Noncontact Atomic Force Microscopy for Atomic-Scale Characterization of Material Surfaces

Abstract

Among the large variety of scanning probe microscopy techniques, noncontact atomic force microscopy (NC-AFM) stands out with its capability of atomicresolution imaging and spectroscopy measurements on conducting, semiconducting as well as insulating sample surfaces. In this chapter, we review the fundamental experimental and instrumental methodology associated with the technique and present key results obtained on different classes of material surfaces. In addition to atomic-resolution imaging, the use of NC-AFM towards the goal of atomic-resolution force spectroscopy is emphasized.

True Atomic-Resolution Surface Imaging and Manipulation under Ambient Conditions via Conductive Atomic Force Microscopy

“…Specifically, Figure C shows a current image recorded on PtSe 2 (001) , where the atomic surface structure together with several atomic-scale defects (indicated by white arrows) can be resolved. Much like early NC-AFM images recorded on Si (111)-7 × 7, this image features frequent changes in contrast that can be attributed to minute alterations in the tip apex that occur during scanning: e.g., by transfer of atoms or molecules to/from the sample surface …”

Photo induced force microscopy: chemical spectroscopy beyond the diffraction limit

“…under vacuum for example which, not only maintains a surface in its pristine state, 77 but also prevents surface water layers and photothermally induced acoustic waves, which, as O'Callahan et al discuss can have a detrimental effect on the cantilever. 78 However, carrying out PiFM measurements in vacuum incurs other problems, including increased impact of the photothermal effect arising from the cantilever absorbing scattered light giving a vibration with a different phase to the photoinduced force.…”

“…PiFM is a relatively new technology, and its capabilities are rapidly improving, including increasing spatial resolution, sensitivity, and conditions under which the technique can operate. Some relatively simple methods have been suggested to increase the quality of PiFM imaging, carrying out measurements under vacuum for example which, not only maintains a surface in its pristine state, 77 but also prevents surface water layers and photothermally induced acoustic waves, which, as O’Callahan et al discuss can have a detrimental effect on the cantilever. 78 However, carrying out PiFM measurements in vacuum incurs other problems, including increased impact of the photothermal effect arising from the cantilever absorbing scattered light giving a vibration with a different phase to the photoinduced force.…”

Adaptive Time-Resolved Mass Spectrometry with Nanomechanical Resonant Sensors

“…The implementation of the proposed scheme is best accomplished in the sampled-data domain. In order to lead to a digital implementation, we discretize time in (9) with a time-step of h to obtain…”