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Search Publications by: Jon R. Pratt (Fed)

Displaying 76 - 100 of 230

Towards a fixed value of the Planck constant: reproducibility and an updated NIST-3 watt balance

July 1, 2012

Author(s)

Darine El Haddad, Stephan Schlamminger, David B. Newell, Ruimin Liu, Edwin R. Williams, Jon R. Pratt

The scientific community is presently engaged in a historic attempt to fix the value of the Planck constant h so that it might ultimately serve as a base constant in a revised system of units. To assist this effort, NIST is examining its existing watt

Report on the first international comparison of small force facilities: A pilot study at the micronewton level

November 28, 2011

Author(s)

Jon R. Pratt, Min-Seok Kim, Uwe Brand, Christopher Jones

Measurements of forces less than a micronewton are critical when examining the mechanical behaviors of materials and devices at characteristic length scales below a micrometer. As a result, standards for nanomechanical tests and test equipment are being

Electron Transport in Gold Nanowires: Stable 1-, 2- and 3-Dimensional Atomic Structures and Non-Integer Conduction States

September 14, 2011

Author(s)

Francesca M. Tavazza, Douglas T. Smith, Lyle E. Levine, Jon R. Pratt, Anne M. Chaka

Experimental conductivity measurements made during highly stable tensile deformation of Au nanowires show a rich variety of behaviors, including non-integer quantum conductance plateaus, transitions and slopes. Using tight binding conductance calculations

Calibration of dynamic sensors for noncontact-atomic force microscopy

August 12, 2011

Author(s)

Gordon A. Shaw, Jon R. Pratt, Zeina J. Kubarych

Access to quantitative information on surface forces in noncontact-atomic force microscopy (NC-AFM) requires the accurate calibration of several key sensor parameters. This work outlines a dynamic method for calibrating the spring constant of tuning fork

Atomic Force Microscope Cantilever Flexural Stiffness Calibration: Toward a Standard Traceable Method

July 1, 2011

Author(s)

Richard S. Gates, Mark Reitsma, John A. Kramar, Jon R. Pratt

The evolution of the atomic force microscope into a useful tool for measuring mechanical properties of surfaces at the nanoscale has spurred the need for more precise and accurate methods for calibrating the spring constants of test cantilevers. Groups

An interferometric platform for studying AFM probe deflection

January 3, 2011

Author(s)

Jon R. Pratt, Lee Kumanchik, Tony L. Schmitz

This paper describes an interferometric platform for measuring the full-field deflection of atomic force microscope (AFM) probes and generic cantilevers during quasi-static loading. The platform consists of a scanning white light interferometer (SWLI)

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

Small mass measurements for tuning fork-based force microscope cantilever spring constant calibration

June 7, 2010

Author(s)

Gordon A. Shaw, Jon R. Pratt, Zeina J. Kubarych

Cutting edge mass sensors are capable of discriminating mass changes as small as several dozens of atoms, however the smallest mass commercially available from NIST with a calibration traceable to the International System of Units (SI) is 0.5 mg. To bridge

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

Quantitative assessment of sample stiffness and sliding friction from force curves in atomic force microscopy

February 18, 2010

Author(s)

Jon R. Pratt, Gordon A. Shaw, Lee Kumanchik, Nancy Burnham

It has long been recognized that the angular deflection of a typical atomic force microscope (AFM) cantilever under normal loading conditions can be profoundly influenced by the friction between the tip and the surface. It is shown here, that a remarkably

Lateral Force Calibration: Accurate Procedures for Colloidal Probe Friction Measurements in Atomic Force Microscopy

January 19, 2010

Author(s)

Koo-Hyun Chung, Jon R. Pratt, Mark Reitsma

The colloidal probe technique for atomic force microscopy (AFM) has allowed the investigation of an extensive range of surface force phenomena, including the measurement of frictional (lateral) forces between numerous materials. The quantitative accuracy

SI Traceability: Current status and future trends for forces below 10 micronewtons

September 24, 2009

Author(s)

Jon R. Pratt

Measurements related to nano- and micro- scale science, technology, and manufacturing are pushing the limits of detectable mechanical, electrical, and chemical quantities to ever smaller values, raising important questions regarding how best to extend the

Accurate Picoscale Forces for Insitu Calibration of AFM

September 3, 2009

Author(s)

Koo-Hyun Chung, Gordon A. Shaw, Jon R. Pratt

The force sensitivity of an atomic force microscope is calibrated directly using an in situ realization of primary electrostatic forces ranging from 320 pN to 3.3 nN with accuracy of a few percent. The absolute accuracy of a common atomic force microscope