Abstract
Traditionally, atomic force microscopy (AFM) experiments are conducted at tip–sample distances where the tip strongly interacts with the surface. This increases the signal-to-noise ratio, but poses the problem of relaxations in both tip and sample that hamper the theoretical description of experimental data. Here, we employ AFM at relatively large tip–sample distances where forces are only on the piconewton and subpiconewton scale to prevent tip and sample distortions. Acquiring data relatively far from the surface requires low noise measurements. We probed the CaF2(111) surface with an atomically-characterized metal tip and show that the experimental data can be reproduced with an electrostatic model. By experimentally characterizing the second layer of tip atoms, we were able to reproduce the data with 99.5% accuracy. Our work links the capabilities of non-invasive imaging at large tip–sample distances and controlling the tip apex at the atomic scale.
Highlights
When frequency-modulation atomic force microscopy (FM-AFM) first achieved atomic resolution, the attractive forces were on the order of 1 nN [1]
Traditionally, atomic force microscopy (AFM) experiments are conducted at tip–sample distances where the tip strongly interacts with the surface
In traditional FM-AFM, measurements are usually conducted at close tip–sample distances where the tip strongly interacts with the surface to maximize the signal-to-noise ratio
Summary
When frequency-modulation atomic force microscopy (FM-AFM) first achieved atomic resolution, the attractive forces were on the order of 1 nN [1]. In traditional FM-AFM, measurements are usually conducted at close tip–sample distances where the tip strongly interacts with the surface to maximize the signal-to-noise ratio. The idea of greater tip–sample distances to simplify observations and avoid perturbing the sample has far-ranging applications, from a magnetic tip changing the local spin state [13, 14] to measuring a sensitive electronic ground state [15]. These greater distances pose the challenge of acquiring data with piconewton and sub-piconewton force contrast
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
