Electron ptychography is a newly available mode of imaging in the transmission electron microscope that is somewhat related to holography and can provide very precise measurements of the electrostatic potential in a crystal. Recent work in Oxford has shown that it can provide a measurement of the charge transfer between boron and nitrogen in a hexagonal boron nitride monolayer. This work demonstrates the potential of ptychography for measuring the effect of bonding on wavefunctions and charge densities in crystals – a field now known as quantum crystallography. The aim of this work is to develop this method to measure the effects of bonding in a range of different materials, such as compound nanomaterials and transition metal oxides. It will involve developing the experimental and data processing approaches, and developing methods based on density functional theory modelling to interpret the experimental data. Projects are available that have either a more experimental emphasis applying the method to a range of materials, or a greater emphasis on developing the theoretical modelling methods to improve how the experimental results can be interpreted.
The description above outlines a possible new research project being offered to prospective new postgraduate students.