Photolysis reaction mechanisms with emerging and new technologies

Background

Photochemistry controls a vast array of the natural and man-made processes known to science: photosynthesis, atmospheric and combustion chemistry, plasma technology, solar energy. Despite the importance of the subject, experimental limitations have inhibited the study of even the simplest processes by which small gas-phase molecules interact with chemically active ultra violet (UV) light. In this project you will exploit new and emerging technologies such as UV LEDs, chemosensors (developed in York) for sensitive and selective free-radical detection, online chemical ionisation mass spectrometry, and modern powerful computational methods to study photolysis reactions.

Among the largest classes of chemicals are “carbonyls” – organic molecules containing carbonyl functionality. Carbonyls are used in in a vast array of industrial applications, including directly as solvents, pesticides and biofuels, and as reagents for production of pharmaceuticals, polymers and aromachemicals. Carbonyls are ubiquitous in both indoor and outdoor air. Direct emissions are supplemented by in-situ production as virtually all organic compounds break-down to CO2 and H2O via a host of carbonyl intermediates. The photochemistry of carbonyls is both interesting and important, as unusually among atmospheric organics, they are broken down by abundant UV-A radiation. This project is particularly timely, as the photochemical environment is rapidly changing indoors. LED lighting is replacing fluorescent and incandescent technology, whilst UV and plasma based air filtration systems are increasingly used in an effort to enhance indoor air quality and to suppress virus spread.

Objectives:

To determine absorption cross-sections and photolysis quantum yields for a variety of gas-phase carbonyls; to assess photolysis rates and hence air quality impacts; to identify chemical structures and additional functionalities in carbonyls impacting on photolysis rates.

Experimental Approach:

A newly commissioned fast-flow reactor equipped with chemosensors and PTR-MS for quantum yield determinations; pulsed laser photolysis – laser induced fluorescence; UV-vis. spectroscopy for absorption cross-sections; GAUSSIAN for thermodynamic calculations and chemical structure determinations; the master chemical mechanism mcm.york.ac.uk for environmental impact assessment.

Training

All Chemistry research students have access to our innovative Doctoral Training in Chemistry (iDTC): cohort-based training to support the development of scientific, transferable and employability skills: https://www.york.ac.uk/chemistry/postgraduate/cdts/

Bespoke training and support will be provided by supervisors and the atmospheric science, laser photochemistry teams in York:

www.york.ac.uk/chemistry/research/wacl/

www.york.ac.uk/chemistry/research/photochemistry-spectroscopy/

As full training is provided, no specific experience or expertise is required e.g. with lasers or GAUSSIAN.

Equality, Diversity and Inclusion

The Department of Chemistry holds an Athena SWAN Gold Award and is committed to supporting equality and diversity for all staff and students. The Department strives to provide a working environment which allows all staff and students to contribute fully, to flourish, and to excel: https://www.york.ac.uk/chemistry/ed/.

Your background

You should expect hold or expect to achieve the equivalent of at least a UK upper second class degree in Chemistry or a related subject. Please check the entry requirements for your country: https://www.york.ac.uk/study/international/your-country/