Cracking the problem of heterogeneous nucleation: identifying the sites responsible for ice nucleation

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A fundamental understanding of the formation of ice is critical for a range of fields. However, we have very limited knowledge of why certain materials trigger the formation of ice, while others do not. It is thought that specific sites on surfaces which are perhaps just a few 10s of nanometers squared are responsible for nucleation, but these sites can occupy only 10-10 % of the surface. Hence, they are incredibly difficult to identify and characterise and our understanding of them remains extremely poor.In this PhD project the student will focus on improving our basic knowledge of ice nucleation through novel laboratory experimentation utilising the unique equipment and resources which have been developed in the Leeds Ice Nucleation Group. The student will also be uniquely positioned to exploit their discoveries in the fields of: nucleation of ice in clouds and the control of the formation of ice in biological samples during cryopreservation. Ice nucleation in clouds helps define life on Earth since clouds play a central role in our planet's climate and its hydrological cycle, while the control of ice nucleation is a key limitation in a range of areas, such as the supply of cells for the high throughput toxicology screening of pharmaceutical products. Objectives:1. Identify nucleation sites using our existing cryo-microscope equipped with a high speed camera to study ice nucleation on thin sections of mineral samples.2. Test the response of these sites to the presence of salts and acids. We know that salts can either enhance or deactivate ice nucleation, but do not understand why. Acids can deactivate nucleation sites, but linking this deactivation to changes in surface properties has never been done before. 3. Use advanced imaging techniques to probe the properties of the sites which cause ice nucleation. 4.Potentially use the new knowledge of what makes an effective ice nucleation site in order to artificially create ice nucleation sites which might be used for the control of ice nucleation in applications such as cryopreservation. This would be an excellent opportunity to interact with our partner cryopreservation company.5. Potentially take part in a field campaign. While this project is laboratory focused, there will be opportunities to take part in field campaigns around the world where we study ice nucleation. In past campaigns we have travelled to the high Arctic, Barbados and Iceland, amongst other places. We also work on the UK research aircraft (FAAM) and research ships.