scholarly journals Insights into the physical chemistry of materials from advances in HAADF-STEM

2015 ◽  
Vol 17 (6) ◽  
pp. 3982-4006 ◽  
Author(s):  
Karl Sohlberg ◽  
Timothy J. Pennycook ◽  
Wu Zhou ◽  
Stephen J. Pennycook
Keyword(s):  
Physical Chemistry ◽  
Real Space ◽  
Atomic Resolution ◽  
Dopant Atom ◽  
Chemical Identification ◽  
Graphene Lattice

HAADF-STEM provides atomic-resolution real space imaging. Here an image of a single Si dopant atom in a graphene lattice is shown adjacent to a schematic of the instrument. Simultaneous EELS on electrons scattered to low angles can provide chemical identification of the species preset. Differences between the Si L-edge spectra reveal differences in atomic bonding and hybridization for different configurations of Si atoms in graphene.

scholarly journals Disorder induced lifetime effects in binary disordered systems: A first principles formalism and an application to disordered graphene

2017 ◽  
Vol 31 (29) ◽  
pp. 1750218 ◽  
Author(s):  
Banasree Sadhukhan ◽  
Subhadeep Bandyopadhyay ◽  
Arabinda Nayak ◽  
Abhijit Mookerjee
Keyword(s):  
Green Function ◽  
First Principles ◽  
Disordered Systems ◽  
Random Distribution ◽  
Real Space ◽  
Recursion Method ◽  
Resonant States ◽  
Graphene Lattice ◽  
Lifetime Effects ◽  
Local Defects

In this work, the conducting properties of graphene lattice with a particular concentration of defect (5% and 10%) has been studied. The real space block recursion method introduced by Haydock et al. has been used in presence of the random distribution of defects in graphene. This Green function based method is found to be more powerful than the usual reciprocal based methods which need artificial periodicity. Different resonant states appear because of the presence of topological and local defects are studied within the framework of Green function.

scholarly journals Towards chemical identification in atomic-resolution noncontact AFM imaging with silicon tips

2003 ◽  
Vol 68 (19) ◽  
Author(s):  
A. S. Foster ◽  
A. Y. Gal ◽  
J. M. Airaksinen ◽  
O. H. Pakarinen ◽  
Y. J. Lee ◽  
...  
Keyword(s):  
Atomic Resolution ◽  
Chemical Identification ◽  
Afm Imaging ◽  
Noncontact Afm

Atomic resolution imaging using the real-space distribution of electrons scattered by a crystalline material

2011 ◽  
Vol 67 (5) ◽  
pp. 487-490 ◽  
Author(s):  
Sorin Lazar ◽  
Joanne Etheridge ◽  
Christian Dwyer ◽  
Bert Freitag ◽  
Gianluigi A. Botton
Keyword(s):  
Real Space ◽  
Crystalline Material ◽  
Atomic Resolution ◽  
Space Distribution ◽  
The Real ◽  
Resolution Imaging

scholarly journals Real-space localization and quantification of hole distribution in chain-ladder Sr3Ca11Cu24O41 superconductor

2016 ◽  
Vol 2 (3) ◽  
pp. e1501652 ◽  
Author(s):  
Matthieu Bugnet ◽  
Stefan Löffler ◽  
David Hawthorn ◽  
Hanna A. Dabkowska ◽  
Graeme M. Luke ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Physical Properties ◽  
Inelastic Scattering ◽  
Cuprate Superconductors ◽  
Scanning Transmission Electron Microscope ◽  
Real Space ◽  
Atomic Scale ◽  
Atomic Resolution ◽  
Space Localization ◽  
Chain Ladder

Understanding the physical properties of the chain-ladder Sr3Ca11Cu24O41 hole-doped superconductor has been precluded by the unknown hole distribution among chains and ladders. We use electron energy-loss spectrometry (EELS) in a scanning transmission electron microscope (STEM) at atomic resolution to directly separate the contributions of chains and ladders and to unravel the hole distribution from the atomic scale variations of the O-K near-edge structures. The experimental data unambiguously demonstrate that most of the holes lie within the chain layers. A quantitative interpretation supported by inelastic scattering calculations shows that about two holes are located in the ladders, and about four holes in the chains, shedding light on the electronic structure of Sr3Ca11Cu24O41. Combined atomic resolution STEM-EELS and inelastic scattering calculations is demonstrated as a powerful approach toward a quantitative understanding of the electronic structure of cuprate superconductors, offering new possibilities for elucidating their physical properties.

Chemical identification at atomic resolution on Cu(110)-O surface using NC-AFM

2015 ◽  
Vol 45 (1) ◽  
pp. 017002-017002
Author(s):  
Jun LIU ◽  
ChenYang XUE ◽  
ZongMin MA ◽  
Jun TANG ◽  
YunBo SHI ◽  
...  
Keyword(s):  
Atomic Resolution ◽  
Chemical Identification

Accurate Nanoscale Crystallography in Real-Space Using Scanning Transmission Electron Microscopy

2015 ◽  
Vol 21 (4) ◽  
pp. 946-952 ◽  
Author(s):  
J. Houston Dycus ◽  
Joshua S. Harris ◽  
Xiahan Sang ◽  
Chris M. Fancher ◽  
Scott D. Findlay ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Density Functional ◽  
Building Blocks ◽  
Real Space ◽  
Atomic Resolution ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

AbstractHere, we report reproducible and accurate measurement of crystallographic parameters using scanning transmission electron microscopy. This is made possible by removing drift and residual scan distortion. We demonstrate real-space lattice parameter measurements with <0.1% error for complex-layered chalcogenides Bi2Te3, Bi2Se3, and a Bi2Te2.7Se0.3 nanostructured alloy. Pairing the technique with atomic resolution spectroscopy, we connect local structure with chemistry and bonding. Combining these results with density functional theory, we show that the incorporation of Se into Bi2Te3 causes charge redistribution that anomalously increases the van der Waals gap between building blocks of the layered structure. The results show that atomic resolution imaging with electrons can accurately and robustly quantify crystallography at the nanoscale.

scholarly journals Atomic resolution tracking of nerve-agent simulant decomposition and host metal–organic framework response in real space

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Maxwell W. Terban ◽  
Sanjit K. Ghose ◽  
Anna M. Plonka ◽  
Diego Troya ◽  
Pavol Juhás ◽  
...  
Keyword(s):  
Function Analysis ◽  
Theoretical Calculations ◽  
Metal Organic Framework ◽  
Chemical Warfare Agents ◽  
Nerve Agent ◽  
Real Space ◽  
Atomic Resolution ◽  
Agent Interaction ◽  
Warfare Agents ◽  
Metal Organic

AbstractGas capture and sequestration are valuable properties of metal–organic frameworks (MOFs) driving tremendous interest in their use as filtration materials for chemical warfare agents. Recently, the Zr-based MOF UiO-67 was shown to effectively adsorb and decompose the nerve-agent simulant, dimethyl methylphosphonate (DMMP). Understanding mechanisms of MOF-agent interaction is challenging due to the need to distinguish between the roles of the MOF framework and its particular sites for the activation and sequestration process. Here, we demonstrate the quantitative tracking of both framework and binding component structures using in situ X-ray total scattering measurements of UiO-67 under DMMP exposure, pair distribution function analysis, and theoretical calculations. The sorption and desorption of DMMP within the pores, association with linker-deficient Zr6 cores, and decomposition to irreversibly bound methyl methylphosphonate were directly observed and analyzed with atomic resolution.

High-resolution structure determination by ALCHEMI

1983 ◽  
Vol 41 ◽  
pp. 178-181 ◽  
Author(s):  
Peter G. Self ◽  
Peter R. Buseck
Keyword(s):  
Site Occupancy ◽  
Real Space ◽  
Unit Cell ◽  
Bragg Angle ◽  
Electron Current ◽  
High Resolution Structure ◽  
Beam Incident ◽  
Crystallographic Planes ◽  
Electron Beam Incident ◽  
Resolution Structure

ALCHEMI (Atom Location by CHanneling Enhanced Microanalysis) enables the site occupancy of atoms in single crystals to be determined. In this article the fundamentals of the method for both EDS and EELS will be discussed. Unlike HRTEM, ALCHEMI does not place stringent resolution requirements on the microscope and, because EDS clearly distinguishes between elements of similar atomic number, it can offer some advantages over HRTEM. It does however, place certain constraints on the crystal. These constraints are: a) the sites of interest must lie on alternate crystallographic planes, b) the projected charge density on the alternate planes must be significantly different, and c) there must be at least one atomic species that lies solely on one of the planes.An electron beam incident on a crystal undergoes elastic scattering; in reciprocal space this is seen as a diffraction pattern and in real space this is a modulation of the electron current across the unit cell. When diffraction is strong (i.e., when the crystal is oriented near to the Bragg angle of a low-order reflection) the electron current at one point in the unit cell will differ significantly from that at another point.

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