Measurement of the Gold-Gold Bond Rupture Force at 4 K in a Single-Atom Chain Using Photon-Momentum-Based Force Calibration
We present instrumentation and methodology for simultaneously measuring force and displacement at the atomic scale at 4 K. The technique, which uses a macroscopic cantilever as a force sensor and high-resolution, high-stability fiber-optic interferometers for displacement measurement, is particularly well-suited to making accurate, traceable measurements of force and displacement in nanometer- and atomic-scale mechanical deformation experiments. The technique emphasizes accurate co-location of force and displacement measurement and measures cantilever stiffness at the contact point in situ at 4 K using photon momentum. We present preliminary results of measurements made of the force required to rupture a single atomic bond in a gold single-atom chain formed between a gold flat and a gold tip. Finally, we discuss the possible use of the gold-gold bond rupture force as an intrinsic force calibration value for forces near 1 nN.
The authors gratefully acknowledge the many DFT calculations performed by Francesca Tavazza, Lyle Levine, and Anne Chaka; those calculations were invaluable in the interpretation of the experimental results. This work was funded in part by the Innovations in Measurement Science program at the National Institute of Standards and Technology.
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