Events in Physics
Tuesday, March 11, 2014
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CMP seminar - Studying Defects in Graphene at Atomic Resolution byJamie Warner, University of OxfordMAS 2.06Defects in graphene influence its electronic, magnetic, chemical and mechanical properties. It is therefore important to have a detailed understanding of their exact atomic structure in order to accurately predict their behaviour. In this talk I will present a summary of our latest work on resolving the atomic structure of vacancy defects in graphene, single atom dopants covalently bonded in the lattice, and their transition dynamics.1-5 By using aberration-corrected transmission electron microscopy, combined with monochromation of the electron source to reduce chromatic aberration effects, we can achieve sub-Angstrom spatial resolution at a low accelerating voltage of 80 kV. We have developed a method to introduce defects into the lattice of graphene with 10 nm spatial accuracy within the electron microscope using a controlled focussed beam. This enables the study of defect structures with unprecedented clarity and accuracy. We combine our TEM imaging with DFT calculated atomic models to gain deeper insights into the C-C bond lengths and their relationship to changes in electronic charge distribution. 1. J. H. Warner et al. Science, 337, 209 (2012) 2. A. W. Robertson et al. Nature Communications, 3, 1144 (2012) 3. K. He et al. Nature Comm. 5, 3040 (2014) 4. A. W. Robertson et al. Nano Letters, Articles ASAP DOI: 10.1021/nl404266k (2014) 5. J. H. Warner et al. ACS Nano, 7, 9860. (2013) |