1. Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong S.A.R., China
2. Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, USA
3. Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong S.A.R., China
4. Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong S.A.R., China