University of Oulu

Xiangrui Kong, Josip Lovrić, Sofia M. Johansson, Nønne L. Prisle, and Jan B. C. Pettersson, The Journal of Physical Chemistry A 2021 125 (28), 6263-6272, DOI: 10.1021/acs.jpca.1c02309

Dynamics and sorption kinetics of methanol monomers and clusters on nopinone surfaces

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Author: Kong, Xiangrui1; Lovrić, Josip1; Johansson, Sofia M.1;
Organizations: 1Department of Chemistry and Molecular Biology, Atmospheric Science, University of Gothenburg, Gothenburg SE-41296, Sweden
2Center for Atmospheric Research, University of Oulu, Oulu FI-90014, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 4.1 MB)
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Language: English
Published: American Chemical Society, 2021
Publish Date: 2021-08-19


Organic–organic interactions play important roles in secondary organic aerosol formation, but the interactions are complex and poorly understood. Here, we use environmental molecular beam experiments combined with molecular dynamics simulations to investigate the interactions between methanol and nopinone, as atmospheric organic proxies. In the experiments, methanol monomers and clusters are sent to collide with three types of surfaces, i.e., graphite, thin nopinone coating on graphite, and nopinone multilayer surfaces, at temperatures between 140 and 230 K. Methanol monomers are efficiently scattered from the graphite surface, whereas the scattering is substantially suppressed from nopinone surfaces. The thermal desorption from the three surfaces is similar, suggesting that all the surfaces have weak or similar influences on methanol desorption. All trapped methanol molecules completely desorb within a short experimental time scale at temperatures of 180 K and above. At lower temperatures, the desorption rate decreases, and a long experimental time scale is used to resolve the desorption, where three desorption components are identified. The fast component is beyond the experimental detection limit. The intermediate component exhibits multistep desorption character and has an activation energy of Ea = 0.18 ± 0.03 eV, in good agreement with simulation results. The slow desorption component is related to diffusion processes due to the weak temperature dependence. The molecular dynamics results show that upon collisions the methanol clusters shatter, and the shattered fragments quickly diffuse and recombine to clusters. Desorption involves a series of processes, including detaching from clusters and desorbing as monomers. At lower temperatures, methanol forms compact cluster structures while at higher temperatures, the methanol molecules form layered structures on the nopinone surface, which are visible in the simulation. Also, the simulation is used to study the liquid–liquid interaction, where the methanol clusters completely dissolve in liquid nopinone, showing ideal organic–organic mixing.

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Series: The journal of physical chemistry. A
ISSN: 1089-5639
ISSN-E: 1520-5215
ISSN-L: 1089-5639
Volume: 125
Issue: 28
Pages: 6263 - 6272
DOI: 10.1021/acs.jpca.1c02309
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
116 Chemical sciences
Funding: This work is supported by the Swedish Research Council VR (2015-04212). X.K. acknowledges the supports from the National Natural Science Foundation of China (41975160) and the Swedish Foundation for International Cooperation in Research and Higher Education (CH2019-8361). This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme, Project SURFACE (Grant Agreement No. 717022) and from the Academy of Finland (grant nos. 308238, 314175, and 335649).
EU Grant Number: (717022) SURFACE - The unexplored world of aerosol surfaces and their impacts.
Academy of Finland Grant Number: 308238
Detailed Information: 308238 (Academy of Finland Funding decision)
314175 (Academy of Finland Funding decision)
335649 (Academy of Finland Funding decision)
Copyright information: © The Authors 2021. Published under the Creative Commons Attribution 4.0 International (CC BY 4.0) license.