Contacts: [email protected]; [email protected]
Volatility is an important property of aerosols that affects how long they stay in the atmosphere, how they impact air pollution and climate and could inform us on the aerosol sources. Volatility influences whether molecules can form new aerosol particles or condense on existing ones, which in turn affects the chemical composition and amount of aerosol in the air. While it’s relatively easy to measure volatility for simple molecules, it becomes much harder when dealing with the complex mixtures found in the ambient air, with thousands of unknown constituent molecules. Unfortunately, we still lack detailed measurements of how aerosol volatility and composition change with height in the atmosphere because of limitations in current instruments.
To address this, our lab developed a miniaturized thermodenuder instrument with the aim of flying it using our tethered balloon. The thermodenuder consists of a heating section where components of the aerosol are evaporated based on their volatility, followed by a denuder section where the evaporated gas-phase is removed. By measuring the particle size distribution at different temperatures, we can look into the evaporation behaviours of aerosols.
The goal of this master’s thesis is to develop a numerical thermodynamic model of the evaporation inside the thermodenuder instrument, linking the observations of aerosol evaporation to their volatility. For this, there are a number of existing model frameworks which can be adapted to our instrument. The model can then be validated with simple known molecules using lab experiments. Finally, the model should be applied to ambient atmospheric aerosols measured from our lab in Sion.
This project is based both on lab experiments for validation, and coding for the model development. It should therefore be a good chance to get experience with analytical instrumentation and develop/prove your coding ability. Previous programming experience would be an advantage.