This PhD project will support the objectives of a Leverhulme grant awarded to Dr. Derek Wann and colleagues to investigate solvation processes relevant to homogenous chemical catalysis. In many catalytic reactions the solvent is the single greatest component of the solution, but remarkably, the nature of direct molecular interactions between catalysts and solvents has hitherto been largely ignored. The bigger project will see us combine a suite of state-of-the-art experimental methods including time-resolved electron diffraction and ultrafast infrared spectroscopy to follow catalyst-solvent interactions continuously over 18 orders of magnitude in time, following reactions from initiation to completion. By focussing on the behaviour of modern Earth-abundant metal catalysts, based on manganese and cobalt, the results will have direct application to the replacement of expensive and rare metals such as rhodium and platinum.
The specific role of electron diffraction – and the focus of this PhD project – will be to study the gas-phase structures in the absence of solvent for transition metal complexes both as time-averaged structures, and also using time-resolved electron diffraction to understand structural changes upon laser-induced excitation leading to bond-breaking processes.
The objectives of this project will include:
· Working with synthetic groups to ensure a supply of catalytically relevant transition metal complexes [e.g. MnMe(CO)5] to study.
· Adapting the time-averaged and time-resolved electron diffraction apparatus in York to enable the gas-handling systems to work for transition metal complexes (e.g. designing new heating methods).
· Working with the existing Ti:sapphire laser set-up to improve the efficiency of the time-resolved electron diffraction apparatus to work alongside relevant spectroscopic apparatus.
· Collecting and analysing data, including adapting existing codes to enable refinements to be carried out, and performing quantum chemical calculations in support of the experimental work.
This project will make use the time-averaged electron diffraction apparatus in York, which is composed of a continuous electron beam (42 keV) produced from a tungsten filament. Following diffraction of this electron beam through a gaseous sample, diffraction patterns are collected on image plates, before being scanned and analysed computationally to interpret the molecular structure of any sample. These initial experiments will give insight into the conditions required for collecting data in the gas phase, as well as yielding the ground-state structures.
Samples will then be studied using the time-resolved apparatus in York, where a pulsed beam of electrons (100 keV) is generated from the interaction of a 266 nm laser beam with a gold photocathode. A different branch of the same laser will be used to photoexcite transition-metal samples in the gas-phase leading to electronic excitation and ultimately bond-breaking processes. Diffraction patterns in this experiment are recorded using a phosphor-screen/CCD camera set-up, and time resolution down to 1 ps can be achieved using this apparatus.
Quantum chemical calculations will yield important information that will guide the experimental design and data analysis.
Opportunities to use central facilities both in the UK, and in Europe and the US will be taken should we have samples for which additional time resolution, down to 200 fs, will be required. Such experiments require MeV electron beams where relativistic effects are negligible.
While electron diffraction has been known for the best part of 100 years, time-resolved experiments, especially for chemically-interesting samples are very much in their infancy. The use of electron diffraction to aid these studies of solvation is entirely novel.
The student will be trained in a variety of experimental methods, including electron diffraction, laser use, and general pump-probe methodologies. Training in the use of software packages will also be provided. 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/
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/.
For more information about the project, click on the supervisor's name above to email the supervisor. For more information about the application process or funding, please click on email institution
This PhD will formally start on 1 October 2022. Induction activities may start a few days earlier.
To apply for this project, submit an online PhD in Chemistry application:
You should hold or expect to achieve the equivalent of at least a UK upper second class degree in Chemistry or a related subject.