a
Department of Chemistry, Carnegie Mellon University, Pittsburgh, USA
E-mail: rongchao@andrew.cmu.edu
;
Fax: +1 4122681061
;
Tel: +1 4122689448
b
Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, USA
c
Department of Chemistry, Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Xiangtan University, China