1. Department
of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551
2. Centre for BioImaging
Sciences, Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543
3. Centre
for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546
4. NanoCore, National University of Singapore, 4 Engineering Drive 3, Singapore 117576