Search

While offering high resolution atomic and electronic structure, scanning probe microscopy techniques have found greater challenges in providing reliable electrostatic characterization on the same scale. In this work, we offer electrostatic discovery atomic force microscopy, a machine learning based method which provides immediate maps of the electrostatic potential directly from atomic force microscopy images with functionalized tips. We apply this to characterize the electrostatic properties of a variety of molecular systems and compare directly to reference simulations, demonstrating good agreement. This approach offers reliable atomic scale electrostatic maps on any system with minimal computational overhead.

According to Hückel theory, an anti-aromatic molecule possessing (4n)π-electrons becomes unstable. Although the stabilization has been demonstrated by radialene-type structures-fusing aromatic rings to anti-aromatic rings-in solution, such molecules have never been studied at a single molecular level. Here, we synthesize a cyclobutadiene derivative, dibenzo[b,h]biphenylene, by an on-surface intramolecular reaction. With a combination of high-resolution atomic force microscopy and density functional theory calculations, we found that a radialene structure significantly reduces the anti-aromaticity of the cyclobutadiene core, extracting π-electrons, while the small four-membered cyclic structure keeps a high density of the total charge.

We report the observation of kinesin driven quantum dots (QDs) trapped in a microtubule loop, allowing the investigation of moving QDs for a long time and an unprecedented long distance. The QD conjugates did not depart from our observational field of view, enabling the tracking of specific conjugates for more than 5 min. The unusually long run length and the periodicity caused by the loop track allow comparing and studying the trajectory of the kinesin driven QDs for more than 2 full laps, i.e., about 70 μm, enabling a statistical analysis of interactions of the same kinesin driven object with the same obstacle. The trajectories were extracted and analyzed from kymographs with a newly developed algorithm. Despite dispersion, several repetitive trajectory patterns can be identified. A method evaluating the similarity is introduced allowing a quantitative comparison between the trajectories. The velocity variations appear strongly correlated to the presence of obstacles. We discuss the reasons making this long continuous travel distances on the loop track possible.