Studying volatility from composition, dilution, and heating measurements of secondary organic aerosols formed during <i>α</i>-pinene ozonolysis

Abstract

Abstract. Traditional yield curve analysis shows that semi-volatile organic compounds are a major component of secondary organic aerosols (SOAs). We investigated the volatility distribution of SOAs from α-pinene ozonolysis using positive electrospray ionization mass analysis and dilution- and heat-induced evaporation measurements. Laboratory chamber experiments were conducted on α-pinene ozonolysis, in the presence and absence of OH scavengers. Among these, we identified not only semi-volatile products, but also less volatile highly oxygenated molecules (HOMs) and dimers. Ozonolysis products were further exposed to OH radicals to check the effects of photochemical aging. HOMs were also formed during OH-initiated photochemical aging. Most HOMs that formed from ozonolysis and photochemical aging had 10 or fewer carbons. SOA particle evaporation after instantaneous dilution was measured at < 1 and ∼ 40 % relative humidity. The volume fraction remaining of SOAs decreased with time and the equilibration timescale was determined to be 24–46 min for SOA evaporation. The experimental results of the equilibration timescale can be explained when the mass accommodation coefficient is assumed to be 0.1, suggesting that the existence of low-volatility materials in SOAs, kinetic inhibition, or some combined effect may affect the equilibration timescale measured in this study.

Supplementary material to "Secondary organic aerosol formation from α-pinene, alkanes and oil sands related precursors in a new oxidation flow reactor"

“…As a result, a OFR fate correction for S/IVOCs is not feasible. Previous field measurements and laboratory studies demonstrated that SOA from various sources were mainly ~40%-80% L/ELVOCs and ~20%-60% S/IVOCs (Hong et al, 2017;Saha et al, 2017;D'Ambro et al, 2018;Sato et al, 2018;Saha et al, 2018). In our experiments, the low-NOx yields are significantly higher than the high-NOx yields (paper in preparation), indicating a lower volatility for SOA formed under low-NOx conditions.…”

A study of volatility by composition, heating, and dilution measurements of secondary organic aerosol from 1,3,5-trimethylbenzene

“…Data availability. All data used in this work can be found on the Figshare database (https://doi.org/10.6084/m9.figshare.10026131; Sato et al, 2019).…”

Temperature and acidity dependence of secondary organic aerosol formation from α-pinene ozonolysis with a compact chamber system

“…Chemical composition analysis of the Teflon filter samples was conducted using electrospray ionization liquidchromatography time-of-flight mass spectrometry (LC-TOF-MS) (Agilent Technologies, UK) similarly as in previous studies (Sato et al, 2018(Sato et al, , 2019 except that negative-mode was used in this study whereas positive-mode was used in those previous 150 studies. The mass calibration and lock-mass correction were conducted using G1969-85000 and G1969-85001 tuning mixtures (Agilent Technologies, UK), respectively.…”

“…where mSOA was calculated assuming SOA density of 1.34 g cm −3 (Sato et al, 2018) and equal to the arithmetic mean of the last three data of each experimental run. It was corrected for wall loss using the bulk-volume wall-loss rate, assuming a firstorder wall-loss constant which is independent of particle size and reaction time (Pathak et al, 2007b).…”

“…Again, 298 K was used as the reference temperature (T0). For compounds whose chemical structures 205 have been suggested by previous researchers, the SPARC online calculator (Hilal et al, 2003;Sato et al, 2018) was used for the derivation of their * . For other compounds, including organosulfates, the following equation from Li et al (2016) was applied:…”