Search results for "scanning tunneling microscopy"
showing 10 items of 21 documents
Lateral Fusion of Chemical Vapor Deposited N = 5 Armchair Graphene Nanoribbons
2017
Bottom-up synthesis of low-bandgap graphene nanoribbons with various widths is of great importance for their applications in electronic and optoelectronic devices. Here we demonstrate a synthesis of N = 5 armchair graphene nanoribbons (5-AGNRs) and their lateral fusion into wider AGNRs, by a chemical vapor deposition method. The efficient formation of 10- and 15- AGNRs is revealed by a combination of different spectroscopic methods, including Raman and UV−visnear-infrared spectroscopy as well as by scanning tunneling microscopy. The degree of fusion and thus the optical and electronic properties of the resulting GNRs can be controlled by the annealing temperature, providing GNR films with o…
On-surface Synthesis of a Chiral Graphene Nanoribbon with Mixed Edge Structure.
2020
Abstract Chiral graphene nanoribbons represent an important class of graphene nanomaterials with varying combinations of armchair and zigzag edges conferring them unique structure‐dependent electronic properties. Here, we describe the on‐surface synthesis of an unprecedented cove‐edge chiral GNR with a benzo‐fused backbone on a Au(111) surface using 2,6‐dibromo‐1,5‐diphenylnaphthalene as precursor. The initial precursor self‐assembly and the formation of the chiral GNRs upon annealing are revealed, along with a relatively small electronic bandgap of approximately 1.6 eV, by scanning tunnelling microscopy and spectroscopy.
Odorant binding changes the electrical properties of olfactory receptors at the nanoscale
2021
Olfactory receptors (ORs) comprise the largest multigene family in the vertebrates. They belong to the class A (rhodopsin-like) family of G protein-coupled receptors (GPCRs), which are the most abundant membrane proteins, having widespread, significant roles in signal transduction in cells, and therefore, they are a major pharmacological target. Moreover, ORs displayed high selectivity and sensitivity towards odorant detection, a characteristic that raised the interest for developing biohybrid sensors based on ORs for the detection of volatile compounds. The transduction of odorant binding into cellular signaling by ORs is not well understood and knowing its mechanism would enable developin…
Optical properties of biocompatible polyaniline nano-composites
2006
Abstract Polyaniline (PANI) is an electro-active polymer of great interest thanks to its outstanding physical and chemical properties which make it suitable for various applications in optics, bioelectronics, biosensors, diagnostics and therapeutic devices. Unfortunately, PANI is infusible and insoluble in most common solvents and, thus, very difficult to process. In the attempt of improving processability, yet preserving its interesting properties, PANI has been synthesized in the form of particles and dispersed into a hydrogel matrix. The synthesis of PANI–hydrogel composites proceeds via γ-irradiation of PANI dispersions as obtained by ‘in situ’ polymerization of aniline in the presence …
Atomic-scale magnetic domain walls in quasi-one-dimensional Fe nanostripes.
2001
Fe nanostripes on W(110) are investigated by Kerr magnetometry and spin-polarized scanning tunneling microscopy (SP-STM). An Arrhenius law is observed for the temperature dependent magnetic susceptibility indicating a one-dimensional magnetic behavior. The activation energy for creating antiparallel spin blocks indicates extremely narrow domain walls with a width on a length scale of the lattice constant. This is confirmed by imaging the domain wall by SP-STM. This information allows the quantification of the exchange stiffness and the anisotropy constant.
Moir\'e-enabled topological superconductivity
2020
The search for artificial topological superconductivity has been limited by the stringent conditions required for its emergence. As exemplified by the recent discoveries of various correlated electronic states in twisted van der Waals materials, moir\'e patterns can act as a powerful knob to create artificial electronic structures. Here, we demonstrate that a moir\'e pattern between a van der Waals superconductor and a monolayer ferromagnet creates a periodic potential modulation that enables the realization of a topological superconducting state that would not be accessible in the absence of the moir\'e. The magnetic moir\'e pattern gives rise to Yu-Shiba-Rusinov minibands and periodic mod…
Spin-polarized scanning tunneling microscopy and spectroscopy of ultrathinFe∕Mo(110)films usingW∕Au∕Cotips
2006
We report on magnetic contrast observed in low-temperature spin-polarized scanning tunneling microscopy (SP-STM) of Fe nanowires deposited on Mo(110) using tungsten tips covered by $\mathrm{Au}∕\mathrm{Co}$ thin films. Due to the spin reorientation transition of Co films on Au an out-of-plane magnetic sensitivity is obtained for tips with thin cobalt films (up to 8 monolayers of Co), while for thicker Co coverages an in-plane magnetization component can be probed. Using $\mathrm{W}∕\mathrm{Au}∕\mathrm{Co}$ tips with out-of-plane magnetic sensitivity we show that the one (ML) and two (DL) atomic layers thick Fe nanowires prepared using step flow growth on a Mo(110) crystal are perpendicularl…
Temperature-driven spin reorientation transition inFe∕Mo(110)nanostructures
2007
Using low-temperature spin polarized scanning tunneling microscopy and spectroscopy, we observed a temperature-driven spin-reorientation transition (SRT) in Fe double layer (DL) nanostructures grown by step-flow growth on Mo(110). Magnetization components along the vertical and horizontal directions were detected with $4∕16$ ML Co∕10 ML $\mathrm{Au}∕\mathrm{W}(110)$ tips with out-of-plane (4 ML Co) and in-plane (16 ML Co) magnetic sensitivities. The magnetic easy axis of the Fe DL nanostructures continuously rotates from the vertical direction at $5\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ to an in-plane direction at $20\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The rotation angle is independent …
Electronic structure of MgO-supported Au clusters: quantum dots probed by scanning tunneling microscopy.
2007
We investigate via density functional theory (DFT) the appearance of small MgO-supported gold clusters with 8 to 20 atoms in a scanning tunneling microscope (STM) experiment. Comparison of simulations of ultrathin films on a metal support with a bulk MgO leads to similar results for the cluster properties relevant for STM. Simulated STM pictures show the delocalized states of the cluster rather than the atomic structure. This finding is due to the presence of s- derived delocalized states of the cluster near the Fermi energy. The properties of theses states can be understood from a jellium model for monovalent gold.
Deformation-Free Topography from Combined Scanning Force and Tunnelling Experiments
1993
We show that by measuring force and stiffness on a constant-current scanning tunnelling microscopy (STM) contour a deformation-free topography can be extracted. With reference to mono- and bicomponent self-assembled monolayers, we find that the characteristic depression pattern and the protrusions on a multicomponent film found in STM are to a great extent due to electronic effects.