Hydration Dynamics and the Future of Small-Amplitude AFM Imaging in Air.

Here, we discuss the effects that the dynamics of the hydration layer and other variables, such as the tip radius, have on the availability of imaging regimes in dynamic AFM-including multifrequency AFM. Since small amplitudes are required for high-resolution imaging, we focus on these cases. It is possible to fully immerse a sharp tip under the hydration layer and image with amplitudes similar to or smaller than the height of the hydration layer, i.e., ~1 nm. When mica or HOPG surfaces are only cleaved, molecules adhere to their surfaces, and reaching a thermodynamically stable state for imaging might take hours. During these first hours, different possibilities for imaging emerge and change, implying that these conditions must be considered and reported when imaging.

Rapid discrimination of chemically distinctive surface terminations in 2D material based heterostructures by direct van der Waals identification.

We demonstrate that surfaces presenting heterogeneous and atomically flat domains can be directly and rapidly discriminated via robust intensive quantifiables by exploiting one-pass noninvasive methods in standard atomic force microscopy (AFM), single ∼2 min passes, or direct force reconstruction, i.e., ∼103 force profiles (∼10 min collection time), allowing data collection, interpretation, and presentation in under 20 min, including experimental AFM preparation and excluding only sample fabrication, in situ and without extra experimental or time load. We employ a misfit SnTiS3 compound as a model system. Such heterostructures can be exploited as multifunctional surface systems and provide multiple support sites with distinguishable chemical, mechanical, or opto-electronic distinct properties. In short, they provide an ideal model system to exemplify how current AFM methods can significantly support material discovery across fields.