1. Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603, Singapore
2. Department of Physics, National University of Singapore, Singapore 117542, Singapore
3. NUSSNI-NanoCore, National University of Singapore, Singapore 117576, Singapore
4. National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), 28 Medical Drive, Singapore 117456, Singapore