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Quantitative Assessment Of Sample Stiffness And Sliding Friction From Force Curves In Atomic Force Microscopy, Nancy Burnham, Jon Pratt, Gordon Shaw, Lee Kumanchik
Quantitative Assessment Of Sample Stiffness And Sliding Friction From Force Curves In Atomic Force Microscopy, Nancy Burnham, Jon Pratt, Gordon Shaw, Lee Kumanchik
Nancy A. Burnham
It has long been recognized that the angular deflection of an 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 quantifiable hysteresis occurs in the slope of loading curves whenever the normal flexural stiffness of the AFM cantilever is greater than that of the sample. This situation arises naturally in cantilever-on-cantilever calibration, but also when trying to measure the stiffness of nanomechanical devices or test structures, or when probing any type of surface or structure that is much more compliant along …
Precision And Accuracy Of Thermal Calibration Of Atomic Force Microscopy Cantilevers, Nancy Burnham, G Matei, E Thoreson, J Pratt, D Newell
Precision And Accuracy Of Thermal Calibration Of Atomic Force Microscopy Cantilevers, Nancy Burnham, G Matei, E Thoreson, J Pratt, D Newell
Nancy A. Burnham
To have confidence in force measurements made with atomic force microscopes(AFMs), the spring constant of the AFM cantilevers should be known with good precision and accuracy, a topic not yet thoroughly treated in the literature. In this study, we compared the stiffnesses of uncoated tipless uniform rectangular silicon cantilevers among thermal, loading, and geometric calibration methods; loading was done against an artifact from the National Institute of Standards and Technology (NIST). The artifact was calibrated at NIST using forces that were traceable to the International System of units. The precision and accuracy of the thermal method were found to be …
Apparent And True Feature Heights In Force Microscopy, Nancy Burnham
Apparent And True Feature Heights In Force Microscopy, Nancy Burnham
Nancy A. Burnham
In a force microscope, the stiffness of the cantilever beam convolutes with the tip‐sample interaction stiffness to influence the data in a systematic way. The analysis presented here relates the measured feature height to the true feature height in the variable force, constant force, and constant force gradient modes of operation. In this way, one can understand previously published data: the enhanced measured atomic corrugation observed in high resolution force microscopy images, its increase with load, and the improved resolution of lateral force images. The correct interaction stiffness can be obtained for use in surface force and mechanical properties studies. …
Atomistic Mechanisms And Dynamics Of Adhesion, Nanoindentation, And Fracture, Nancy Burnham, Uzi Landman, Wd Luedtke, Richard Colton
Atomistic Mechanisms And Dynamics Of Adhesion, Nanoindentation, And Fracture, Nancy Burnham, Uzi Landman, Wd Luedtke, Richard Colton
Nancy A. Burnham
Molecular dynamics simulations and atomic force microscopy are used to investigate the atomistic mechanisms of adhesion, contact formation, nanoindentation, separation, and fracture that occur when a nickel tip interacts with a gold surface. The theoretically predicted and experimentally measured hysteresis in the force versus tip-to-sample distance relationship, found upon approach and subsequent separation of the tip from the sample, is related to inelastic deformation of the sample surface characterized by adhesion of gold atoms to the nickel tip and formation of a connective neck of atoms. At small tipsample distances, mechanical instability causes the tip and surface to jump-to-contact, which …