A5044032464- Graphene research and applications
- Molecular Junctions and Nanostructures
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Quantum and electron transport phenomena
- 2D Materials and Applications
- Surface Chemistry and Catalysis
- Synthetic Organic Chemistry Methods
- Chemical Synthesis and Analysis
- Carbon Nanotubes in Composites
- Synthesis and Properties of Aromatic Compounds
- Graphene and Nanomaterials Applications
- Crystallography and molecular interactions
- Topological Materials and Phenomena
- Fullerene Chemistry and Applications
- Covalent Organic Framework Applications
- Nanomaterials for catalytic reactions
- Surface and Thin Film Phenomena
- Organometallic Complex Synthesis and Catalysis
- Advanced Chemical Physics Studies
- Force Microscopy Techniques and Applications
- Nanowire Synthesis and Applications
- Auction Theory and Applications
- Semiconductor materials and devices
- Supercapacitor Materials and Fabrication
University of California System
2025
Lawrence Berkeley National Laboratory
2016-2025
Kavli Energy NanoScience Institute
2016-2025
University of California, Berkeley
2016-2025
Paderborn University
2025
Queen Mary University of London
2019-2024
University of Rome Tor Vergata
2024
Fraunhofer Institute for Reliability and Microintegration
2023
Technische Universität Dresden
1964-2021
Sandia National Laboratories
2020
Observing the intricate chemical transformation of an individual molecule as it undergoes a complex reaction is long-standing challenge in molecular imaging. Advances scanning probe microscopy now provide tools to visualize not only frontier orbitals partners and products, but their internal covalent bond configurations well. We used noncontact atomic force investigate reaction-induced changes detailed structure oligo-(phenylene-1,2-ethynylenes) on (100) oriented silver surface they...
A prerequisite for future graphene nanoribbon (GNR) applications is the ability to fine-tune electronic band gap of GNRs. Such control requires development fabrication tools capable precisely controlling width and edge geometry GNRs at atomic scale. Here we report a technique modifying GNR gaps via covalent self-assembly new species molecular precursors that yields n = 13 armchair GNRs, wider than those previously synthesized using bottom-up techniques. Scanning tunneling microscopy...
Bottom-up synthesized GNRs and GNR heterostructures have promising electronic properties for high performance field effect transistors (FETs) ultra-low power devices such as tunnelling FETs. However, the short length wide band gap of these prevented fabrication with desired switching behaviour. Here, by fabricating channel (Lch ~20 nm) a thin, high-k gate dielectric 9-atom (0.95 armchair material, we demonstrate FETs on-current (Ion >1 uA at Vd = -1 V) Ion/Ioff ~10^5 room temperature. We...
Regulating the complex environment accounting for stability, selectivity, and activity of catalytic metal nanoparticle interfaces represents a challenge to heterogeneous catalyst design. Here we demonstrate intrinsic performance enhancement composite material composed gold nanoparticles (AuNPs) embedded in bottom-up synthesized graphene nanoribbon (GNR) matrix electrocatalytic reduction CO2. Electrochemical studies reveal that structural electronic properties GNR increase AuNP...
Recently developed processes have enabled bottom-up chemical synthesis of graphene nanoribbons (GNRs) with precise atomic structure. These GNRs are ideal candidates for electronic devices because their uniformity, extremely narrow width below 1 nm, atomically perfect edge structure, and desirable properties. Here, we demonstrate nano-scale chemically synthesized GNR field-effect transistors, made possible by development a reliable layer transfer process. We observe strong environmental...
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...
The design and fabrication of robust metallic states in graphene nanoribbons (GNRs) are challenging because lateral quantum confinement many-electron interactions induce electronic band gaps when is patterned at nanometer length scales. Recent developments bottom-up synthesis have enabled the characterization atomically precise GNRs, but strategies for realizing GNR metallicity been elusive. Here we demonstrate a general technique inducing GNRs by inserting symmetric superlattice zero-energy...
The so-called aeg-46.5 region of Escherichia coli contains genes whose expression is induced under anaerobic growth conditions in the presence nitrate or nitrite as terminal electron acceptor. In this work, we have examined more closely several cluster, here designated ccmABCDEFGH, that are homologous to two separate Bradyrhizobium japonicum gene clusters required for biogenesis c-type cytochromes. A deletion mutant E. which lacked all these was constructed. Maturation indigenous cytochromes...
Abstract The thermally induced cyclodehydrogenation reaction of 6,6′‐bipentacene precursors on Au(111) yields peripentacene stabilized by surface interactions with the underlying metallic substrate. STM and atomic‐resolution non‐contact AFM imaging reveal rectangular flakes nanographene featuring parallel pairs zig‐zag armchair edges resulting from lateral fusion two pentacene subunits. synthesis a novel molecular precursor 6,6′‐bipentacene, itself synthetic target interest for optical...
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.
Semiconducting π-conjugated polymers have attracted significant interest for applications in light-emitting diodes, field-effect transistors, photovoltaics, and nonlinear optoelectronic devices. Central to the success of these functional organic materials is facile tunability their electrical, optical, magnetic properties along with easy processability outstanding mechanical associated polymeric structures. In this work we characterize chemical electronic structure individual chains...
The incorporation of nanoscale pores into a sheet graphene allows it to switch from an impermeable semimetal semiconducting nanosieve. Nanoporous graphenes are desirable for applications ranging high-performance semiconductor device channels atomically thin molecular sieve membranes, and their performance is highly dependent on the periodicity reproducibility at atomic level. Achieving precise nanopore topologies in using top-down lithographic approaches has proven be challenging due poor...
The covalent interaction of N-heterocyclic carbenes (NHCs) with transition metal atoms gives rise to distinctive frontier molecular orbitals (FMOs). These emergent electronic states have spurred the widespread adoption NHC ligands in chemical catalysis and functional materials. Although formation carbene-metal complexes self-assembled monolayers on surfaces has been explored, design structure characterization extended low-dimensional NHC-metal lattices remains elusive. Here we demonstrate a...
The cationic molybdenum alkylidyne N-heterocyclic carbene (NHC) complex [Mo(C-p-OMeC6H4)(OCMe(CF3)2)2 (IMes)][B(ArF4] (IMes = 1,3-dimesitylimidazol-2-ylidene) was selectively immobilized inside the pores of ordered mesoporous silica (OMS) with pore diameters 66, 56, and 28 Å used in ring-expansion metathesis polymerization (REMP) cyclic olefins to yield polymers. A strong confinement effect observed for cis-cyclooctene (cCOE), 1,5-cyclooctadiene (COD),...
Finding the right balance: An indole-extended molecular torsion balance has geometry for measuring a truly orthogonal noncovalent interaction between CF bond dipole and an amide carbonyl group (see picture, green F, red O, blue N). Employing double-mutant cycle approach, negative free enthalpies were determined. Thus dipolar interactions can be new tool stabilizing protein–ligand complexes assembling supramolecular architectures.
Orthogonal dipolar interactions between amide C=O bond dipoles are commonly found in crystal structures of small molecules, proteins, and protein-ligand complexes. We herein present the experimental quantification such by employing a model system based on molecular torsion balance. Application thermodynamic double-mutant cycle allows for determination incremental energetic contributions attributed to contact 2 groups. The stabilizing free interaction enthalpies various apolar polar solvents...
We demonstrate the alignment-preserving transfer of parallel graphene nanoribbons (GNRs) onto insulating substrates. The photophysics such samples is characterized by polarized Raman and photoluminescence (PL) spectroscopies. scattered light PL are along GNR axis. cross section as a function excitation energy has distinct excitonic peaks associated with transitions between one-dimensional parabolic subbands. find that GNRs intrinsically low but can be strongly enhanced blue laser irradiation...
Bottom-up graphene nanoribbon (GNR) heterojunctions are nanoscale strips of whose electronic structure abruptly changes across a covalently bonded interface. Their rational design offers opportunities for profound technological advancements enabled by their extraordinary structural and properties. Thus far, the most critical aspect synthesis, control over sequence position along length ribbon, has been plagued randomness in monomer sequences emerging from step-growth copolymerization...