Name of scholarship/program
Kinetics and photochemistry of gas phase and heterogeneous reactions on aerosols in atmospheric and astrochemical environments
The purpose of this project is to improve our understanding of fundamental aspects of the atmospheric photo-oxidation chemistry of the Earth and other planets and moons, as well as in star-forming regions and the interstellar medium. Air quality and climate change models are used to predict the future impact of changing emissions into Earths atmosphere, and drive legislative control. It is important that the chemistry within these models is accurate, and each reaction in the model requires a rate coefficient and branching ratio for the products to be specified under relevant conditions. In space, a variety of free-radical species and organic molecules have been detected using telescopes, yet their low-temperature chemistry, how they are formed and removed, is very poorly understood.
Eligibility and other criteria
An aerosol flow-tube coupled to a ultra-sensitive detector based on laser-induced fluorescence spectroscopy at low pressure (FAGE) will be used to study reactions of free-radicals on the surface of sub-micron aerosols of differing chemical composition (e.g. dry and aqueous salts, organics, mineral dust) as a function of humidity and temperature. We are interested in both the impacts on the gas phase radicals and oxidative changes in the ageing aerosol. A pulsed Laval nozzle apparatus will be used to study the kinetics of reactions at very temperatures representative of the atmospheres of other planets and moons, for example Titan, as well as in star-forming regions, stellar outflows and the interstellar medium. We have recently observed spectacular negative temperature dependences, for example in the rate coefficients of reactions of OH with acetone and methanol, which are very fast at 60 - 120 K. The experimental data are interpreted using theoretical methods, making use of ab initio potential energy surfaces and master equation calculations (using the MESMER program, developed in Leeds) to calculate rate constants as a function of temperature and pressure. These experiments, which currently use laser flash-photolysis combined with laser-induced fluorescence (LIF) spectroscopy, will be extended to study further reactions of OH and other radicals, and will monitor both reactants and products, using LIF and perhaps soft-ionisation mass spectrometry.
This research project is one of a number of projects at this institution. It is in competition for funding with one or more of these projects. Usually the project which receives the best applicant will be awarded the funding. Applications for this project are welcome from suitably qualified candidates worldwide. Funding may only be available to a limited set of nationalities and you should read the full department and project details for further information.
Applications accepted all year round
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