Noncontact atomic force microscopy imaging mechanism on Ag(110): Experiment and first-principles theory

Abstract

In this study, we analyze the noncontact atomic force microscopy ͑NC-AFM͒ imaging mechanism on the Ag͑110͒ surface by experiment and ab initio theory. The experimental NC-AFM images exhibit atomic-scale resolution in the topography and dissipation signal. Interestingly, the maximum of the damping signal is between the maxima of the topography image. Comparing the geometry of the Ag͑110͒ surface with the topography of a simulated NC-AFM image, we found that the first surface layer silver atoms are imaged as maxima in the topographic NC-AFM images. The overall structure and the corrugation height of the theoretical NC-AFM image are in good agreement with the experimental ones. Furthermore, the analysis of the shortrange tip-sample interactions calculated at specific lattice sites revealed strong hysteresis effects. Our simulations also indicate that clean silicon tips might become contaminated with silver atoms during a NC-AFM experiment. Indeed, the NC-AFM experiments showed that the Ag͑110͒ surface is difficult to image probably due to contamination of the silicon tip during the imaging process.

Understanding Dissipative Tip–Molecule Interactions with Submolecular Resolution on an Organic Adsorbate

“…While a general consensus exists in the interpretation of the nc‐AFM topography images, the connection between the dissipation images and some physical energy‐dissipation processes is still very controversial 9, 14–23. Some authors consider van der Waals friction or stochastic friction to be the origin of dissipation while other theoretical models are based on adhesion hysteresis effects 24, –27.…”

Three‐Dimensional Atomic Force Microscopy – Taking Surface Imaging to the Next Level

“…Most often, these frequency shifts Δ f = f ‐ f 0 (where f 0 represents the eigenfrequency of the free cantilever) are compensated by adjusting the z position of the sample, resulting in data sets z ( x , y ) that are said to represent the “topography” of the sample. Since its first successful application for atomic‐scale imaging in 1995,20, 21 FM‐NC‐AFM (subsequently referred to as NC‐AFM) has delivered atomic resolution images of metals,26–28 semiconductors,20, 21, 29–32 and insulators 33–36…”

Atomic resolution on a metal single crystal with dynamic force microscopy

“…4 Although atomic resolution is frequently achieved nowadays, only a comparably small number of atomically resolved images have been presented on metals. [4][5][6] The atomic contrast formation in DFM has since the first days been intensively discussed and analyzed in a number of theoretical as well as experimental publications ͑semiconductors, 7-10 insulators, 11,12 and metals 13,14 ͒. The possibility of atomic resolution is especially desired on heterogeneous systems as for example used in catalysis where metal surfaces might be e.g., partially covered by crystalline oxide surfaces.…”