7 research outputs found
In-situ Raman study of laser-induced graphene oxidation
We present in-situ Raman measurements of laser-induced oxidation in
exfoliated single-layer graphene. By using high-power laser irradiation, we can
selectively and in a controlled way initiate the oxidation process and
investigate its evolution over time. Our results show that the laser-induced
oxidation process is divided into two separate stages, namely tensile strain
due to heating and subsequent -type doping due to oxygen binding. We discuss
the temporal evolution of the -mode ratio during oxidation and explain the
unexpected steady decrease of the defect-induced mode at long irradiation
times. Our results provide a deeper understanding of the oxidation process in
single-layer graphene and demonstrate the possibility of sub-m patterning
of graphene by an optical method.Comment: 5 pages, 4 figures [submitted as IWEPNM 2015 conference publication
to pss(b)
Atomic-Scale Deformations at the Interface of a Mixed-Dimensional van der Waals Heterostructure
Molecular self-assembly due to chemical interactions is the basis of bottom-up nanofabrication, whereas weaker intermolecular forces dominate on the scale of macromolecules. Recent advances in synthesis and characterization have brought increasing attention to two- and mixed-dimensional heterostructures and it has been recognized that van der Waals (vdW) forces within the structure may have a significant impact on their morphology. Here, we suspend single-walled carbon nanotubes (SWCNTs) on graphene to create a model system for the study of a 1D-2D molecular interface through atomic resolution scanning transmission electron microscopy observations. When brought in contact, we observe radial deformation of SWCNTs and the emergence of long-range linear grooves in graphene revealed by three-dimensional reconstruction of the heterostructure. These topographic features are strain-correlated but show no sensitivity to carbon nanotube helicity, electronic structure, or stacking order. Finally, despite random deposition of the nanotubes, we show that the competition between strain and vdW forces results in aligned carbon-carbon interfaces spanning hundreds of nanometers.Peer reviewe
Mitigation of Discordant Rifampicin-Susceptibility Results Obtained by Xpert Mycobacterium tuberculosis/
Atomic-Scale Deformations at the Interface of a Mixed-Dimensional van der Waals Heterostructure
Shia groups and Iranian religious influence in Azerbaijan: the impact of trans-boundary religious ties on national religious policy
Buckyball sandwiches
Two-dimensional (2D) materials have considerably expanded the field of materials science in the past decade. Even more recently, various 2D materials have been assembled into vertical van der Waals heterostacks, and it has been proposed to combine them with other low-dimensional structures to create new materials with hybridized properties. We demonstrate the first direct images of a suspended 0D/2D heterostructure that incorporates C60 molecules between two graphene layers in a buckyball sandwich structure. We find clean and ordered C60 islands with thicknesses down to one molecule, shielded by the graphene layers from the microscope vacuum and partially protected from radiation damage during scanning transmission electron microscopy imaging. The sandwich structure serves as a 2D nanoscale reaction chamber, allowing the analysis of the structure of the molecules and their dynamics at atomic resolution.© The Author
Atomic-Scale Deformations at the Interface of a Mixed-Dimensional van der Waals Heterostructure
Molecular self-assembly due to chemical interactions is the basis of bottom-up nanofabrication, whereas weaker intermolecular forces dominate on the scale of macromolecules. Recent advances in synthesis and characterization have brought increasing attention to two- and mixed-dimensional heterostructures, and it has been recognized that van der Waals (vdW) forces within the structure may have a significant impact on their morphology. Here, we suspend single-walled carbon nanotubes (SWCNTs) on graphene to create a model system for the study of a 1D–2D molecular interface through atomic-resolution scanning transmission electron microscopy observations. When brought into contact, the radial deformation of SWCNTs and the emergence of long-range linear grooves in graphene revealed by the three-dimensional reconstruction of the heterostructure are observed. These topographic features are strain-correlated but show no sensitivity to carbon nanotube helicity, electronic structure, or stacking order. Finally, despite the random deposition of the nanotubes, we show that the competition between strain and vdW forces results in aligned carbon–carbon interfaces spanning hundreds of nanometers.Copyright © 2018 American Chemical Societ