1. Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
2. Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA, United Kingdom
3. Gonville and Caius College, Trinity Street, Cambridge CB2 1TA, United Kingdom
4. Diamond Light Source, Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom