 Photoassisted particle formation can be important in many cases, 3 while heterogeneous processes can also be key drivers, as shown in detailed quantum chemical cluster calculations. 4 Molecular precursors for new particle formation and secondary organic aerosol particles can involve the formation of highly oxygenated organic molecules from the oxidation of biogenic terpenes such as α-pinene, and the development of chemical mechanisms to describe this process is critical for climate predictions. 5 The energetics of peroxide formation from α-pinene were evaluated via conformational sampling using density functional theory.…”

Anticorrosive Copper Current Collector Passivated by Self‐Assembled Porous Membrane for Highly Stable Lithium Metal Batteries

“…Moreover, the average granular size is ever-incresing with the amount of deposited Li metal increases (Figure 4d-f; Figure S7c,d employed to account qualitatively for the difference on morphology. For heterogeneous nucleation (molecules/atoms adsorbed on the surface of solid impurities to form crystal nuclei, [34] such as for Li deposited on Cu substrate), the Gibbs free energy of nucleation (ΔG n ) can be expressed as (assumed the new solid phase was sphere of radius r):…”

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

“…Several studies show that QC can be utilized to evaluate thermodynamic properties of charged molecular clusters. − However, accurate QC calculations have a high computational cost which constrains their applicability to only small strongly binding molecular clusters. In our previous work, we showed that configurational sampling (CS) only up to a semiempirical level of theory is computationally effective even for large molecular clusters compared to the density functional theory (DFT) or other QC level schemes. Additionally, this method was found to produce similar cluster geometries and qualitatively similar free energy trends compared to those obtained with a combination of density functional theory (DFT, LC-ωHPBE/def2TZVP) with single-point electronic energy at a coupled cluster level (DLPNO–CCSD­(T)/aug-cc-pVTZ) .…”

“…In our previous work, we showed that configurational sampling (CS) only up to a semiempirical level of theory is computationally effective even for large molecular clusters compared to the density functional theory (DFT) or other QC level schemes. Additionally, this method was found to produce similar cluster geometries and qualitatively similar free energy trends compared to those obtained with a combination of density functional theory (DFT, LC-ωHPBE/def2TZVP) with single-point electronic energy at a coupled cluster level (DLPNO–CCSD­(T)/aug-cc-pVTZ) . Therefore, in this work, we use this semiempirical level of theory to examine clusters containing even several tens of molecules, which allows us to reveal the molecular mechanism behind the ion-induced nucleation of the studied systems.…”