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.

Ensuring that all measuring instruments deliver reliable results is an important task. For aerosol measurement, a health-related parameter is not yet well defined worldwide. We have therefore developed a test bench to evaluate and compare instruments on this key parameter. Based on the success of an initial comparison with our instruments, we underline the feasibility of a standardized test and offer a framework for improving accuracy and consistency of aerosol size distribution assessments.

Aerosol formation is an important process for our global climate. However, there are large uncertainties associated with the formation of new aerosol particles. We present quantum chemical calculations of large atmospheric molecular cluster composed of sulfuric acid (SA), ammonia (AM) and dimethyl amine (DMA). We find that mixed SA-AM-DMA clusters more efficiently for freshly nucleated particles compared to the pure SA-AM and SA-DMA systems.

Aersols, are important in many parts of industries and research. To learn more about aerosols, especially when containing nanoparticles, the here presented Centrifugal Differential Mobility Anlayser (CDMA) allows to measure the mobility equivalent diameter and the Stokes equivalent diameter at the same time. The result is a two-dimensional property distribution that provides deeper information about the entire particle collective than the isolated measurement principles.

We studied how nanoparticles form in the atmosphere at two different altitudes in Cyprus, focusing on how meteorology impacts this process. Using data from two sites, we found that air from lower regions carries particles up to higher areas, affecting air quality and potentially climate. Our findings help improve understanding of how particles form and grow in the air, which is important for predicting changes in climate and air pollution in the future.

The oxidative potential (OP) of air pollution particles might be a metric explaining particle toxicity. This study quantifies OP of particles of fresh and aged car and wood burning emissions and how OP changes over time, using novel high time resolution instruments. We show that emissions from wood burning are more toxic than car exhaust per particle mass, especially as they age in the atmosphere. We also calculate emission factors for OP, which could help to improve air pollution policies.

We developed a new method to measure how particles absorb light as they change in size, which is critical for understanding their climate impact. Our approach uses a sensitive instrument that measures light absorption directly from particles in real time. By pairing this with a device that sorts particles by size, we achieved accurate, size-resolved measurements. Our findings closely match theoretical models, offering a promising tool for future research into how particles influence climate.

We present a new photoacoustic instrument for simultaneous measurement of aerosol light absorption at multiple wavelengths. High performance is reached by using an optically-read cantilever microphone, which allows for highly sensitive absorption measurements at a compact size. Performance in field conditions is demonstrated with black carbon monitoring at an air quality measurement station, where our results agree well with reference instruments deployed at the site.

Insoluble aerosol particles such as minerals and black carbon can trigger freezing inside clouds, which leads to rain formation. However, both particle types are relatively poor nuclei for cloud droplets. In this work, theoretical calculations are presented about the ability of surface tension reducing compounds to promote cloud drop formation around insoluble aerosols. The calculations indicate that such surfactants can be efficient in "smuggling" insoluble particles into cloud droplets.

We investigated the space charge influence on the aerosol neutralization principle used in all aerosol measurement instruments. We found that the space charge cause ions to separate unevenly, leading to different rates of neutralization in different parts of the inlet, impacting the effectiveness of the neutralization process.

Our study explores particles in Arctic soils and streams that influence ice formation in clouds. By analysing these environments, we identified specific microorganisms producing these particles. This research, which measured these particles in Arctic streams for the first time, provides new insights into their ecological role and transfer from soil to water. Our findings help us understand their production, sources, and potential impact on climate.

The COVID-19 lockdown measures in 2020 reduced emissions of various substances improving air quality. However, PM2.5 stayed unchanged due to NH₃ and related chemical transformations. Higher humidity favoured more SO₄^2- production so as accumulated NH₃ did. Excess NH₃ neutralised HNO₃ towards NO₃^-. In high NH₃ conditions such as those in 2020, a small reduction of NO_x levels drives faster oxidation toward NO₃^- and slower deposition of total inorganic NO₃^- causing high secondary PM2.5.