Relative abundance of new particles competing against the growth of preexisting particles during isoprene ozonolysis
Year: 2025
Type: article
Abstract: Oligomeric hydroperoxides, including stabilized Criegee intermediates generated during isoprene ozonolysis, play an important role in new particle formation (NPF). In this study, we experimentally determined the relative abundance ( Φ NPF ) of new particles formed during isoprene ozonolysis, competing against the growth of preexisting particles. The number concentration of newly formed particles ( N NPF ) during isoprene ozonolysis was derived by comparing the size distribution of secondary organic aerosols (SOAs) in the presence of seed particles with that under humid conditions (relative humidity (RH) > 20%) at the same reaction time. The number concentration of particles that took up semi-volatile organic compounds ( N uptake ) was estimated from the difference in the size distribution between particle wall loss (PWL)-considered seed particles and SOAs with seed particles under humid conditions. The Φ NPF was then calculated using the formula: N NPF /( N NPF + N uptake ) under different conditions. The methodology to determine the N NPF was generally successful, whereas the determination of N uptake was complicated due to the instability of PWL in the small Teflon bag experiments. The Φ NPF can be represented as a product of the r NPF (RH), the relative abundance of new particles formed during isoprene ozonolysis as a function of RH, and the ϕ NPF (dry), the Φ NPF value obtained under dry conditions. The obtained r NPF (RH) values suggested that NPF can occur only under very limited RH conditions (RH < 10%) of isoprene ozonolysis in the atmosphere, but the products from the reaction of isoprene with O 3 , probably Criegee intermediate oligomerization products, were found mainly to contribute to NPF.
Source: Journal of Atmospheric Chemistry
Authors: Satoshi Inomata, Jun Hirokawa
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,090
OpenAlex ID: W4413791958