1. Department of Physics, The University of Texas at Dallas, Richardson, Texas 75080, United States
2. Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
3. The Center for Photochemical Sciences and Department of Physics, Bowling Green State University, Bowling Green, Ohio 43403, United States
4. Nanohmics Inc., 6201 E. Oltorf, Suite 400, Austin, Texas 78741, United States
5. Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, United States