[1] Univ Hong Kong, Dept Phys, Hong Kong, Hong Kong, Peoples R China
[2] Univ Hong Kong, Dept Chem, Hong Kong, Hong Kong, Peoples R China
[3] Hong Kong Polytech Univ, Dept Elect & Informat Engn, Kowloon, Hong Kong, Peoples R China
[4] Hong Kong Baptist Univ, Dept Phys, Kowloon Tong, Hong Kong, Peoples R China