1. Department of Physics, Queens College, City University of New York (CUNY) and Center for Photonic and Multiscale Nanomaterials, Flushing, NY 11367, USA.
2. Department of Physics, Graduate Center, CUNY, New York, NY 10016, USA.
3. Department of Electrical and Computer Engineering, University of Alberta, Edmonton T6G 2V4, Canada.
4. Birck Nanotechnology Center, School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907, USA.
5. Department of Chemical Engineering, City College, CUNY, New York, NY 10031, USA.