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Full-Text Articles in Physics
On The Electrochemical Etching Of Tips For Scanning Tunneling Microscopy, Nancy Burnham, J. Ibe, P. Bey Jr., S. Brandow, R. Brizzolara, D. Dilella, K. Lee, C. K. Marrian, R. Colton
On The Electrochemical Etching Of Tips For Scanning Tunneling Microscopy, Nancy Burnham, J. Ibe, P. Bey Jr., S. Brandow, R. Brizzolara, D. Dilella, K. Lee, C. K. Marrian, R. Colton
Nancy A. Burnham
The sharpness of tips used in scanning tunneling microscopy(STM) is one factor which affects the resolution of the STM image. In this paper, we report on a direct‐current (dc) drop‐off electrochemicaletching procedure used to sharpen tips for STM. The shape of the tip is dependent on the meniscus which surrounds the wire at the air–electrolyte interface. The sharpness of the tip is related to the tensile strength of the wire and how quickly the electrochemical reaction can be stopped once the wire breaks. We have found that the cutoff time of the etch circuit has a significant effect on the …
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 …
Probing The Surface Forces Of Monolayer Films With An Atomic-Force Microscope, Nancy Burnham, Dawn Dominguez, Robert Mowery, Richard Colton
Probing The Surface Forces Of Monolayer Films With An Atomic-Force Microscope, Nancy Burnham, Dawn Dominguez, Robert Mowery, Richard Colton
Nancy A. Burnham
Using an atomic force microscope (AFM), we have studied the attractive and adhesive forces between a cantilever tip and sample surfaces as a function of sample surface energy. The measured forces systematically increased with surface energy. The AFM is very sensitive; changes in the surface forces (i.e., attraction and adhesion) of monolayer covered samples could be clearly discerned when only the surface group of the monolayer film was changed from -CH3 to -CF3.