A5074145338- Conducting polymers and applications
- Molecular Junctions and Nanostructures
- Organic Electronics and Photovoltaics
- Graphene research and applications
- Fullerene Chemistry and Applications
- Analytical Chemistry and Sensors
- Organic Light-Emitting Diodes Research
- Boron and Carbon Nanomaterials Research
- Spectroscopy and Quantum Chemical Studies
- Quantum and electron transport phenomena
- Photochemistry and Electron Transfer Studies
- Advanced Physical and Chemical Molecular Interactions
- Diamond and Carbon-based Materials Research
- Mechanical and Optical Resonators
- Organic and Molecular Conductors Research
- Carbon Nanotubes in Composites
- Advanced Chemical Physics Studies
- Force Microscopy Techniques and Applications
- Surface Chemistry and Catalysis
- Metal and Thin Film Mechanics
- Electrochemical Analysis and Applications
- Synthesis and Properties of Aromatic Compounds
- Semiconductor materials and devices
- Surface and Thin Film Phenomena
- Transition Metal Oxide Nanomaterials
Linköping University
2011-2025
KU Leuven
2010
Institut de Ciència de Materials de Barcelona
2010
University of Mons
1989-2010
Thinfilm (Sweden)
2008
Honeywell (United States)
2002
Max Planck Institute for Polymer Research
2000
Universidade Federal de Juiz de Fora
1998
University of Namur
1987-1988
We present optical-absorption data together with band-structure calculations for the polaron lattice and bipolaron highly conducting form of polyaniline, proton-doped polyemeraldine. show that polaron-lattice band structure fully accounts observed optical transitions. These results are in marked contrast electronic other doped polymers, only one single broad appears deep gap a very narrow nearly degenerate conduction-band edge.
${\mathrm{CN}}_{x}$ films were found to have a distorted graphitelike microstructure consisting of buckled and curved basal planes using high-resolution electron microscopy. Nanoindentation showed an elastic recovery 85%, hardness $\ensuremath{\sim}60$ GPa. Based on detailed quantum chemical calculations photoelectron spectroscopy, the observed structure is proposed consist network ${\mathrm{sp}}^{2}$-hybridized planes, cross-linked by ${\mathrm{sp}}^{3}$-hybridized bonds. The buckling shown...
We use a band unfolding technique to recover an effective primitive cell picture of the structure graphene under influence different types perturbations. This involves intrinsic perturbations, such as structural defects, and external ones, comprising nitrogen substitutions inclusion in adsorbed systems. In cases, provides reliable efficient tool for quantitatively analyzing effect doping defects on electronic graphene. envision that this approach will become standard method computational...
We show that the spectral weights $W_{m\vec K}(\vec k)$ used for unfolding of two-component spinor eigenstates $| {\psi_{m\vec K}^\mathrm{SC}} > = | \alpha {\psi_{m\vec{K}}^\mathrm{SC, \alpha}} + \beta \beta}} >$ can be decomposed as sum partial $W_{m\vec{K}}^{\mu}(\vec calculated each component $\mu \alpha, \beta$ independently, effortlessly turning a possibly complicated problem involving two coupled quantities into independent problems easy solution. Furthermore, we define...
We computationally study the reaction mechanisms of halogen-based covalent self-assembly, a major route for synthesizing molecular nanostructures and nanographenes on surfaces. Focusing biphenyl as small model system, we describe dehalogenation, recombination, diffusion processes. The kinetics different processes are also investigated, in particular how coupling barriers affect recombination rates. Trends across periodic table derived from three commonly used close-packed (111) surfaces (Cu,...
Rare crystal phases that expand in one or more dimensions when hydrostatically compressed are identified and shown to have negative Poisson's ratios. Some of these crystals (i) decrease volume two stretched a particular direction (ii) increase surface area compressed. Possible mechanisms for achieving such linear compressibilities described single composites, sensor applications proposed. Materials with properties may be used fabricate porous solids either all directions penetrating fluid...
We report a new fullerenelike material consisting of cross-linked nano-onions C and N. Growth the onion shells takes place atom by on substrate surface yields thin solid films during magnetron sputter deposition. Electron microscopy energy loss spectroscopy show that core shell contains up to $20\mathrm{at}.%$ N corresponding ${\mathrm{C}}_{48}{\mathrm{N}}_{12}$ aza-fullerene composition. Nanoindentation this nanostructured gives high resilience with hardness 7 GPa, Young's modulus 37...
We investigate the cooperative effects controlling synthesis of a graphene nanoribbon on Au(111) surface starting from an anthracene polymer using density functional calculations including van der Waals interactions. focus high-temperature cyclodehydrogenation step reaction and find that proceeds by simultaneously transferring two H-atoms units to Au surface, leaving behind C-C bond in process. This is significantly more favorable than three other potential paths. Moreover, we successive...
The harmonic oscillator model of aromaticity (HOMA) offers a straightforward route to quantifying that requires no other information than the bond lengths conjugated ring in question. Given such is often readily obtainable from quantum-chemical calculations, it pertinent improve this parametrized as much possible. Here, new version HOMA presented where, atypically, corresponding parameters are derived actual both aromatic and antiaromatic (rather nonaromatic) reference compounds, calculated...
The motion of excitations such as polarons is believed to be fundamental importance for the transport properties conjugated polymers use in, e.g., polymer based LED's. We have investigated polaron dynamics in a system coupled chains presence an external electric field. In particular, we focus on how migrates through lattice, i.e., situation which reaches chain end and scattered surrounding chains. show that outcome this event strongly depends strength field, identify three different cases migration.
We have investigated the chemical nature and electronic structure of interface between a low work function metal, aluminum, conjugated polymer semiconductor, polythiophene. studied initial stages formation by depositing metal onto surface film. Charge transfer processes are analyzed using core-level x-ray photoelectron spectroscopy (XPS); evolution upon metallization valence levels directly related to is followed with ultraviolet (UPS). With these techniques, we investigate deposition...
Band-structure calculations are presented for different lattice conformations of doped polyacetylene and polythiophene. At intermediate doping levels, the intraband transition energies found to be in good agreement with experimental optical-absorption data a soliton conformation bipolaron high where both polymers exhibit metalliclike behavior, we find best observed magnetic occur polaron conformation. Important qualitative differences between obtained this work those reported previously. The...
The electronic structure of tris(8-hydroxyquinoline) aluminum (Alq3) has been studied in the pristine molecular solid state as well upon interaction (doping) with potassium and lithium. We discuss results a joint theoretical experimental investigation, based on combination x-ray ultraviolet photoelectron spectroscopies quantum-chemical calculations at density functional theory level. Upon doping, each electron transferred from an alkali metal atom is stored one three ligands Alq3 molecule,...
Polaron drift in an external electric field and the dynamics following insertion of electron have been simulated a one-dimensional conjugated polymer chain. The simulations were performed by solving time-dependent Schr\"odinger equation lattice motion simultaneously nonadiabatically. We observed step-like transition from sonic to supersonic polaron velocities around strength $0.14\phantom{\rule{0.3em}{0ex}}\text{mV}∕\mathrm{\AA{}}$. This behavior is be directly related decoupling acoustic...
Ultraviolet photoelectron spectroscopy (UPS) has been used to observe changes in the \ensuremath{\pi}-band structure poly(3-hexylthiphene) induced by doping using ${\mathrm{NOPF}}_{6}$. The charge-induced movement of Fermi energy and a finite density electronic states at most highly doped (saturated) material are seen unambiguously with UPS for first time conjugated polymer. results imply existence new, recently predicted theoretically, but hitherto unobserved, polaron-lattice state this...
A synthetic strategy was developed for the preparation of porphyrins containing between one and four stereogenic centers, such that their molecular weights vary only as a result methyl groups which give chiral forms. The low-dimensional nanoscale aggregates these compounds reveal profound effects this varying chirality on supramolecular structure optical activity. number centers influences significantly self-assembly porphyrin molecules described here. scanning tunneling microscopy study...
The mechanism of the newly reported route for surface-assisted covalent coupling terminal alkynes on Ag(111) is unraveled by density functional theory based transition state calculations. We illustrate that reaction path fundamentally different from classical schemes in wet chemistry. It initiated between two molecules instead single-molecule dehydrogenation. silver substrate found to play an important role stabilizing intermediate species chemical bonds, although it hardly active...
A molecular model system of tetraphenyl porphyrins (TPP) adsorbed on metallic substrates is systematically investigated within a joint scanning tunnelling microscopy/molecular modelling approach. The conformation TPP molecules, their adsorption gold surface and the growth highly ordered islands are modelled with combination density functional theory dynamic force field methods. results indicate subtle interplay between different contributions. molecule–substrate interaction causes bending...
The schematic visualization of the Alq3 moleculeon Fe substrate with optimized geometry at lowest total energy. When molecule is relaxed on surface, only two wings are lying down and third wing remains perpendicular to showing a strong hybridization occurance. Detailed facts importance specialist readers published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset. They made available submitted by authors. Please note: publisher responsible for content...
Density functional theory (DFT) calculations were performed in order to investigate the stability and electronic structure of graphene-gold interfaces. Two configurations studied: a gold cluster interacting with graphene different polycyclic aromatic hydrocarbon (PAH) molecules, namely, C${}_{6}$H${}_{6}$ (benzene), C${}_{24}$H${}_{12}$ (coronene), C${}_{54}$H${}_{18}$ (circumcoronene) adsorbed on an Au(111) surface. Nonlocal interactions accounted for by using semiempirical DFT-D2 method...