1. Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2V4
2. National Research Council (NRC), National Institute for Nanotechnology (NINT), Edmonton, Alberta, Canada T6G 2M9
3. Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
4. Quantachrome, 1900 Corporate Drive, Boynton Beach, Florida 33426