Particle formation rate is one of the key factors to study the physical properties of aerosols, because it is still not entirely clear how particles form under different environmental conditions. By developing powerful and simple particle formation rate models, we can predict how many atmospheric particles are produced, and compare it with the real-time measurement to help with the scientists on discovering more hidden particle formation mechanisms.

Metal nanoparticles (Au, Pt, Cu and Ni) were generated in the aerosol phase using spark ablation and analysed for size, shape and number concentration. Particles as small as 1 nm and up to > 60 nm show shapes from fully spherical to fractal-like as characterized by electron microscopy. Furthermore, the metal particles were mixed with TiO₂ nanoparticles and the number and size of metal particles coating the TiO₂ were determined.

We present continuous ice-nucleating particle data that were measured in the Alaskan Arctic from Oct. 2021 to Dec. 2023. We found a greater efficiency in the arctic immersion freezing during autumn compared to those found previously at two mid-latitude sites, as well as profound freezing efficiencies in spring, presumably due to arctic haze events. Our study will be useful to improve atmospheric models to simulate cloud feedback and determine their impact on the global radiative energy budget.

This study examines the deliquescence behavior of NaCl particles in a turbulent humidity field using the wind tunnel LACIS-T. The results show turbulent relative humidity (RH) fluctuations affect the number of deliquesced particles, depending on mean RH, strength of humidity fluctuations, and particle residence time. It turns out that, in addition to the mean RH, it is essential to consider humidity fluctuations and particle history when determining the phase state of the deliquescent particles.

Acyl peroxy radicals can act as atmospheric oxidants of unsaturated hydrocarbons if their 1) unimolecular reactions are slow and 2) bimolecular accretion reactions are fast. Using theoretical tools, we show which acyl peroxy radicals should be considered as oxidants in the atmosphere.

We investigated the sources of ultrafine particles (UFPs) in Payerne, Switzerland, highlighting the significant role of secondary processes in elevating UFP concentrations to levels comparable to urban areas. As the first study in rural midland Switzerland to analyze new particle formation events and secondary contributions, it offers key insights for air quality regulation in Switzerland and central Europe.

Quantification of autoxidation chemistry is a complex task, essential to our understanding of atmospheric secondary aerosol formation and its impact on climate. In this work, we introduce the autoCONSTRAINT module, a semi-empirical method to deduce reaction rate coefficients for lumped autoxidation chemistry schemes based on experimental data. The theoretical approach is analytical and provides mathematically correct, though non-unique, solutions with low computational cost.

This study examines how sampling frequency influences the accuracy of low-cost particulate matter (PM) sensors. It finds that high sampling rates (15 seconds) are vital for detecting short pollution spikes like vehicle emissions, while lower rates (1 hour) are enough for tracking long-term trends. Conducted in real-world outdoor conditions, the research offers practical guidance to balance energy use and data accuracy, supporting scalable, cost-effective air quality monitoring solutions.

We report a substantial build-up of reactive molecules by sunlight in organic particulate matter causing adverse health effects. Metals naturally or by traffic emitted can complex with organic materials and initiate photochemical processes. At low humidity organic particles may become highly viscous, which lets the accumulate reactive species. We found that copper acts as an reducing species to remove some of the harmful species in the particles.

The study explores the formation of small soot clusters by precursor molecules at high temperature. Higher temperature speeds up the decomposition of gas molecules, accelerating the formation of cyclic structures decorated by aliphatic chains. This research offers new insights into the early steps of soot formation, which could help develop more informed kinetic models for pyrolysis and combustion processes.

Using quantum chemical methods we studied the uptake of first generation oxidation products onto freshly nucleated particles (FNPs). We find that pinic acid can condense on these small FNPs at realistic atmospheric conditions, thereby contributing to the early particle growth. The mechanism involves two pinic acid molecules interacting with each other, showing that direct organic-organic interactions during co-condensation onto the particle contributes to the growth.