A5032401079- Graphene research and applications
- Molecular Junctions and Nanostructures
- 2D Materials and Applications
- Topological Materials and Phenomena
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Quantum and electron transport phenomena
- Iron-based superconductors research
- Infective Endocarditis Diagnosis and Management
- Cardiac Valve Diseases and Treatments
- Surface and Thin Film Phenomena
- Surface Chemistry and Catalysis
- Cardiac Imaging and Diagnostics
- Force Microscopy Techniques and Applications
- Advanced Materials Characterization Techniques
- Spectroscopy and Quantum Chemical Studies
- Chalcogenide Semiconductor Thin Films
- Radiation Dose and Imaging
- Magnetic properties of thin films
- MXene and MAX Phase Materials
- Metallurgy and Material Forming
- Advanced X-ray and CT Imaging
- Luminescence and Fluorescent Materials
- Covalent Organic Framework Applications
- Advancements in Battery Materials
ExxonMobil (United States)
2024-2025
University of British Columbia
2010-2022
Oak Ridge National Laboratory
2017-2022
Emerald Group Publishing (United Kingdom)
2022
Texas Tech University
2022
Pennsylvania State University
2022
Stanford University
2022
Concordia University
2022
McGill University
2022
York University
2021
Background— Aortic root rupture is a major concern with balloon-expandable transcatheter aortic valve replacement (TAVR). We sought to identify predictors of during TAVR by using multidetector computed tomography. Methods and Results— Thirty-one consecutive patients who experienced left ventricular outflow tract (LVOT)/annular/aortic contained/noncontained were collected from 16 centers. A caliper-matched sample 31 without annular rupture, underwent pre-TAVR tomography served as control...
A fundamental requirement for the development of advanced electronic device architectures based on graphene nanoribbon (GNR) technology is ability to modulate band structure and charge carrier concentration by substituting specific carbon atoms in hexagonal lattice with p- or n-type dopant heteroatoms. Here we report atomically precise introduction group III into bottom-up fabricated semiconducting armchair GNRs (AGNRs). Trigonal-planar B along backbone GNR share an empty p-orbital extended...
A Prospective Evaluation of Dose Reduction and Image Quality in Chest CT Using Adaptive Statistical Iterative ReconstructionJonathon Leipsic1, Giang Nguyen1, Jaqueline Brown1, Don Sin2 John R. Mayo1Audio Available | Share
Substitutional doping of graphene nanoribbons (GNRs) with heteroatoms is a principal strategy to fine-tune the electronic structure GNRs for future device applications. Here, we report fabrication and nanoscale characterization atomically precise N = 13 armchair featuring regioregular edge-doping sulfur atoms (S-13-AGNRs) on Au(111) surface. Scanning tunneling spectroscopy first-principle calculations reveal modification S-13-AGNRs when compared undoped AGNRs.
The magnetic domains in two-dimensional layered material $\mathrm{F}{\mathrm{e}}_{3}\mathrm{GeT}{\mathrm{e}}_{2}$ are studied by using a variable-temperature scanning tunneling microscope with tip after situ cleaving of single crystals. A stripy domain structure is revealed zero-field-cooled sample below the ferromagnetic transition temperature 205 K, which replaced separate double-walled and bubble when cooling under field Ni tip. can further convert to pattern as well move Neel-type chiral...
Direct synthesis of graphene with well-defined nanoscale pores over large areas can transform the fabrication nanoporous atomically thin membranes (NATMs) and greatly enhance their potential for practical applications. However, scalable bottom-up continuous sheets that maintain integrity has not been demonstrated. Here, it is shown a simple reduction in temperature during chemical vapor deposition (CVD) on Cu induces in-situ formation defects (≤2-3 nm) lattice, enabling direct monolayer...
Two-dimensional materials such as layered transition-metal dichalcogenides (TMDs) are ideal platforms for studying defect behaviors, an essential step towards engineering novel material functions. Here, we image the 3D lattice locations of selenium-vacancy V_{Se} defects and manipulate them using a scanning tunneling microscope (STM) near surface PdSe_{2}, recently discovered pentagonal TMD. The show characterisitc charging ring in spatially resolved conductance map, based on which can...
In recent times, the evolution of cationic polymerization has taken a multidirectional approach, with development reversible addition-fragmentation chain transfer (RAFT) polymerization. contrast to conventional methods, which were typically carried out under inert atmospheres and low temperatures, various novel techniques have been developed where reactions are in open air, operate at room temperature, cost-effective, environmentally friendly. Besides, several external stimuli, such as heat,...
The ability to tune the band-edge energies of bottom-up graphene nanoribbons (GNRs) via edge dopants creates new opportunities for designing tailor-made GNR heterojunctions and related nanoscale electronic devices. Here we report local characterization type II composed two different nitrogen edge-doping configurations (carbazole phenanthridine) that separately exhibit electron-donating electron-withdrawing behavior. Atomically resolved structural phenanthridine/carbazole was performed using...
Covalent organic frameworks (COFs) are molecule-based 2D and 3D materials that possess a wide range of mechanical electronic properties. We have performed joint experimental theoretical study the structure boroxine-linked COFs grown under ultrahigh vacuum conditions characterized using scanning tunneling spectroscopy on Au(111) hBN/Cu(111) substrates. Our results show single hBN layer electronically decouples COF from metallic substrate, thus suppressing substrate-induced broadening...
Semiconducting polymer dots (Pdots) have emerged as versatile probes for bioanalysis and imaging at the single-particle level. Despite their utility in multiplexed analysis, deep blue Pdots remain rare due to need high-energy excitation sensitivity photobleaching. Here, we describe design of fluorophores using structural constraints improve resistance photobleaching, two-photon absorption cross sections, fluorescence quantum yields hexamethylazatriangulene motif. Scanning tunneling...
Nanopores attracted a great deal of scientific interest as templates for biological sensors well model systems to understand transport phenomena at the nanoscale. The experimental and theoretical analysis nanopores has been so far focused on understanding effect pore opening diameter ionic transport. In this article we present systematic studies dependence ion properties length. Particular attention was given current rectification exhibited in conically shaped with homogeneous surface...
We report a scanning tunneling microscopy and noncontact atomic force study of close-packed 2D islands tetrafluorotetracyanoquinodimethane (F4TCNQ) molecules at the surface graphene layer supported by boron nitride. While F4TCNQ are known to form cohesive 3D solids, intermolecular interactions that attractive for in repulsive 2D. Our experimental observation molecular behavior on is thus unexpected. This self-assembly can be explained novel solid formation mechanism occurs when charged...
We demonstrate a new method for the detection of spin-chemical potential in topological insulators using spin-polarized four-probe scanning tunneling microscopy on situ cleaved Bi_{2}Te_{2}Se surfaces. Two-dimensional (2D) surface and 3D bulk conductions are separated quantitatively via variable probe-spacing measurements, enabling isolation nonvanishing spin-dependent electrochemical from Ohmic contribution. This component is identified as arising 2D charge current through spin momentum...
Materials exhibiting thermally activated delayed fluorescence (TADF) are now key components of some the most advanced organic light-emitting diodes, photocatalysts, and bioimaging probes. Designing a TADF emitter requires precise understanding its frontier molecular orbitals (FMOs), yet rarely these visualized experimentally. Here, we use scanning tunneling microscopy on Ag(111) to probe electronic structures high-performance materials with different orbital landscapes based s-triazine...
Bottom-up fabrication techniques enable atomically precise integration of dopant atoms into the structure graphene nanoribbons (GNRs). Such dopants exhibit perfect alignment within GNRs and behave differently from bulk semiconductor dopants. The effect concentration on electronic GNRs, however, remains unclear despite its importance in future electronics applications. Here we use scanning tunneling microscopy first-principles calculations to investigate bottom-up synthesized N = 7 armchair...
The atomic and electronic structures of pristine PdSe2 as well various intrinsic vacancy defects in are studied comprehensively by combining scanning tunneling microscopy, spectroscopy, density functional theory calculations. Other than the topmost Se atoms, sublayer Pd atoms identified. Both VSe VPd induce defect states near Fermi level. As a result, can be negatively charged tip gating effect. At negative sample bias, screened Coulomb interaction between microscopy (STM) vacancies creates...
To understand the monomer distribution in copolymers from cationic copolymerization of vinyl ethers (VEs) with 2,3-dihydrofuran (DHF), reactivity ratios VEs (rVE) and DHF (rDHF) were determined. The copolymer compositions calculated 1H NMR spectroscopy, which used to determine extended Kelen-Tüdós (extended K-T) method at high conversion. Furthermore, effect solvent (hexane toluene), temperature (0, −20, −40 °C), Lewis acid (SnCl4 TiCl4) alkyl groups VE monomers (iso-butyl ether (iBVE),...
We report atomically precise pentagonal PdSe2 nanoribbons (PNRs) fabricated on a pristine substrate with hybrid method of top-down and bottom-up processes. The PNRs form uniform array dimer structure width 2.4 nm length more than 200 nm. In situ four-probe scanning tunneling microscopy (STM) reveals metallic behavior ballistic transport for at least 20 in length. Density functional theory calculations produce semiconducting density states isolated find that the band gap narrows disappears...
Defects are ubiquitous in 2D materials and can affect the structure properties of also introduce new functionalities. Methods to adjust density defects during bottom-up synthesis required control growth with tailored optical electronic properties. Here, authors present an Au-assisted chemical vapor deposition approach selectively form SW S2W antisite defects, whereby one or two sulfur atoms substitute for a tungsten atom WS2 monolayers. Guided by first-principles calculations, they describe...
Self-assembly and light-induced mechanical switching of azobenzene derivatives deposited on GaAs(110) were explored at the single molecule level using scanning tunneling microscopy (STM). 3,3′,5,5′-Tetra-tert-butylazobenzene (TTB-AB) molecules in trans isomer configuration found to form well-ordered islands GaAs(110). After exposure ultraviolet (UV) light, TTB-AB exhibited conformational changes attributed cis photoisomerization. Photoisomerization TTB-AB/GaAs is observed occur...