1. National Institute of Standards and Technology, Materials Science & Engineering Laboratory, Gaithersburg, MD 20899, USA
2. Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974, USA
3. University of North Florida, Department of Chemistry & Physics, Jacksonville, FL 32224, USA
4. University of Florida, Department of Materials Science & Engineering, Gainesville, FL 32611‐6400, USA