Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (106)
- Vortrag (99)
- Beitrag zu einem Tagungsband (20)
- Posterpräsentation (18)
- Beitrag zu einem Sammelband (13)
- Buchkapitel (4)
- Sonstiges (2)
- Forschungsdatensatz (2)
- Corrigendum (1)
- Preprint (1)
Sprache
- Englisch (189)
- Deutsch (77)
- Mehrsprachig (1)
Schlagworte
- AFM (11)
- Low energy electrons (7)
- Raman spectroscopy (7)
- Epoxy (6)
- Atomic force microscopy (5)
- Boehmite (5)
- DNA (5)
- Multiphoton lithography (5)
- Cement (4)
- Dosimetry (4)
- Ectoine (4)
- Friction (4)
- Micropatterning (4)
- Nanocomposite (4)
- Nanocomposites (4)
- Nanolithography (4)
- Polydopamine (4)
- Polymer (4)
- Scanning force microscopy (4)
- Stiffness (4)
- Additive manufacturing (3)
- Adhesion (3)
- Aqueous solution (3)
- Compatible solute (3)
- Composites (3)
- Computed tomography (3)
- DNA damage (3)
- DNA radiation damage (3)
- Degradation (3)
- Direct laser writing (3)
- Electron irradiation (3)
- Electron microscopy (3)
- Fire resistance (3)
- Geant4 (3)
- Hydroxyl radicals (3)
- Indium phosphide (3)
- Intermodulation AFM (3)
- Interpenetrating polymer network (3)
- Interphase (3)
- Intumescence (3)
- Mechanical properties (3)
- Microdosimetry (3)
- Nanofibers (3)
- Nanoparticle (3)
- Radiation damage (3)
- Rheology (3)
- SFM/AFM (3)
- Scanning Force Microscopy (3)
- Surface properties (3)
- XPS (3)
- APTES (2)
- Aluminium oxide hydroxide (2)
- Biological structure (2)
- Broadband dielectric spectroscopy (2)
- CNT (2)
- Cancer (2)
- Carbon nanotubes (2)
- Ceramics (2)
- Curing kinetics (2)
- Cytop (2)
- DNA hybridization (2)
- DSC (2)
- Double-strand break (DSB) (2)
- DySEM (2)
- Early hydration (2)
- Ectoin (2)
- Electrical properties (2)
- Energetic material (2)
- Epoxy nanocomposites (2)
- Epoxy resin (2)
- Fast scanning calorimetry (2)
- Femtosecond laser (2)
- Femtosecond laser irradiation (2)
- Fire retardancy (2)
- Functionalization (2)
- Gamma radiation (2)
- Gasfluorierung (2)
- Glass transition temperature (2)
- Hydroxyectoine (2)
- IR (2)
- Interface/interphase (2)
- LET (2)
- Lethal dose (2)
- Microstructure (2)
- Monte Carlo simulation (2)
- Multi photon lithography (2)
- Multiphoton Lithography (2)
- Nanokomposit (2)
- Nanomechanics (2)
- Organic osmolytes (2)
- Oxidation (2)
- PA 66 (2)
- Photobleaching (2)
- Plasmid DNA in water (2)
- Polycarboxylate ether (2)
- Polycarboxylate ether (PCE) (2)
- Pull-out test (2)
- Radiation damage to biomolecules (2)
- Radiation protection (2)
- Radiation therapy (2)
- Radical scavenger (2)
- Raman imaging (2)
- Recycling (2)
- Rigid amorphous fraction (2)
- SZ2080 negative photo-resist (2)
- Salt (2)
- Single-strand break (SSB) (2)
- Solid-phase extraction (2)
- Solutions (pH, salinity, cosolutes) (2)
- TGA (2)
- TGA-MS (2)
- Thermoset (2)
- Titanium (2)
- Two-photon polymerization (2)
- Water structure (2)
- Weathering (2)
- X-ray scattering (2)
- -COOH und NF2-Gruppen (1)
- 1H-NMR (1)
- 2, 4, 6-trinitrophenol (1)
- 2,4,6-trinitrophenol (TNP) (1)
- 266nm (1)
- 2PP (1)
- 3D printing (1)
- 3D-printing (1)
- AFM cantilever vibration (1)
- AFM force distance curves (1)
- AFM force spectroscopy (1)
- AFM friction analysis (1)
- AFM intermittent contact (1)
- AFM plastic deformation (1)
- AFM stiffness of interface (1)
- ATZ (1)
- Abasic site (1)
- Ablation (1)
- Additiv (1)
- Adherends (1)
- Adhesion force (1)
- Adsorption (1)
- Advanced materials (1)
- Aerospace (1)
- Agarose gel electrophorese (1)
- Aging (1)
- Alterung (1)
- Alumina toughened zirconia (1)
- Amino acid (1)
- Analysis and identification (1)
- Analytical Chemistry (1)
- Analytics (1)
- Antimony clusters (1)
- Antimony sulphide (1)
- Aqueous dispersion (1)
- Atomic and Molecular Physics and Optics (1)
- Atomic-scale friction (1)
- Auger electron spectroscopy (1)
- BET (1)
- BNP (1)
- Bench scale fire testing (1)
- Bench-scale fire test (1)
- Bench‐scale fire testing (1)
- Bending modulus (1)
- Bestrahlung (1)
- Bewitterung (1)
- Biomolecules (1)
- Bleaching (1)
- Blockcopolymer (1)
- Boehmit nanoparticle (1)
- Boehmite nanoparticle (1)
- Boehmite nanoparticles (1)
- Bundesoberbehörden (1)
- Böhmit (1)
- C3A (1)
- C3A hydration (1)
- CPD (1)
- Calibration (1)
- Calibration structure (1)
- Cancer therapy (1)
- Cantilever (1)
- Cantilever motion (1)
- Carbon fibre (1)
- Carbon nanotube CNT (1)
- Catheters (1)
- Cationic photocuring (1)
- Cellulose nanofibrils (1)
- Cement hydration (1)
- Central venous access port (1)
- Ceramic nano particles (1)
- Chain scission (1)
- Coating (1)
- Complication (1)
- Composite structures (1)
- Concrete (1)
- Conductivity microscopy (1)
- Cone calorimeter (1)
- Confocal microscopy (1)
- Confocal raman imaging (1)
- Contact interaction (1)
- Contact mechanics (1)
- Coordination polymer (1)
- Copper (1)
- Corrosion (1)
- Counterions (1)
- Crack propagation energy (1)
- Crosslink density control (1)
- Crosslinking density (1)
- Cubic boron nitride (1)
- Cycloaliphatic epoxy oligosiloxane (1)
- DEA (1)
- DET (1)
- DFG (1)
- DMA (1)
- DNA base damage (1)
- DNA immobilization (1)
- DNA melting temperature (1)
- DNA oligonucleotide (1)
- DNA protection (1)
- DNA strand-break (1)
- DNS (1)
- Damage (1)
- Data (1)
- Delayed addition (1)
- Diethylaluminium phosphinate (1)
- Differential scanning calorimetry (1)
- Differential scanning calorimetry (DSC) (1)
- Diffusion barrier (1)
- Direct Laser Writing (1)
- Dispersion (1)
- Domain barriers (1)
- Dynamic ploughing lithography (1)
- EDX (1)
- EPS (1)
- Ectoine DNA interaction (1)
- Ectoine DNA protection (1)
- Ectoine UV absorption (1)
- Ectoine radiation protection (1)
- Ectoine-DNA binding (1)
- Effective irradiation dose 0.2-16 [Gy] (1)
- Eigenmode (1)
- Elasto-plastic response (1)
- Electrohydraulic effect (1)
- Electron irradiation 30 [kV] (1)
- Electron irradiation of DNA (1)
- Electrospinning (1)
- Electrospun nanocomposite fiber (1)
- Energetische Kristalle (1)
- Energiedissipation im Kontakt (1)
- Epoxy conversion degree (1)
- Epoxy resins (1)
- Epoxy-Anhydrid Duroplast (1)
- Excited states (1)
- Exfoliation (1)
- FIB patterning (1)
- FTIR imaging (1)
- FTIRS (1)
- Fabrication parameters (1)
- Faserverbundwerkstoffe (1)
- Femtosecond laser ablation (1)
- Femtosecond laser pulse (1)
- Ferroelectric (1)
- Ferroelectric domain-walls (1)
- Fiber surfaces (1)
- Fiber toxicology (1)
- Films (1)
- Fire behavior (1)
- Fire protective coating (1)
- Fire residue (1)
- Flame retardance (1)
- Flame retarded polymers (1)
- Flammability (1)
- Flash DSC (1)
- Flexible crystals (1)
- Flexural rigidity (1)
- Fluorescence (1)
- Fluorescence imaging (1)
- Fluorescence labeling (1)
- Fluoropolymers (1)
- Force-Microscopy (1)
- Force-displacement curves (1)
- Force-distance curves (1)
- Force-distance-curve (1)
- Force-microscopy (1)
- Forschungsstrategie (1)
- Fs-time resolved microscopy (1)
- Geant4-DNA (1)
- Gel electrophoresis (1)
- Gene-5 protein (1)
- Glas transition temperature (1)
- Glasfaserverstärkter Kunststoff (1)
- Gold (1)
- Grafting (1)
- Graphene (1)
- Graphs (1)
- Grenzfläche als Material (1)
- Guanine content (1)
- HIPS (1)
- HOPG (1)
- Harmonic (1)
- Harmonics (1)
- Harmonix cantilever (1)
- Height Calibration (1)
- Height calibration (1)
- Heterogeneity (1)
- High throughput (1)
- Hot spot (1)
- Hot spot Theorie (1)
- Hot-spot (1)
- Hydration (1)
- Hydroxyl radical (1)
- I/V-characteristics (1)
- Images (1)
- Imaging theory (1)
- In situ near-infrared (NIR) spectroscopy (1)
- Indium Phosphide (1)
- Infrared nano AFM (1)
- Innovative Werkstoffe (1)
- Instability of TNP (1)
- Instrumentation (1)
- Interdiffusion (1)
- Interface/Interphase (1)
- Interface/Interphase Interdiffusion (1)
- Interfacial shear-strength (1)
- Intermodulation (1)
- Intermodulation-AFM (1)
- Interpenetrating polymer networks (1)
- Interphase/interface (1)
- Ionizing radiation (1)
- Knufia petricola (1)
- Kunststoff (1)
- LEE (1)
- LIPSS (1)
- Laser ablation (1)
- Laser direct writing (1)
- Laser induced periodic surface structures (1)
- Laser induced periodic surface structures (LIPSS) (1)
- Laser materials-processing applications (1)
- Laser radiation effects (1)
- Laser writing (1)
- Laser-induced periodic surface structures (LIPSS) (1)
- Layered silicate (1)
- Lead magnoniobate (1)
- Leichtbau (1)
- Linear energy transfer (1)
- Lithography (1)
- Local electrical-properties (1)
- Low voltage SEM (1)
- Low-energy electrons (1)
- Luminescence (1)
- MDFEM (1)
- Magnesium hydroxide (1)
- Magnéli phases (1)
- Material chemistry (1)
- Mathematical model (1)
- Matrix adhesion (1)
- Maxwell-stress microscopy (1)
- Mechanical flexibility (1)
- Mechanical property (1)
- Mechanical testing (1)
- Mechanism of hot-spot formation (1)
- Melanised microcolonial fungi (MCF) (1)
- Meta material (1)
- Metal matrix (1)
- Metal oxide particles (1)
- Microfabrication (1)
- Microplastics (1)
- Microprinting (1)
- Microscopy (1)
- Microscopy (SFM/AFM) thermal diffusivity (1)
- Mikroplastik (1)
- Mikrorissbildung (1)
- Modal analysis (1)
- Modes (1)
- Modulated Lateral Force Microscopy (1)
- Modulated friction techniques (1)
- Molecular dynamics simulation (1)
- Molecular modeling (1)
- Molecular-dynamics (1)
- Monte Carlo (1)
- Morphology analysis (1)
- Motion detection (1)
- Multi-photon light structuring (1)
- Mussel-inspired materials (1)
- NF2-Gruppe (1)
- Nano (1)
- Nano particles (1)
- Nano scale (1)
- Nano-ceramic-additive-manufacturing photoresin (1)
- NanoCAM (1)
- Nanocomposite fibers (1)
- Nanocorrosion of aluminium and silicon (1)
- Nanodots (1)
- Nanolasers (1)
- Nanomanipulation (1)
- Nanomaterialien (1)
- Nanomechanical charecteisation (1)
- Nanomechanical properties (1)
- Nanometer-scale modification (1)
- Nanoparticles (1)
- Nanopartikel (1)
- Nanosafety (1)
- Nanoscale adsorption and desorption (1)
- Nanostructure (1)
- Nanotribology (1)
- Nanoviscosity (1)
- Near-infrared spectroscopy (1)
- Nondestructive testing (1)
- Nonlinearity (1)
- Normung (1)
- OH radicals (1)
- OH scavenger (1)
- OH-radical (1)
- Oberflächenpotential (1)
- Oberflächensteifigkeit (1)
- Open data on zenodo (1)
- Optical breakdown (1)
- Organic crystal (1)
- Organic nanofibers (1)
- Oxide coating (1)
- Oxide-films (1)
- Oxygen-containing functionalities (1)
- PBS (1)
- PFAS (1)
- Para-hexaphenylene (1)
- Para-sexy-phenylene (1)
- Perfluorinated polymer optical fibers (1)
- Phase-transition (1)
- Phenolic resin (1)
- Phosphinates (1)
- Photoconduction (1)
- Picosecond (1)
- Piezo response force microscopy (1)
- Piezoelectric translator (1)
- Piezoresponse (1)
- Plasmid DNA pUC19 (1)
- Plastic deformation (1)
- Plastikstrategie (1)
- Polyamid-6 (1)
- Polybutadiene (1)
- Polycarbonate (1)
- Polyester (1)
- Polyethylene glycol diacrylate (1)
- Polyglycerol (1)
- Polymer coating (1)
- Polymer embedding (1)
- Polymer matrix (1)
- Polymer optical fibers (1)
- Polymer-matrix composites (PMC) scanning/atomic force (1)
- Polymer-matrix composites (PMCs) (1)
- Polymer-matrix composites (PMC´s) (1)
- Polymer-metal (1)
- Polymers (1)
- Powder processing (1)
- Preferential exclusion (1)
- Principle component analysis (1)
- Probing micromechanical properties (1)
- Pull-out (1)
- Pullulan (1)
- Purification (1)
- Pyrolysis (1)
- Quality infrastructure (1)
- Quantification (1)
- Radiation (1)
- Radiation chemistry (1)
- Radiation-induced attenuation (1)
- Radioprotector ectoine (1)
- Raman Spectroscopy (1)
- Real-time infrared spectroscopy (1)
- Recycling-by-design (1)
- Red phosphorus (1)
- Reference material (1)
- Reference structure (1)
- Referenzmaterialien (1)
- Reinforced composites (1)
- Release (1)
- Residue analysis (1)
- Resonance frequency (1)
- Ringversuch (1)
- Risstrajektorie (1)
- Röntgenstreuung (1)
- SEC (1)
- SEM (1)
- SEM/EDX (1)
- SFM (1)
- SSB (1)
- SYBR gold (1)
- Safety (1)
- Samarium (1)
- Scale (1)
- Scanning probe microscope (1)
- Scanning tunneling microscopy (1)
- Scanning/atomic force microscopy (SFM/AFM) (1)
- SchwarzP cells (1)
- Scratching (1)
- Secondary electrons (1)
- Security (1)
- Security labels (1)
- Self-assembled monolayers (1)
- Semiconductor (1)
- Semiconductor materials (1)
- Shear exfoliation (1)
- Shear strength (1)
- Silane (1)
- Silanized DNA (1)
- Silicon monoxide (1)
- Silicone rubber (SiR) (1)
- Simulation (1)
- Simulierte Sonnenstrahlung (1)
- Single crystal metals (1)
- Single stranded DNA (1)
- Slicers (1)
- Slippage of weakly linked layers (1)
- Slurry (1)
- Sodium chloride (1)
- Solid-liquid interfaces (1)
- Solid-state NMR (1)
- Solution plasma (1)
- Spectroscopy (1)
- Spreading resistance microscopy (1)
- Stainless steel (1)
- Standard time temperature furnace (1)
- Structural characterization (1)
- Structural precision (1)
- Structure propertyrelationship (1)
- Structure-property relationship (1)
- Structured cantilever (1)
- Structure–property correlation (1)
- Structure–property relationship (1)
- Sub-aerial biofilms (SAB) (1)
- Sub-micron electrode (1)
- Sun (1)
- Sunscreen (1)
- Superplasticiser (1)
- Superplasticizer (1)
- Surface (1)
- Surface analysis (1)
- Surface functional groups (1)
- Surface reflectivity (1)
- TDS-GC-MS (1)
- TED-GC-MS (1)
- TGA-FTIR (1)
- Tensile test inside a TEM (1)
- Test artifact (1)
- Test structure (1)
- Therapy (1)
- Thermal degradation (1)
- Thermal diffusivity (1)
- Thermoplastic polyurethane (TPU) (1)
- Thermoplastics (1)
- Thermosets (1)
- Thin film (1)
- Time-resolved measurements (1)
- Tip (1)
- Transparency (1)
- Tunneling microscopy (1)
- Two photon polymerisation (1)
- Two photon polymerization (1)
- Two-photon polymerisatio (1)
- Two-photon polymerisation (1)
- Two-photon-polymerization (1)
- UV absorption (1)
- UV irradiation (1)
- UV photons (1)
- UV protection (1)
- UV radiation (1)
- UV-A (1)
- UV-B (1)
- UV-C (1)
- UV-Vis (1)
- Ultra-precision (1)
- Ultrafast optics (1)
- Van der Waals forces (1)
- Vanadium oxide (1)
- Vibration (1)
- Water (1)
- White light interferometry microscopy (1)
- X-ray diffraction (1)
- X-ray photoelectron spectroscopy (1)
- Young´s modulus (1)
- Young’s modulus (1)
- Yttria stabilized zirconia (1)
- Zerstörungsfreie Prüfung (1)
- Zwitterion (1)
- attraktive Wechelwirkung (1)
- g5p protein (1)
- mechanical nonlinearity (1)
- mechanische Nichtlinearitäten (1)
- stl code (1)
- vibration (1)
- α-1,4- and α-1,6-glucans (1)
Organisationseinheit der BAM
- 6 Materialchemie (46)
- 6.6 Physik und chemische Analytik der Polymere (46)
- 6.1 Oberflächen- und Dünnschichtanalyse (9)
- 6.5 Synthese und Streuverfahren nanostrukturierter Materialien (6)
- 5 Werkstofftechnik (4)
- 6.3 Strukturanalytik (3)
- 7 Bauwerkssicherheit (3)
- 7.4 Baustofftechnologie (3)
- 4 Material und Umwelt (2)
- 5.1 Mikrostruktur Design und Degradation (2)
Paper des Monats
- ja (3)
Eingeladener Vortrag
- nein (99)
Rastersondenmikroskopische Verfahren zur Messung lokaler elektrischer Eigenschaften von Festkörpern
(1996)
Two different approaches to investigate the local complex conductivity and the surface charge with Scanning Force Microscopy (SFM) techniques are presented. It is shown that the measurement of local electrical properties with SFM leads to interesting information about the composition of electrically heterogeneous surfaces
Applying a high-frequency lateral vibration between the sample surface and the tip of a scanning force microscope (SFM), a harmonically modulated lateral (friction) force image can be obtained using lock-in techniques. The principles of operation are explained, in particular the dramatic decrease of image artefacts generally caused by topography cross-talk and laser beam interference. Flat interfaces between the two immiscible polymers, poly(methyl methacrylate) (PMMA) and polystyrene (PS), are prepared on a sodium chloride single crystal from the melt. These samples are used to evaluate the appropriate model for the tip-sample interaction geometry. The relationship between frictional and normal force does not follow Amonton's law. This shows that a single-asperity interaction between the tip and sample surface can be considered. Using the new technique, local measurements of shear strength and Young's modulus can be performed.
Low-energy secondary electrons are the most abundant radiolysis species which are thought to be able to attach to and damage DNA via formation and decay of localized molecular resonances involving DNA components. In this study, we analyze the consequences of low-energy electron impact on the ability of DNA to hybridize (i.e., to form the duplex). Specifically, single-stranded thymine DNA oligomers tethered to a gold surface are irradiated with very low-energy electrons (E = 3 eV, which is below the 7.5 eV ionization threshold of DNA) and subsequently exposed to a dye-marked complementary strand to quantify by a fluorescence method the electron induced damage. The damage to (dT)25 oligomers is detected at quite low electron doses with only about 300 electrons per oligomer being sufficient to completely preclude its hybridization. In the microarray format, the method can be used for a rapid screening of the sequence dependence of the DNA-electron interaction. We also show for the first time that the DNA reactions at surfaces can be imaged by secondary electron (SE) emission with both high analytical and spatial sensitivity. The SE micrographs indicate that strand breaks induced by the electrons play a significant role in the reaction mechanism.
Stiffness variation in the interphase of amine-cured epoxy adjacent to copper microstructures
(2007)
In an effort to expand the understanding of the mechanical properties of the polymeric interphase on a metal surface, a composite consisting of epoxy and copper was prepared and analyzed. Scanning force microscopy-based force modulation microscopy (SFM-FMM) was employed along with dynamic mechanical analysis (DMA) and energy dispersive X-ray analysis (EDX). Diglycidyl ether of bisphenol A (DGEBA)-based epoxy resins were applied with amine curing agents. The samples were made taking advantage of electron beam lithography (EBL) in order to produce sharp edges of copper structures and a flat surface suitable for the SFM-FMM analysis, which was able to depict the stiffness within the interphase. It is considered significant information because the mechanical characteristic within the narrow interphase was revealed. Comparing with DMA and EDX, the stiffness information of SFM-FMM demonstrated a matching correlation and agreement in terms of preferential adsorption of the curing agent in the vicinity of the interface. The stiffness profiles of the two epoxy systems turned out to be different, and it shows the material dependence of the interphase characteristics.
Based on an analysis of the diffusive heat flow equation, we determine limits on the localization of heating of soft materials and biological tissues by electromagnetically excited nanoparticles. For heating by rf magnetic fields or heating by typical continuous wave lasers, the local temperature rise adjacent to magnetic or metallic nanoparticles is negligible. However, heat dissipation for a large number of nanoparticles dispersed in a macroscopic region of a material or tissue produces a global temperature rise that is orders of magnitude larger than the temperature rise adjacent to a single nanoparticle. One approach for producing a significant local temperature rise on nanometer length scales is heating by high-power pulsed or modulated lasers with low duty cycle.
Applying a high-frequency lateral vibration between tip and sample in a scanning force microscope (SFM), a harmonically modulated lateral (friction) force image can be obtained using lock-in techniques. Harmonically modulated lateral force microscopy (HM-LFM) offers several advantages compared with standard lateral force microscopy (LFM). After a brief investigation of the scan velocity dependence of LFM and HM-LFM, two samples were investigated. First, the surface of a poly(acrylonitrile-co-styrene)/polybutadiene blend (ABS) was used to demonstrate the ability of the new technique to decrease the stick effects of the SFM tip. Second, an interface between two chemically very similar polymers was prepared by melting polypropylene (PP) and poly(propene-block-ethene) (PP-block-PE) films on each other. After cutting, the surface roughness of this sample was very high. It is shown that only HM-LFM clearly resolves the local micromechanical properties without artefacts.
Force-displacement curves have been obtained with a commercial atomic force microscope (AFM) at different temperatures and probe rates on a thick film of poly(n-butyl methacrylate) (PnBMA). The analysis of the force-displacement curves has been focused on the contact portion of the curves, giving information about the stiffness of the sample and its Young's modulus. A novel model of sample deformations that extends the basic equations of the elastic continuum contact theories to the plastic deformations is presented. This model gives several insights into the processes of deformation of soft samples and permits to calculate not only the parameters of the Williams-Landel-Ferry equation but also the Young's modulus and the yielding force of the polymer as a function of temperature and/or probe rate. These quantities have been measured in a wide range of temperatures (70 K) and probe rates (6 decades) for the first time with the AFM, and the results are in very good agreement with measurements performed with customary techniques, such as broadband spectroscopy and dynamic mechanical analysis.
The use of a fibre-based light sensor for the calibration of Scanning Probe Microscopy piezos
(1999)
The irradiation of single-crystalline indium phosphide (c-InP) by Ti:sapphire femtosecond laser pulses (130 fs, 800 nm) in air is studied by means of in-situ time resolved reflectivity measurements [fs-time-resolved microscopy (100 fs-10 ns) and point probing analysis (ns - µs)] and by complementary ex-situ surface analytical methods (Micro Raman Spectroscopy, Scanning Force, and Optical Microscopy). The dynamics of melting, ablation, and optical breakdown as well as structural changes resulting from rapid solidification are investigated in detail. Different laser-induced surface morphologies are characterized and discussed on the basis of recent ablation and optical breakdown models.
A stoichiometric amineepoxy formulation was cured in the presence of a thermoplastic, namely poly(vinylpyrrolidone) (PVP). The epoxy system consisted of the resin diglycidyl ether of bisphenol A (DGEBA) and the aromatic curing agent 4,4'-diaminodiphenylsulfone (DDS). As shown for this system in a former study by Oyama et al. [Oyama HT, Lesko JJ, Wightman JP. J Polym Sci B 1997;35:33146. [36]], preferential absorption of amine molecules by PVP can occur. In the present study, the focus is on the variations of local elastic properties within the epoxy interphase adjacent to the PVP layer. The curing was performed close to the glass transition temperature, Tα, of the PVP film, namely at 170 °C. Variations of the local amine concentration were tracked using energy-dispersive analysis of X-rays (EDX), by taking benefit of the sulfur contained in DDS. Using temperature-dependent dynamic mechanical analysis (DMA), a series of epoxy reference samples of different amineepoxy concentration ratios, r, was investigated in order to work out the relationship between r and the epoxy storage modulus at room temperature. In the excess-epoxy regime, r<1, the modulus is observed to increase with departure from the stoichiometric ratio, r=1. Considering the respective suppression of the ß-transition, the observed characteristic can be explained by an antiplasticisation effect. Depth-sensing indentation (DSI) experiments across the epoxy/PVP interphase provided evidence for strong modulus variations. In consistency with the EDX and the DMA data, in the vicinity of the PVP layer the local epoxy modulus is increased. The total change of the epoxy Young's modulus is ~1.1 GPa. However, the total width of the modulus decay of ~175 µm is ~2.5 times larger than the one of the DDS concentration gradient. This finding is discussed in terms of additional spatial variations of the DGEBA concentration as well as long-range diffusion currents of DDS induced by the interdiffusion processes and their effect on the final network of crosslinks.
A specially designed scanning force microscope (SFM, atomic force microscope – AFM) was incorporated into the chamber of a commercial scanning electron microscope (SEM) to investigate vibrating SFM cantilevers at their resonance. Inherently, the spatial resolution of electron microscopy is higher than that of optical methods. In this paper we present vibration modes (eigenmodes) of two different SFM cantilevers. Their nonlinear behavior is also explored in order to depict their 2nd harmonics (twice the fundamental frequency). Imaging of the local vibration is performed by measuring the frequency- and phase-selective responses of the SE signal at different X and Y positions of the scanned electron beam.
In this work, reactive magnetron-sputtered Pb(Zr,Ti)O3 thin films were used to fabricate well-ordered nanodot arrays by means of nanosphere lithography (NSL). NSL is based on a two-step etch process by means of, firstly adjusting the diameter of polystyrene spheres in the self-assembled polymeric nanosphere mask using reactive ion etching, and secondly transferring the mask to the substrate by ion milling with adjusted heights. Hence, structures with different aspect ratios can be fabricated.
Piezoresponse force microscopy was used as the inspection tool on both non-patterned and patterned films. Both the topography and polarization out of plane and in plane was deduced in this mode. Grains of nanodots with low aspect ratio form domain structures comparable to domains in non-patterned films. In contrast to that, nanodots with a higher aspect ratio form particular structures. The in-plane amplitude images show mostly a bisectioned domain assembly, while the out-of-plane amplitude images show in some cases more complex structures like 'c'-shaped domains or multi-domains around a center domain.
The patterning of the ferroelectric material was shown to affect the formation of ferroelectric domains. The initial polycrystalline, randomly-ordered films are re-oriented and show domain structures depending on nanodisc diameter and aspect ratio. This may enable tailoring of ferroelectric materials in their piezoelectric and pyroelectric properties by patterning.
We report surface plasmon resonance (spr) and confocal fluorescence results concerning the interaction of a gene-5-protein (g5p) with single-stranded DNA oligonucleotides (dT25) tethered to a gold surface. The spr data show that a highly stable g5pssDNA complex is readily formed on a gold surface with koff = 1.7 × 10-3 s-1. The extent of the complexion indicated involvement of the cooperative proteinprotein interactions within the binding to DNA. In the experiments where dT25 coexist with g5p in the solution, the fluorescence data show that g5p also mediates the binding between the non-complementary oligonucleotides in the solution and those immobilised on the surface.
Observation of nanoscale hot-spot generation on a 2, 4, 6-trinitrophenol (TNP) single crystal
(2011)
An energetic material (EM) creates a local thermal point when it accepts energy and the EM will explode due to thermal decomposition when the hot-spot temperature reaches the explosive temperature. The initial stage of the hot-spot formation on 2, 4, 6-trinitrophenol (TNP) single crystal has been observed at the nanometer scale using atomic force microscopy (AFM). The hot-spot generation has been directly initiated by means of an AFM tip. The phenomenon is accompanied by producing agglomerated spherical-like nanoparticles due to a low-temperature decomposition of TNP. It has been observed that the agglomerated particles are produced outside of the stimulated region. The observed decomposition process at the nanoscale doesn't lead to a self-sustaining shock as detonation or explosion. The results are of interest in relation to explore the origin of deformation-induced chemical decomposition or detonation of EM.
We use a dynamic scanning electron microscope (DySEM) to analyze the movement of oscillating micromechanical structures. A dynamic secondary electron (SE) signal is recorded and correlated to the oscillatory excitation of scanning force microscope (SFM) cantilever by means of lock-in amplifiers. We show, how the relative phase of the oscillations modulate the resulting real part and phase pictures of the DySEM mapping. This can be used to obtain information about the underlying oscillatory dynamics. We apply the theory to the case of a cantilever in oscillation, driven at different flexural and torsional resonance modes. This is an extension of a recent work (Schr¨oter et al 2012 Nanotechnology 23 435501), where we
reported on a general methodology to distinguish nonlinear features caused by the Imaging process from those caused by cantilever motion.
Beyond measuring the topography of surfaces, scanning force microscopy (SFM) has proved to be valuable both for mapping of various materials properties and for modifying surfaces via lithography techniques. Thus, SFM has gained relevance as a surface analysis technique as well as a tool for nanoscale engineering purposes. Different kinds of tip-sample interactions are exploitable, e.g. mechanical, thermal and electrical ones. Owing to its versatility, SFM has found plenty of applications in polymer science. Among others, the examples reported on in this review article encompass issues related to commodity polymers, various polymer-based composites, polymer blends, or ferroelectric polymers. For instance, stiffness imaging is elucidated as a technique for detecting interphases occurring in composites with inorganic fillers. The described applications are mainly related to mechanical and electrical tip-sample interactions. The respective fundamentals are outlined as well as some aspects of the measurement of materials contrasts. The presented techniques of nano-scale modification are a dynamical sort of plowing lithography and electrical poling, both performed by means of SFM-probes.
Rastersondenverfahren
(2003)
An AFM-ESEM Hybride
(2003)
Thin polyamide-6 films were exposed to fluorine gas and analysed with photoelectron and infrared spectroscopies. Fluorine cleaves the amide CN bond resulting in the formation of the COOH and NF2 terminal groups. This is evident from large shifts in the N1s binding energy (+5 eV) and C=O stretching frequency (~80 cm-1), appearance of ester oxygen in the XPS spectra, as well as by the 19F nmr spectra of volatile products consistent with a terminal NF2 group.
Dynamic Plowing Lithography
(2001)
The Normal Force Modulation as a method for Studying the Interphase of Fibre Reinforced Polymer
(1998)
Laminates of carbon fiber reinforced plastic (CFRP), which are manufactured by injection technology, are reinforced with boehmite particles. This doping strengthens the laminates, whose original properties are weaker than those of prepregs. Besides the shear strength, compression strength and the damage tolerance, the mode of action of the nanoparticles in resin and in CFRP is also analyzed. It thereby reveals that the hydroxyl groups and even more a taurine modification of the boehmites' surface alter the elementary polymer morphology. Consequently a new flow and reaction comportment, lower glass transition temperatures and shrinkage, as well as a changed mechanical behavior occur. Due to a structural upgrading of the matrix (higher shear stiffness, reduced residual stress), a better fiber-matrix adhesion, and differing crack paths, the boehmite nanoparticles move the degradation barrier of the material to higher loadings, thus resulting in considerably upgraded new CFRP.
For the first time, we report the direct observation of the nanoscale adsorption and desorption of 2,4,6-trinitrophenol (TNP) molecules on the crystal surface during atomic force microscopy scanning. Our results reveal the position instability of TNP molecules at the border of molecular layers under normal ambient conditions. The observed phenomena are of great interest for exploring the origin of hot-spot generation on the surface of energetic materials. On the basis of the explored properties of TNP crystal, a plausible mechanism of hot-spot formation upon weak initiation at the nanoscale is proposed.
Analytical and numerical analysis of imaging mechanism of dynamic scanning electron microscopy
(2012)
The direct observation of small oscillating structures with the help of a scanning electron beam is a new approach to study the vibrational dynamics of cantilevers and microelectromechanical systems. In the scanning electron microscope, the conventional signal of secondary electrons (SE, dc part) is separated from the signal response of the SE detector, which is correlated to the respective excitation frequency for vibration by means of a lock-in amplifier. The dynamic response is separated either into images of amplitude and phase shift or into real and imaginary parts. Spatial resolution is limited to the diameter of the electron beam. The sensitivity limit to vibrational motion is estimated to be sub-nanometer for high integration times. Due to complex imaging mechanisms, a theoretical model was developed for the interpretation of the obtained measurements, relating cantilever shapes to interaction processes consisting of incident electron beam, electron–lever interaction, emitted electrons and detector response. Conclusions drawn from this new model are compared with numerical results based on the Euler–Bernoulli equation.
Energetische Materialien enthalten gespeicherte chemische Energie. Diese potentielle Energie kann bei Zündung schlagartig als Strahlungsenergie und Druckerhöhung freigesetzt werden. Nanoskalige Komponenten erhöhen zusätzlich die innere Energie des Materials um den Beitrag der Oberflächenenergie und verbessern die chemische Umsetzung durch bessere Durchmischung. Die hot-spot-Theorie zur Zündung von Explosivstoffen kombiniert mechanische Stimulation und einer dabei zu erreichenden Schwellwert-Energie mit der Temperatur. Wird die Energie zum exothermen Bindungsbruch etwa beim Reibvorgang erreicht entsteht auf der molekularen Skala ein hot-spot. Der Stoff explodiert, wenn der hot-spot ausreichend lange besteht, sich verstärkt und nicht durch Energiedissipation (Festkörperschallausbreitung, Wärmediffusion) verzehrt wird.
Rasterkraftmikroskopie (AFM atomic force microscopy) dient nicht nur zur bildgebenden Vermessung der Topographie und der mechanischen Eigenschaften, sondern kann auch zur gezielten Veränderung der Oberflächen verwendet werden. Solche lithographischen Verfahren bedienen sich im AFM-Kontaktmodus (Scratching Lithography) direkt der Reibung, im hochfrequenten intermittierenden Kontaktverfahren realisiert man einen vibrierenden Kontaktes (Dynamic Plowing Lithography), der beim Eindringen in eigenen Indentationseindruck reibt. In beiden Fällen überträgt man durch Kombination einer Scherbewegung mit einer Variation des Kontaktdrucks Energie auf die Oberfläche, was nachweislich zum chemischen Bindungsbruch z.B. auf Polymeroberflächen führt. Zwei kristalline Explosivstoffe werden untersucht und sowohl dissipative Effekte als auch die Generierung eines hot-spots demonstriert.
The ultra–precision cutting of steel materials is possible but needs modifications of machine tools or the workpiece material. One approach of actual research is the development of cutting materials that gives the opportunity for direct cutting of surfaces with ultra–precision quality. Binderless–cBN is here one of the most promising materials. The paper shows results of experimental studies with binderless–cBN as cutting material while turning stainless steel. Various investigations were carried out to determine the wear mechanisms. Furthermore, measurements are shown regarding the surface quality. The achieved results show the high potential ofbinderless–cBN as cutting material for the machining of steel.
Femtosecond time-resolved microscopy has been used to analyze the structural transformation dynamics (melting, ablation, and solidification phenomena) induced by single intense 130 fs laser pulses in single-crystalline (100)-indium phosphide wafers in air on a time scale from ~100 fs up to 8 ns. In the ablative regime close to the ablation threshold, transient surface reflectivity patterns are observed by fs microscopy on a ps to ns time scale as a consequence of the complex spatial density structure of the ablating material (dynamic Newton fringes). At higher fluences, exceeding six times the ablation threshold, optical breakdown causes another, more violent ablation regime, which reduces the energy deposition depth along with the time of significant material removal. As a consequence, ablation lasts longer in a ring-shaped region around the region of optical breakdown. This leads to the formation of a crater profile with a central protrusion. In the melting regime below the ablation threshold, the melting dynamics of indium phosphide has been quantified and subsequent superficial amorphization has been observed upon solidification on the ns time scale leading to amorphous layer thicknesses of the order of a few tens of nanometers.
The pyrolysis and fire behavior of glass-fiber reinforced poly(butylene terephthalate) (PBT/GF) with two different metal phosphinates as flame retardants in combination with and without melamine cyanurate (MC) were analyzed by means of thermogravimetry, thermogravimetry coupled with infrared spectroscopy, flammability, and cone calorimeter tests as well as scanning electron microscopy/energy dispersive X-ray spectroscopy and X-ray fluorescence spectroscopy. In PBT/GF, dosages of 13-20% of the halogen-free flame retardant aluminum phosphinate or aluminum phosphinate in combination with MC fulfill the requirements for electrical engineering and electronics applications (UL 94 = V-0; LOI > 42%), whereas the use of the same amount of zinc phosphinate or zinc phosphinate in combination with MC does not improve the fire behavior satisfactorily (UL 94 = HB; LOI = 27-28%). The performance under forced flaming conditions (cone calorimeter) is quite similar for both of the metal phosphinates. The use of aluminum and zinc salts results in similar flame inhibition predominantly due to the release of the phosphinate compounds in the gas phase. Both metal phosphinates and MC interact with the polymer changing the decomposition characteristics. However, part of the zinc phosphinate vaporizes as a complete molecule. Because of the different decomposition behavior of the metal salts, only the aluminum phosphinate results in a small amount of thermally stable carbonaceous char. In particular, the aluminum phosphinate-terephthalate formed is more stable than the zinc phosphinate-terephthalate. The small amount of char has a crucial effect on the thermal properties and mechanical stability of the residue and thus the flammability.
Modulated lateral force microscopy: an AFM tool for analysis and modification of polymer surfaces
(2007)
Modulated lateral force microscopy: An AFM tool for analysis and modification of polymer surfaces
(2007)
Rasterkraftmikroskopische Verfahren zur Beschreibung der Grenzflächen in Polymer-Kompositwerkstoffen
(2010)
Von makroskopischen Fragestellungen und mikroskopischen Untersuchungsmethoden in der Tribologie
(2010)
Modulated lateral force microscopy: an AFM tool for analysis and modification of polymer surfaces
(2007)
Para-hexaphenylene (p-6P) molecules exhibit a characteristic photoinduced reaction (bleaching) resulting in a decrease in luminescence intensity upon UV light exposure, which could render the technological use of the nanofibers problematic. In order to investigate the photoinduced reaction in nanofibers, optical bleaching experiments have been performed by irradiating both pristine and coated nanofibers with UV light. Oxide coating materials (SiOx and Al2O3) were applied onto p-6P nanofibers. These treatments caused a reduction in the bleaching reaction but in addition, the nanofiber luminescence spectrum was significantly altered. It was observed that some polymer coatings [a statistical copolymer of tetrafluoroethylene and 2,2-bis-trifluoromethyl-4,5-difluoro-1,3-dioxole, P(TFE-PDD), and poly(methyl methacrylate), PMMA] do not interfere with the luminescence spectrum from the p-6P but are not effective in stopping the bleaching. Bilayer coatings with first a polymer material, which should work as a protection layer to avoid modifications of the p-6P luminescence spectrum, and second an oxide layer used as oxygen blocker were tested and it was found that a particular bilayer polymer/oxide combination results in a significant reduction in bleaching without affecting significantly the emission spectrum from the nanofibers.