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https://doi.org/10.5194/egusphere-2026-763
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/egusphere-2026-763
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
23 Feb 2026
| 23 Feb 2026
On describing particle nucleation within the Volatility Basis Set
Abstract. We describe atmospheric particle nucleation within the Volatility Basis Set (VBS) by identifying nucleating vapors (“nucleators”) with sufficiently high saturation ratios to drive nucleation under either neutral (termed nLVOC) or ion induced (cLVOC) conditions. These vapors are a subset of Ultra Low Volatility Organic Compounds (ULVOCs, with a saturation mass concentration below 3×10–9 µg m–3), which mainly arise from the oxidation of monoterpenes and other volatile hydrocarbons in the atmosphere. We determine the effective nucleator concentrations via nucleation efficiencies based on critical saturation ratios for neutral and charged processes. We apply these efficiencies to the overall volatility (concentration) distribution. The nucleator concentrations thus depend on the overall yield and volatility distribution of ULVOC species, as well as ambient temperature. Using organic vapor volatility distributions for α-pinene ozonolysis measured in the CERN CLOUD chamber, we can reproduce the experimental neutral and ion-induced nucleation rates between 223 K and 298 K, over a wide range of ULVOC concentrations and nucleation rates, spanning typical atmospheric values. For this system of oxygenated organic molecules from α-pinene, two competing effects prevail. As temperature drops from 298 K, the slowing rate of autoxidation lowers the ULVOC yield and so initially reduces the nucleation rates. However, at about 263 K, the colder temperatures reduce the volatilities sufficiently for nucleation rates to reverse course and start to increase with further decrease in temperature. This effect is most pronounced for neutral nucleation. The CLOUD measurements show this behavior and are faithfully reproduced in the VBS nucleation model.
How to cite. Donahue, N. M., Dada, L., Stolzenburg, D., Sommer, E., Simon, M., Schervish, M., DeVivo, J., Stinchfield, A., Burton, N., Bhattacharyya, N., Lopez, B., Wang, M., Scholz, W., Almeida, J., Zhao, B., Heinritzi, M., Gordon, H., Hansel, A., Curtius, J., Lehtipalo, K., El Haddad, I., Kirkby, J., Flagan, R., Kulmala, M., and Worsnop, D.: On describing particle nucleation within the Volatility Basis Set, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2026-763, 2026.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Atmospheric Chemistry and Physics. The peer-review process was guided by an independent editor, and the authors also have no other competing interests to declare.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.Download & links
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Status: closed
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor
| : Report abuse
- RC1: 'Comment on egusphere-2026-763', Anonymous Referee #1, 27 Mar 2026
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RC2: 'Comment on egusphere-2026-763', Anonymous Referee #2, 21 Apr 2026
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2026/egusphere-2026-763/egusphere-2026-763-RC2-supplement.pdf
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AC1: 'Comment on egusphere-2026-763', Neil M. Donahue, 12 May 2026
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2026/egusphere-2026-763/egusphere-2026-763-AC1-supplement.pdf
Status: closed
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor
| : Report abuse
-
RC1: 'Comment on egusphere-2026-763', Anonymous Referee #1, 27 Mar 2026
Donahue et al. present a very interesting and detailed study on how nucleation can be described within the previously established volatility basis set (VBS). In a first part, the thermodynamic principles of nucleation are introduced alongside a description of the VBS and subsequently extended to the nucleation of organic vapors. In the second part, the application of the VBS to nucleation is discussed in a general manner and applied in the following to previously published results from chamber nucleation experiments. The paper is well-written and follows a clear flow and logic. The presented method allows a more detailed investigation of the contribution of organic vapors to nucleation and might have substantial impact in the field.
I have some minor comments and suggestion to consider prior to publication.
- Caption Figure 1. The two panels are described as ‘a)’ and ‘b)’ which is not detailed on the plots.
- l. 107 The term ‘aerosol-phase activity’ is used here to explain decreased tendency of organic vapors to condense on very small particles, but is not well defined in this context. As I understand the reduced interaction with the particle surface due to the contribution of the particle curvature is the reason for this tendency, I suggest a brief introduction of the activity term.
- l. 147 The temperature dependency is introduced very briefly here, although it is the basis for large sections of the conclusions in this paper. I understand that this was largely introduced in the cited studies, but I would suggest adding a few more points on the assumptions necessary and maybe limitations of this approach. This might help to judge the robustness of the derived conclusions.
- l. 152 Here, the authors link nucleation with the saturation ratio of a mixture based on the VBS. The assumption being, that the formation of a cluster is driven by volatility alone and detailed chemical structure is statistically similar enough across the mixture of vapors. In section 3.3, the authors introduce a gain to describe nucleation efficiency, motivating it in part with different functional groups and the resulting different bonding situation. Is the chemical nature of a mixture and its influence on nucleation something that could be parametrized using the approach presented in this manuscript if enough comparable experimental datasets would be available?
- l. 231 should read ‘sensitive to the chemical identity’
- l. 368 the minimum is could as well be outside this window, above 278 K or below 263 K, right?
- More to that point, the measurements seem to have large uncertainties. Did the authors attempt to apply the temperature dependence to estimate the nucleation rate from the chemical composition experiments at another temperature? I understand this might inflate the manuscript too much, but maybe an example case could help to understand how different the chemical composition actually contributes to the nucleation rate.
Citation: https://doi.org/10.5194/egusphere-2026-763-RC1 -
RC2: 'Comment on egusphere-2026-763', Anonymous Referee #2, 21 Apr 2026
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2026/egusphere-2026-763/egusphere-2026-763-RC2-supplement.pdf
-
AC1: 'Comment on egusphere-2026-763', Neil M. Donahue, 12 May 2026
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2026/egusphere-2026-763/egusphere-2026-763-AC1-supplement.pdf
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Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, PA, USA
Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
Lubna Dada
Center for Energy and Environmental Sciences, Paul Scherrer Institute, 5232 Villigen, Switzerland
Dominik Stolzenburg
Institute of Materials Chemistry, TU Wien, Vienna, Austria
Eva Sommer
Faculty of Physics, University of Vienna, Wien, Austria
CERN, the European Organization for Nuclear Research, Geneve 23 CH-1211, Switzerland
Mario Simon
Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
Meredith Schervish
Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, Texas, USA
Jenna DeVivo
Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, PA, USA
Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
Alexandra Stinchfield
Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, PA, USA
Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
Natalie Burton
Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, PA, USA
Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
Nirvan Bhattacharyya
Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, PA, USA
Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
Brandon Lopez
Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, PA, USA
Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
Mingyi Wang
Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA
Wiebke Scholz
Ion Molecule Reactions & Environmental Physics Group Institute of Ion Physics and Applied Physics Leopold-Franzens University, Innsbruck Technikerstraße 25 A-6020 Innsbruck Austria
Joao Almeida
Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China
State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing, China
Martin Heinritzi
Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
Hamish Gordon
Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, PA, USA
Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
Armin Hansel
Ion Molecule Reactions & Environmental Physics Group Institute of Ion Physics and Applied Physics Leopold-Franzens University, Innsbruck Technikerstraße 25 A-6020 Innsbruck Austria
Joachim Curtius
Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
Katrianne Lehtipalo
Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland
Finnish Meteorological Institute, 00560 Helsinki, Finland
Imad El Haddad
Center for Energy and Environmental Sciences, Paul Scherrer Institute, 5232 Villigen, Switzerland
Jasper Kirkby
CERN, the European Organization for Nuclear Research, Geneve 23 CH-1211, Switzerland
Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
Richard Flagan
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
Markku Kulmala
Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland
Douglas Worsnop
Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland
Aerodyne Inc, Billerica MA, USA
Short summary
A new theory has the potential to accurately describe changes to atmospheric particle formation from the pre-industrial to the present and onwards along socioeconomic pathways addressing air pollution and climate. The model places organic nucleation in the context of the Volatility Basis Set and reveals a competition between chemistry, which accelerates as temperature rises, and vapor pressure, which drops as temperature decreases. The model reproduces observations from the CERN CLOUD chamber.
A new theory has the potential to accurately describe changes to atmospheric particle formation...
Donahue et al. present a very interesting and detailed study on how nucleation can be described within the previously established volatility basis set (VBS). In a first part, the thermodynamic principles of nucleation are introduced alongside a description of the VBS and subsequently extended to the nucleation of organic vapors. In the second part, the application of the VBS to nucleation is discussed in a general manner and applied in the following to previously published results from chamber nucleation experiments. The paper is well-written and follows a clear flow and logic. The presented method allows a more detailed investigation of the contribution of organic vapors to nucleation and might have substantial impact in the field.
I have some minor comments and suggestion to consider prior to publication.