1. Department of Materials Science and Engineering; National University of Singapore; 117575 Singapore
2. NUSNNI-Nanocore; National University of Singapore; 117411 Singapore
3. Engineering Science Programme; National University of Singapore; 117575 Singapore
4. Singapore Synchrotron Light Source (SSLS); National University of Singapore; 5 Research Link 117603 Singapore
5. Department of Physics; National University of Singapore; 117542 Singapore
6. Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience; University of Nebraska; Lincoln NE 68588-0299 USA
7. Department of Electrical and Computer Science Engineering; National University of Singapore; 117576 Singapore
8. Department of Integrative Science and Engineering; National University of Singapore; 117576 Singapore