1. Department of Physics; The University of Hong Kong; Pokfulam Road Hong Kong
2. Department of Electronic and Information Engineering; The Hong Kong Polytechnic University; Hung Hom Kowloon Hong Kong
3. Department of Chemistry; The University of Hong Kong; Pokfulam Road Hong Kong
4. Department of Physics; South University of Science & Technology of China; Tangchang Road Nanshan District Shenzhen Guangdong 518055 China
5. Department of Civil Engineering; The University of Hong Kong; Pokfulam Road Hong Kong