Improving the understanding of the gas/particle partitioning behaviour of organic aerosols in different environmental conditions 

Theme: Basic processes

Start date: Cohort 1: 2019

Supervisors: Prof Jonathan Reid (Bristol) and Dr David Topping (Manchester)

Understanding the partitioning of molecular constituents between the gas and particle phases is central to the whole endeavour of aerosol science. This project applies ultra-sensitive techniques to investigate the volatilisation of low and semi-volatile components from aerosol particles, their response to humidity and temperature, and refining predictive tools crucial for understanding air quality.


Organic aerosols are an important class of aerosol to study due to their effect on climate, weather systems, human health and global ecosystems. Despite their importance, they remain poorly understood due to their molecular complexity, reactivity and large diversity in properties. The lack of accurate vapour pressure (VP)data of organic species –including natural atmospheric, intentionally released and anthropogenic more broadly –accompanied by the large uncertainty in the estimation of their VPs has been presented as the focus for improvement in this proposal. A research plan involving the use of electro-dynamic balances and aerosol optical tweezers to experimentally determine the vapour pressures of important organic species has been proposed, along with the use of this data in improving current vapour pressure estimation methods for organic compounds. The subsequent coupling of an improved VP estimation model into an aerosol box model, “PyBox”, with the consideration of kinetic effects such as viscosity and reactions upon drying has also been proposed. The main challenges that will likely accompany the work have been identified and discussed. Lastly, the project has been considered from a responsible innovation point of view to assess the likelihood of any unintended outcomes from the research.