A5086588675- NMR spectroscopy and applications
- Rheology and Fluid Dynamics Studies
- Nuclear Physics and Applications
- Polymer Surface Interaction Studies
- Block Copolymer Self-Assembly
- Atomic and Subatomic Physics Research
- Force Microscopy Techniques and Applications
- Material Dynamics and Properties
- X-ray Diffraction in Crystallography
- Polymer crystallization and properties
- Seismic Imaging and Inversion Techniques
- Enhanced Oil Recovery Techniques
- Spectroscopy and Quantum Chemical Studies
- Surface Modification and Superhydrophobicity
- Advanced ceramic materials synthesis
- Blood properties and coagulation
- Characterization and Applications of Magnetic Nanoparticles
- High-pressure geophysics and materials
- Quantum, superfluid, helium dynamics
- Advanced NMR Techniques and Applications
- Surfactants and Colloidal Systems
- Lipid Membrane Structure and Behavior
- Phase Equilibria and Thermodynamics
- High-Velocity Impact and Material Behavior
- ZnO doping and properties
Uppsala University
2013-2022
Montanuniversität Leoben
2017
Neutron scattering techniques offer several unique opportunities in materials research. However, most neutron experiments suffer from the limited flux available at current facilities. This limitation becomes even more severe if time-resolved or kinetic are performed. A new method has been developed which overcomes these limitations when a reversible process is studied, without any compromise on resolution beam intensity. It demonstrated that, by recording absolute time detector events linked...
Shear responsive surfaces offer potential advances in a number of applications. Surface functionalization using polymer brushes is one route to such properties, particularly the case entangled polymers. We report on neutron reflectometry measurements solutions performed under controlled shear as well coarse-grained computer simulations corresponding these interfaces. Here we show reversible and reproducible collapse brushes, increasing with rate. Using two greatly different chain lengths...
We have applied small angle scattering in grazing incidence beam geometry on a time-of-flight neutron instrument. Due to the broad wavelength distribution provided for specific incident penetration depth of is varied over range single measurement. The near surface structure polymer micelles close silicon substrates with distinct energy resolved. It observed that very near-surface strongly depends coating whereas further away from bulk like ordering found. A more pronounced found surfaces high energy.
We report the detection and quantification of nuclear spin incoherent scattering from hydrogen occupying interstitial sites in a thin film vanadium. The neutron wave field is enhanced quantum resonator with magnetically switchable boundaries. Our results provide pathway for study dynamics at surfaces ultrathin films using inelastic and/or quasielastic methods.
Neutron Spin Echo spectroscopy provides unique insight into molecular and submolecular dynamics as well intra- inter-molecular interactions in soft matter. These may change drastically under shear flow. In particular polymer physics a stress plateau is observed, which might be explained by an entanglement-disentanglement transition. However, such transition difficult to identify directly experiments. has been proven provide information about entanglement length degree probing the local of...
Reflectivity measurements offer unique opportunities for the study of surfaces and interfaces, specular reflectometry has become a standard tool in materials science to resolve structures normal surface thin film. Off-specular scattering, which probes lateral structures, is more difficult analyse, because Fourier space being probed highly anisotropic scattering pattern truncated by interface. As result, patterns collected with (especially time-of-flight) neutron reflectometers are transform...
Grazing incidence neutron scattering experiments offer surface sensitivity by reflecting from an interface at momentum transfers close to total external reflection. Under these conditions the penetration depth is strongly non-linear and may change many orders of magnitude. This fact imposes severe challenges for resolved experiments, since brilliance beams relatively low in comparison e.g. synchrotron radiation. In this article we use probability density functions calculate contribution...
Neutron scattering experiments are a unique tool in material science due to their sensitivity light elements and magnetic induction. However, for kinetic studies the low brilliance at existing sources poses challenges. In case of periodic excitations these challenges can be overcome by binning signal according excitation state sample. To advance into this direction we have performed polarised time resolved grazing incidence neutron measurements on an aqueous solution polymer F127 mixed with...
Self-consistent field approach is used to model a single end-tethered polymer chain on substrate subject various forces in three dimensions. Starting from continuous Gaussian model, the following perturbations are considered: (i) hydrodynamic interaction with an externally imposed shear flow for which alternative theoretical framework formulated; (ii) excluded volume effect good solvent, treated mean approximation; (iii) monomer-substrate repulsion. While stretches along flow, change of...
Entangled polymers are deformed by a strong shear flow. The shape of the polymer, called form factor, is measured small angle neutron scattering. However, real-space molecular structure not directly available from reciprocal-space data, due to phase problem. Instead, data has be fitted with theoretical model molecule. We approximate unknown using piecewise straight segments, which we derive an analytical factor. fit it our on semi-dilute entangled polystyrene solution under in situ character...
The influence and interaction of the ionizable amphiphilic drug amitriptyline hydrochloride (AMT) on a 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) phospholipid bilayer supported silica surface have been investigated using combination neutron reflectometry quartz crystal microbalance with dissipation monitoring. Adding AMT solutions concentrations 3, 12, 50 mM leaves lipid mainly intact we observe most molecules attached to head-group region outer leaflet. Virtually no penetrates into...
We present in-situ neutron spin echo measurements on an entangled polydimethylsiloxane melt under shear and demonstrate the ability to monitor nano-scale dynamics in flowing liquids. report no changes topological interactions of chains for rates approaching inverse longest relaxation time. Further experiments following along this line will allow systematically test predictions theories, like e.g. convective constraint release.