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Displaying 1 - 25 of 51

DEVELOPMENT OF A MINIATURE, MULTICHANNEL, EXTENDED-RANGE FABRY-PEROT FIBER-OPTIC LASER INTERFEROMETER SYSTEM FOR LOW FREQUENCY SI-TRACEABLE DISPLACEMENT MEASUREMENT

October 12, 2014
Author(s)
Bartosz K. Nowakowski, Douglas T. Smith, Stuart T. Smith
Laser interferometry has become a staple of SI-traceable displacement measurement techniques. With decreasing cost per channel, miniaturization, and a multitude of commercially available off-the-shelf systems, these systems create ever more attractive

Accurate Spring Constant Calibration for very Stiff Atomic Force Microscopy Cantilevers

November 26, 2013
Author(s)
Scott Grutzik, Richard S. Gates, Yvonne B. Gerbig, Douglas T. Smith, Robert F. Cook, Alan Zehnder
There are many atomic force microscopy (AFM) applications that rely on quantifying the force between the AFM cantilever tip and the sample. The AFM does not explicitly measure force, however, so in such cases knowledge of the cantilever stiffness is

Development of a Precision Nanoindentation Platform

July 18, 2013
Author(s)
Douglas T. Smith, Bartosz K. Nowakowski, Robert F. Cook, Stuart T. Smith, Luis F. Correa
This paper presents the design, construction and performance of a surface- referenced nanoindentation instrument termed a precision nanoindentation platform (PNP). The PNP is a symmetrically designed instrument with a centrally located indenter tip

The increase in conductance of a gold single atom chain during elastic elongation

February 7, 2013
Author(s)
Francesca Tavazza, Shmuel Barzilai, Douglas T. Smith, Lyle E. Levine
The conductance of monoatomic gold wires has been studied using ab initio calculations and the transmission was found to vary with the elastic strain. Counter-intuitively, the conductance was found to increase for the initial stages of the elongation

Effect of the Spherical Indenter Tip Assumption on the Initial Plastic Yield Stress

October 17, 2012
Author(s)
Li Ma, Lyle E. Levine, Ronald G. Dixson, Douglas T. Smith, David Bahr
Nanoindentation is widely used to explore the mechanical properties of small volumes of materials. For crystalline materials, there is a growing experimental and theoretical interest in pop-in events, which are sudden displacement-burst excursions during

Nanomechanical standards based on the intrinsic mechanics of molecules and atoms

June 7, 2010
Author(s)
Jon R. Pratt, Gordon A. Shaw, Douglas T. Smith
For more than a decade, instruments based on local probes have allowed us to touch objects at the nanoscale, making it possible for scientists and engineers to probe the electrical, chemical, and physical behaviors of matter at the level of individual

An Ultra-Stable Platform for the Study of Single-Atom Chains

May 16, 2010
Author(s)
Douglas T. Smith, Jon R. Pratt, Francesca M. Tavazza, Lyle E. Levine, Anne M. Chaka
We describe a surface probe instrument capable of sustaining single-atomic-bond junctions in the electronic quantum-conduction regime for tens of minutes, and present results for Au junctions that can be locked stably in n = 1 and n = 2 quantum conduction

Methods for transferring the SI unit of force from millinewtons to piconewtons

June 1, 2009
Author(s)
Gordon A. Shaw, Koo-Hyun Chung, Douglas T. Smith, Jon R. Pratt
The establishment of standards for small force measurement requires a link to an absolute measurement of force traceable to the international system of units (SI). To this end, a host of different means are being employed by the NIST small force

Accurate Picometers for DC and Low-Frequency Displacement Measurement

April 6, 2009
Author(s)
Jon R. Pratt, Douglas T. Smith, Lowell Howard
We have developed a fiber-optic interferometer optimized for best performance in the frequency range from DC to 1 kHz, with displacement linearity of 1 % over a range of 25 nm, and noise-limited resolution of 2 pm [1]. The interferometer uses a tunable

Traceable Micro-Force Sensor for Instrumented Indentation Calibration

April 10, 2007
Author(s)
Douglas T. Smith, Gordon A. Shaw, R M. Seugling, D Xiang, Jon R. Pratt
Instrumented indentation testing (IIT), commonly referred to as nanoindentation when small forces are used, is a popular technique for determining the mechanical properties of small volumes of material. Sample preparation is relatively easy, usually

A Piezoresistive Cantilever Force Sensor for Direct AFM Force Calibration

April 8, 2007
Author(s)
Jon R. Pratt, John A. Kramar, Gordon A. Shaw, Douglas T. Smith, John M. Moreland
We describe the design, fabrication, and calibration testing of a new piezoresistive cantilever force sensor suitable for the force calibration of atomic force microscopes in a range between tens of nanonewtons to hundreds of micronewtons. The sensor is

Traceable Micro-Force Calibration for Instrumented Indentation Testing

February 13, 2007
Author(s)
Douglas T. Smith, Gordon A. Shaw, Richard Seugling, Jon R. Pratt, Dan Xiang
We describe the development, performance and application of an accurate SI-traceable force calibration and verification system for potential use in the field calibration of commercial instrumented indentation testing (IIT) instruments. The system consists

Contact Mechanics of Layered Elastic Materials: Experiment and Theory

January 26, 2007
Author(s)
P M. McGuiggan, Jay S. Wallace, Douglas T. Smith, I Sridhar, Z Zheng, K L. Johnson
This paper reports an experimental and theoretical investigation of the indentation of a layered elastic solid, with special reference to the surface force apparatus (SFA). The contacting surfaces of the SFA comprise a 3-layer material: a thin mica surface

A Novel Test Method for Measuring Mechanical Properties at the Small-Scale: The Theta Specimen

June 9, 2005
Author(s)
George D. Quinn, Lin-Sien H. Lum, Dan Xiang, Ajitkumar Jillavenkatesa, Li Ma, Douglas T. Smith
A test method has been developed for measuring mechanical properties of material structures at the small-scale. Round or hexagonal rings are compressed vertically on their ends thereby creating a uniform tension stress in a horizontal crossbar that serves