1. Nanoscale Device Characterization Division, PML, NIST, Gaithersburg, Maryland 20899, United States
2. Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37212, United States
3. Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States
4. Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37212, United States
5. Vanderbilt Institute of Nanoscale Sciences and Engineering, Nashville, Tennessee 37212, United States