Beyond Topography: The Path towards Robust, Quantitative, Multidimensional Atomic Resolution Imaging with Chemical Selectivity

Abstract

Despite the evolution of scanning probe microscopy (SPM) into a powerful set of techniques that image surfaces and map their properties down to the atomic level, significant limitations in both imaging and mapping persist. Currently, typical SPM capabilities qualitatively record only one property at a time and at a fixed distance from the surface. Furthermore, the probing tip’s apex is chemically and electronically undefined, complicating data interpretation. In this talk, we will review recent extensions to existing SPM approaches that provide information beyond simple topography. We start with expanding vacuum-based high-resolution noncontact atomic force microscopy, which can provide two-dimensional images revealing the sample’s atomic structure, to three dimensions by adding the capability to quantify the tip-sample force fields near a surface with picometer and piconewton resolution. Next, we show how electronic and topographic information can be combined by recording the tunneling current simultaneously with the force interaction, and introduce a new operating scheme called tuned-oscillator atomic force microscopy that substantially improves imaging robustness and therefore sample throughput and user friendliness. Finally, we will illustrate how the tip chemistry, tip asymmetry, and tip-sample distance influence the recorded interactions – and thus the information one can gain from images –, ultimately allowing to resolve the internal structure of molecules or selectively image specific atomic species. During the talk, applications to various model systems including oxides, metals, ionic crystals, and layered materials will be presented.