- Small-force metrology: The development and application of methods and instrumentation for the calibration of force in the range from millinewtons to nanonewtons.
- Atomic scale displacement measurement: The development and use of specialized, high-accuracy interferometry techniques for the measurement of strain in atomic structures, with accuracy better than 10 picometers.
- Nanomechanics: The design, construction and use of instruments for the accurate measurement of mechanical properties and deformation of materials at the nanometer and atomic scale.
Figure 1: A force cell (brass cover, foreground) for traceable force calibration of micro- and nano-mechanical testing instruments. The cell covers the force range from 5 µm to 5 mN with 0.25 % accuracy or better. In the background is a turret loading system for automated calibration using NIST-traceable mass artifacts (small stainless steel wires) covering the range 0.5 mg to 500 mg.
Figure 2(right): A schematic of a fiber-optic interferometer system designed and built at NIST that is capable of measuring changes in the length of a Fabry-Perot cavity with 2 pm resolution for quasistatic changes, and with 40 fm resolution when using AC dithering of the cavity length. The interferometer output can, for example, be used to servo-control the position of an atomic probe above or in contact with a surface with long-term picometer-level stability.
Figure 3: (a) Quantized electrical conduction through a single-atom contact between a gold probe and a gold surface as the probe position is moved a total of approximately 3 nm (b). The probe position is stabilized using the interferometer system shown in Figure 2.
Postdoctoral Research Opportunities:
Mechanical Behavior at Ultra-Small Length Scales
Nanoindentation for Mechanical Property Determination
Post-doctoral research opportunities exist in a wide range of experimental activities related to accurately measuring the deformation of materials at the nanometer and atomic scale. Both commercial and custom instruments are available, and new and improved instruments and methodologies are constantly being developed and applied to materials testing problems of current interest to high-tech U.S. industries.
Awards and Honors
- Silver Medal Award, U.S. Dept. of Commerce, 2004
- Silver Medal Award, U.S. Dept. of Commerce, 1990
Nanomechanical Properties Group
2006-present: Physicist, Ceramics Division, NIST
2005-2006: Program Analyst, NIST Office of the Director
2003-2005: Group Leader, Nanomechanical Properties, Ceramics Division, NIST
2001-2003: Group Leader, Thin Film Characterization and Properties Group, Ceramics Division, NIST
1991-2001: Physicist, Ceramics Division, NIST
1988-1991: NRC Postdoctoral Fellow, Ceramics Division, NIST
Ph.D., Physics, University of Massachusetts, 1988
B.S., Physics, Pennsylvania State University, 1983