1. Department
of Mechanical Engineering, National University of Singapore, Block EA
#07-08, 9 Engineering Drive 1, Singapore 117576, Singapore
2. Department
of Chemistry, University of Oslo, Blindern, P.O.
Box 1033, 0315 Oslo, Norway
3. Department
of Physics, University of Oslo, Blindern, P.O.
Box 1048, 0316 Oslo, Norway