This PhD opportunity will be in the Molecular Scattering research group at Heriot-Watt University, Edinburgh.
Please contact Prof Ken McKendrick ([Email Address Removed]) for further details.
You will develop and exploit novel, laser-based techniques to probe the scattering of key reactive molecules, such as the OH radical, at liquid surfaces. These reactions are the first elementary step in the ‘ageing’ of atmospheric aerosol particles, in which primary pollutants are oxidised to more hydrophilic species. This affects the ability of the aerosol particles to act as cloud condensation nuclei and changes their optical properties, both of which have important climatic consequences. The method we have developed to probe these reactions uses laser pulses to generate sequences of real-space images by exciting laser-induced fluorescence from the OH molecules as they travel towards and are scattered from the liquid surfaces. From these ‘movies’ of the scattering process, we can deduce how much of the OH survives a collision with the surface, and its resulting speed and angular distributions. This provides unprecedented mechanistic insight on reactions at different surfaces. So far, we have examined some relatively simple model surfaces, but are now moving on to a wider range of more complex chemical functionality more representative of real atmospheric aerosols. We also aim to use custom-designed self-assembled monolayer surfaces to investigate reactions with important functional groups which may not be easy to study in liquids. The interpretation of the experiments is assisted by complementary molecular dynamics simulations of liquid surface structures. There is scope to extend the experiments through additional novel laser-absorption methods that probe the products of these reactions directly. This work is part of a large collaboration funded through a major joint EPSRC Programme Grant (https://molecularscattering.com/) with University of Oxford, involving regular interactions and the opportunity for exchange visits.