Publications by authors named "J Dommen"
Article Synopsis
- Aerosols from gas-to-particle processes significantly contribute to urban smog and haze, particularly through the formation of ammonium nitrate, which can thrive in polluted city conditions.
- Urban areas face complex variations in temperature and gas concentrations, influencing how quickly aerosols can form and grow.
- Experimental results from CERN's CLOUD chamber reveal that rapid temperature fluctuations can enhance nanoparticle growth, highlighting the influence of inconsistent ammonia emissions in cities on aerosol dynamics.
Biogenic vapors form new particles in the atmosphere, affecting global climate. The contributions of monoterpenes and isoprene to new particle formation (NPF) have been extensively studied. However, sesquiterpenes have received little attention despite a potentially important role due to their high molecular weight.
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- The interaction between nitrogen monoxide (NO) and organic peroxy radicals (RO) is crucial for creating highly oxygenated organic molecules (HOM), which are essential for forming secondary organic aerosols.
- New experiments show that low levels of NO (0 - 82 pptv) can actually boost HOM production by affecting RO loss and promoting alkoxy radical formation, which continues to react and form more HOM.
- These findings reveal that HOM yields in boreal forest emissions can range from 2.5%-6.5%, and high NO levels do not completely stop HOM formation, challenging previous beliefs about NO's role in lowering HOM yields, especially in environments with low NO.
OH scavengers are extensively used in studies of secondary organic aerosol (SOA) because they create an idealized environment where only a single oxidation pathway is occurring. Here, we present a detailed molecular characterization of SOA produced from α-pinene + O with a variety of OH scavengers using the extractive electrospray time-of-flight mass spectrometer in our atmospheric simulation chamber, which is complemented by characterizing the gas phase composition in flow reactor experiments. Under our experimental conditions, radical chemistry largely controls the composition of SOA.
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- New particle formation events occur frequently in polluted environments, despite high loss rates of tiny clusters, suggesting scavenging by larger particles or unknown growth mechanisms might be less effective than anticipated.
- Experiments in the CLOUD chamber at CERN showed that the creation of new particles from human-made vapors significantly drops when there are many pre-existing particles, proving they effectively scavenge smaller molecular clusters.
- In conditions with high levels of nitric acid and ammonia, newly formed particles can grow rapidly and maintain their numbers, even in heavily polluted air, which helps explain why these particles survive in haze-like situations.