Research Project:

Electron microscopy (EM) has been at the forefront of atomic imaging in recent decades, predominately dominated by transmission EM (TEM) and scanning transmission EM (STEM). The use of highly energetic electrons to image materials can have the adverse effect of damaging the material, creating so called defects. One such defect is the Stone-Wales (SW) defect that is of interest in graphene due to the change of properties of the local environment it causes through a 90o  carbon-carbon bond rotation. When using low energy imaging conditions (<80 keV), it should be impossible to create such defects in graphene. However, recent imaging has proven otherwise.

One theorised cause for this is the presence of an atom or molecule offering an alternative lower energy pathway. These species are present due to non-ideal vacuum in the microscope allowing gases into the column, with water vapour being the most important. Theories suggest that hydrogen can act as an energy mediator, accelerating the damage rate to graphene. 

The project aims to identify the impact hydrogen gas has on the rate of SW formation in graphene at different electron accelerating voltages using both TEM (FEI Titan) and STEM (Nion UltraSTEM 100). The experiments will be carried out at two accelerating voltages (60 keV and 80 keV) and two vacuum pressures (1x10-10mbar and 1x10-7mbar).

First stay:         March 8 - April 5, 2019
Second stay:    June 7 - July 7, 2019