Positive matrix factorization reveals volatility-resolved composition from new particle formation during α-pinene ozonolysis

Atmospheric aerosols influence climate and human health, yet the mechanisms governing new particle formation (NPF) and early growth remain incompletely understood, in part because ultrafine particle composition and volatility are difficult to measure and interpret. Here we combine size- and temperature-resolved Thermal Desorption Chemical Ionization Mass Spectrometer measurements with positive matrix factorization (PMF) to reduce chemical complexity in particles formed during α-pinene ozonolysis in a continuous-flow chamber. PMF resolves seven factors: six parent ion-dominated factors spanning semi-volatile to low-volatility behavior with factor log C* ranging from 2.48 to -3.67, and one decomposition factor dominated by thermal and ionization fragments. Representative ions indicate a systematic volatility progression from semi-volatile carboxylic acids to low-volatility multifunctional acids and diacids. An absorptive partitioning model using size distribution-derived total particulate..., The chemical composition of particles generated from α-pinene ozonolysis was characterized by Thermal Desorption Chemical Ionization Mass Spectrometry (TDCIMS). For these experiments, the TDCIMS was operated in negative ion mode, and assigned ions were assumed to have the form [M−H]-. Particles were collected on a filament and then thermally desorbed during a linear temperature ramp to approximately 800 °C. After each particle collection, a background analysis was performed. PMF analysis was performed using EPA PMF 5.0 on the resulting background-subtracted thermograms, defined as collection intensity minus background intensity.
Each desorption thermogram consists of 350 points spanning 0–70 s. Because the PMF input matrix required a single monotonically increasing independent variable, an arbitrary sequential index was assigned to the rows of the concentration and uncertainty matrices and stored in the first column labeled time. This index was used only to preserve the ordering of poin..., # Data from: Positive matrix factorization reveals volatility-resolved composition from new particle formation during α-pinene ozonolysis

Name: James Smith

ORCID: 0000-0003-4677-8224

Institution: University of California, Irvine

Address: Rowland Hall Room 317C, Irvine, CA 92697

Email: [[e-mail]](mailto:[e-mail])

Author/Associate or Co-investigator Information

Name: Jeremy Wakeen

ORCID: 0000-0002-1452-5612

Institution: University of California, Irvine

Address: Irvine, CA 92697

Email: [[e-mail]](mailto:[e-mail])

Date of data collection: March 12, 2025

Geographic location of data collection: Irvine, CA, USA.

Information about funding sources that supported the collection of the data:

U. S. Department of Energy (DE-SC0021208)

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Licenses/restrictions placed on the data: None.

Links to publications that cite or use the data:

Wakeen, J., O’Donnell, S.E., Collins, D.R., Pierce, J. R., Smith, J. N.: Positive matrix fac..., ,