1.Develop an experimental flow reactor for harvesting alkyl radicals formed in hydrogen abstraction reactions, associated analytical instrumentation and a detailed chemical model that can describe the effects of impurities upon reaction mixtures: A detailed chemical model was built in the initial stages of this project in order to identify the experimental limitations of the approach, e.g. the maximum concentration of impurities such as O2 that can be tolerated, and the concentrations and reaction times that would be optimum. Following this, an analytical sampling approach was developed. This consisted of refurbishing/ upgrading a system that can be used for concentrating a compound of interest from a dilute sample, extracting those compounds that will interfere with the analytical approach (mainly H2O), and delivering a sharp pulse of analyte into a GC with an electron-capture detector. Other tasks were producing the reactor and making the apparatus extremely vacuum tight, such that residual O2 could be effectively removed and that O2 leaking in from the atmosphere would have a negligible effect upon reactor chemistry.
2.Develop experiments for determining the fate of stabilised Criegee intermediates (CIs) with respect to several atmospheric gases, and understanding the global significance of these reactions: An existing experimental method was upgraded to afford measurements as a function of temperature, several systems were studied including different CIs with trifluoroacetic acid, methanol, ethanol, hydrogen sulphide and methyl mercaptan. This work provided the opportunity to mentor the 1st masters student associated with this project. These activities have produced two publications, with several others planned.
3.Develop methods for determining the fate of excited CIs and their effects in the atmosphere. Commissioning a chamber apparatus and developing a technique for quantifying the production of extremely long-lived compounds that are generated when commercial compounds (HFOs) react with ozone in the atmosphere. A series of kinetic experiments were conducted on several HFOs. Given the extremely slow reactions, it was necessary to employ new experimental techniques to reduce the effects of unwanted byproducts. These include stabilised CIs, and using kinetic data from phase 2 enabled the design of experiments where CIs were converted into a less reactive form. This provided the opportunity to train an EPSRC intern and the 2nd masters student of this project. One paper describing this work is being written up.
4.Communicating scientific ideas and results. Managing 3 undergraduate research projects, providing talks in student-/early career-led fora; providing seminars at UK universities (Cambridge, Leicester, Bristol) and NCAR, CO, USA. Two posters were presented, one at EGU, Vienna, Austria in 2017, and one at the Faraday Discussions, York, UK in 2017. I was able to reach out to development scientists at Honeywell, the corporation responsible for the development of HFOs and provided them with a lab tour and a summary of our findings. Furthermore, I was invited to become a participant of an international panel of experts on structure-activity relationships and reaction mechanisms, this is organised under the auspices of the CRC and serves the atmospheric science community by providing articles, datasets and other resources, enabling the prediction of many kinetic parameters that have yet to be measured.
