4 research outputs found
Behavior of Kinesin Driven Quantum Dots Trapped in a Microtubule Loop
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>i.e.</i>, about 70 Ī¼m, 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
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Self-Assembly Strategy for Fabricating Connected Graphene Nanoribbons
We use self-assembly to fabricate and to connect precise graphene nanoribbons end to end. Combining scanning tunneling microscopy, Raman spectroscopy, and density functional theory, we characterize the chemical and electronic aspects of the interconnections between ribbons. We demonstrate how the substrate effects of our self-assembly can be exploited to fabricate graphene structures connected to desired electrodes
Precursor Geometry Determines the Growth Mechanism in Graphene Nanoribbons
On-surface
synthesis with molecular precursors has emerged as the
de facto route to atomically well-defined graphene nanoribbons (GNRs)
with controlled zigzag and armchair edges. On Au(111) and Ag(111)
surfaces, the prototypical precursor 10,10ā²-dibromo-9,9ā²-bianthryl
(DBBA) polymerizes through an Ullmann reaction to form straight GNRs
with armchair edges. However, on Cu(111), irrespective of the bianthryl
precursor (dibromo-, dichloro-, or halogen-free bianthryl), the Ullmann
route is inactive, and instead, identical chiral GNRs are formed.
Using atomically resolved noncontact atomic force microscopy (nc-AFM),
we studied the growth mechanism in detail. In contrast to the nonplanar
BA-derived precursors, planar dibromoperylene (DBP) molecules do form
armchair GNRs by Ullmann coupling on Cu(111), as they do on Au(111).
These results highlight the role of the substrate, precursor shape,
and moleculeāmolecule interactions as decisive factors in determining
the reaction pathway. Our findings establish a new design paradigm
for molecular precursors and opens a route to the realization of previously
unattainable covalently bonded nanostructures