1. Center of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Science; City University of Hong Kong; Hong Kong SAR
2. Department of Biology and Chemistry; City University of Hong Kong; Hong Kong SAR
3. Department of Physics and Materials Science; City University of Hong Kong; Hong Kong SAR
4. School of Chemistry and Forensic Sciences; Faculty of Life Sciences; University of Bradford; United Kingdom BD7 1DP