scholarly journals Depth-resolved grazing-incidence time-of-flight neutron scattering from a solid–liquid interface

2013 ◽  
Vol 47 (1) ◽  
pp. 130-135 ◽  
Author(s):  
M. Wolff ◽  
J. Herbel ◽  
F. Adlmann ◽  
A. J. C. Dennison ◽  
G. Liesche ◽  
...  
Keyword(s):  
Time Of Flight ◽  
Incident Beam ◽  
Grazing Incidence ◽  
Near Surface ◽  
Beam Geometry ◽  
Angle Scattering ◽  
Wide Range ◽  
Specific Incident ◽  
Liquid Boundary ◽  
Solid Liquid

Small-angle scattering in grazing-incidence beam geometry has been applied on a time-of-flight neutron instrument to investigate a solid–liquid boundary. Owing to the broad wavelength distribution provided for a specific incident beam angle, the penetration depth of the neutron beam is varied over a wide range in a single measurement. The near surface structures of block copolymer micelles close to silicon substrates with distinct surface energies are resolved. It is observed that the very near surface structure strongly depends on the surface coating, whereas further away from the surface, bulk-like ordering is found.

scholarly journals Surface distortion of Fe dot-decorated TiO2 nanotubular templates using time-of-flight grazing incidence small angle scattering

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Neelima Paul ◽  
Jean-Francóis Moulin ◽  
Gaetano Mangiapia ◽  
Armin Kriele ◽  
Peter Müller-Buschbaum ◽  
...  
Keyword(s):  
Small Angle ◽  
Time Of Flight ◽  
Surface Region ◽  
Grazing Incidence ◽  
Morphological Properties ◽  
Ferromagnetic Behavior ◽  
Sem Images ◽  
Near Surface ◽  
Correlation Lengths ◽  
Surface Distortion

AbstractPhysical properties of nanoclusters, nanostructures and self-assembled nanodots, which in turn are concomitantly dependent upon the morphological properties, can be modulated for functional purposes. Here, in this article, magnetic nanodots of Fe on semiconductor TiO2 nanotubes (TNTs) are investigated with time-of-flight grazing incidence small-angle neutron scattering (TOF-GISANS) as a function of wavelength, chosen from a set of three TNT templates with different correlation lengths. The results are found corroborating with the localized scanning electron microscopy (SEM) images. As we probe the inside and the near-surface region of the Fe-dotted TNTs with respect to their homogeneity, surface distortion and long-range order using TOF-GISANS, gradual aberrations at the top of the near-surface region are identified. Magnetization measurements as a function of temperature and field do not show a typical ferromagnetic behavior but rather a supermagnetic one that is expected from a nonhomogeneous distribution of Fe–dots in the intertubular crevasses.

Application of a single-reflection collimating multilayer optic for X-ray diffraction experiments employing parallel-beam geometry

2008 ◽  
Vol 41 (1) ◽  
pp. 124-133 ◽  
Author(s):  
M. Wohlschlögel ◽  
T. U. Schülli ◽  
B. Lantz ◽  
U. Welzel
Keyword(s):  
Incident Beam ◽  
Grazing Incidence ◽  
Photon Flux ◽  
Data Sets ◽  
Parallel Beam ◽  
X Ray ◽  
Beam Focusing ◽  
Beam Geometry ◽  
Parallel Beam Geometry ◽  
Diffraction Patterns

Instrumental aberrations of a parallel-beam diffractometer equipped with a rotating anode X-ray source, a single-reflection collimating multilayer optic and a parallel-plate collimator in front of the detector have been investigated on the basis of standard measurements (i.e.employing stress- and texture-free isotropic powder specimens exhibiting small or negligible structural diffraction line broadening). It has been shown that a defocusing correction, which is a major instrumental aberration for diffraction patterns collected with divergent-beam (focusing) geometries, is unnecessary for this diffractometer. The performance of the diffractometer equipped with the single-reflection collimating multilayer optic (single-reflection mirror) is compared with the performance of the diffractometer equipped with a Kirkpatrick–Baez optic (cross-coupled Göbel mirror) on the basis of experimental standard measurements and ray-tracing calculations. The results indicate that the use of the single-reflection mirror provides a significant gain in photon flux and brilliance. A high photon flux, high brilliance and minimal divergence of the incident beam make the setup based on the single-reflection mirror particularly suitable for grazing-incidence diffraction, and thus for the investigation of very thin films (yielding low diffracted intensities) and of stress and texture (requiring the acquisition of large measured data sets, corresponding to the variation of the orientation of the diffraction vector with respect to the specimen frame of reference). A comparative discussion of primary optics which can be used to realise parallel-beam geometry shows the range of possible applications of parallel-beam diffractometers and indicates the virtues and disadvantages of the different optics.

scholarly journals Exploring Hidden Local Ordering in Microemulsions with a Weak Directive Second Order Parameter

2020 ◽  
Vol 3 (3) ◽  
pp. 703-709 ◽  
Author(s):  
Michael Kerscher ◽  
Frederik Lipfert ◽  
Henrich Frielinghaus
Keyword(s):  
Order Parameter ◽  
Capillary Condensation ◽  
Grazing Incidence ◽  
Near Surface ◽  
Correlation Lengths ◽  
Shear Rates ◽  
Surface Ordering ◽  
Scalar Order Parameter ◽  
Solid Liquid Interface ◽  
Solid Liquid

Abstract So far, the near-surface ordering of microemulsions was focused on lamellar ordering while the bulk microemulsion was bicontinuous. In a series of different non-ionic surfactants the near-surface ordering of microemulsions at a hydrophilic silicon surface was studied using grazing incidence small angle neutron scattering. For the surfactant C8E3, most likely a gyroid structure was found at the solid–liquid interface, while the more efficient surfactants find lamellar ordering up to lamellar capillary condensation. The ranges for near-surface ordering are deeper than the bulk correlation lengths. These findings point towards theories that use directional order parameters that would lead to deeper near-surface ordering than simple theories with a single scalar order parameter would predict. Rheology experiments display high viscosities at very low shear rates and, therefore, support the existence of a directional order parameter.

Morphology determination of defect-rich diblock copolymer films with time-of-flight grazing-incidence small-angle neutron scattering

2014 ◽  
Vol 47 (4) ◽  
pp. 1228-1237 ◽  
Author(s):  
Peter Müller-Buschbaum ◽  
Gunar Kaune ◽  
Martin Haese-Seiller ◽  
Jean-Francois Moulin
Keyword(s):  
Neutron Scattering ◽  
Diblock Copolymer ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Microphase Separation ◽  
Time Of Flight ◽  
Surface Region ◽  
Grazing Incidence ◽  
Near Surface ◽  
Oriented Parallel

The complex nanomorphology of a defect-rich deuterated poly(styrene-block-methyl methacrylate), P(S-b-MMAd), diblock copolymer film is determined with a combination of grazing-incidence small-angle neutron scattering (GISANS) and time-of-flight (TOF) mode. TOF-GISANS enables the simultaneous performance of several GISANS measurements that differ in wavelength. The resulting set of GISANS data covers different ranges of the scattering vector and has different scattering depths. Thus surface-sensitive and bulk-sensitive measurements can be performed simultaneously. The P(S-b-MMAd) film exhibits a lamellar microphase separation structure, which because of the defects is arranged into small, randomly oriented grains, composed of four–five lamellar repetitions. In the near-surface region, the lamellar structure is oriented parallel to the substrate, which explains the smooth surface found with atomic force microscopy.

scholarly journals Custom AFM for X-ray beamlines:in situbiological investigations under physiological conditions

2015 ◽  
Vol 22 (6) ◽  
pp. 1364-1371 ◽  
Author(s):  
B. Gumí-Audenis ◽  
F. Carlà ◽  
M. V. Vitorino ◽  
A. Panzarella ◽  
L. Porcar ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Structural Information ◽  
Grazing Incidence ◽  
X Rays ◽  
Liquid Environment ◽  
X Ray ◽  
Physiological Conditions ◽  
Atomic Force ◽  
Wide Range ◽  
Solid Liquid

A fast atomic force microscope (AFM) has been developed that can be installed as a sample holder for grazing-incidence X-ray experiments at solid/gas or solid/liquid interfaces. It allows a wide range of possible investigations, including soft and biological samples under physiological conditions (hydrated specimens). The structural information obtained using the X-rays is combined with the data gathered with the AFM (morphology and mechanical properties), providing a unique characterization of the specimen and its dynamicsin situduring an experiment. In this work, lipid monolayers and bilayers in air or liquid environment have been investigated by means of AFM, both with imaging and force spectroscopy, and X-ray reflectivity. In addition, this combination allows the radiation damage induced by the beam on the sample to be studied, as has been observed on DOPC and DPPC supported lipid bilayers under physiological conditions.

scholarly journals Π-GISANS: probing lateral structures with a fan shaped beam

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alexei Vorobiev ◽  
Nicolò Paracini ◽  
Marité Cárdenas ◽  
Max Wolff
Keyword(s):  
Silicon Substrate ◽  
Free Water ◽  
Incident Beam ◽  
Depth Resolution ◽  
Grazing Incidence ◽  
One Dimension ◽  
Angle Scattering ◽  
Lateral Structures ◽  
Limited Depth ◽  
Neutron Small Angle Scattering

AbstractWe have performed grazing incidence neutron small angle scattering using a fan shaped incident beam focused along one dimension. This allows significantly reduced counting times for measurements of lateral correlations parallel to an interface or in a thin film where limited depth resolution is required. We resolve the structure factor of iron inclusions in aluminium oxide and show that the ordering of silica particles deposited on a silicon substrate depends on their size. We report hexagonal packing for 50 nm but not for 200 nm silica spheres deposited by a modified Langmuir-Schaefer method on a silicon substrate. For the 200 nm particles we extract the particles shape from the form factor. Moreover, we report dense packing of the particles spread on a free water surface. We name this method π-GISANS to highlight that it differs from GISANS as it gives lateral information while averaging the in-depth structure.

Bifocal miniature toroidal shaped X-ray mirrors

2010 ◽  
Vol 25 (2) ◽  
pp. 154-156
Author(s):  
Sterling Cornaby ◽  
Detlef-M. Smilgies ◽  
Donald H. Bilderback
Keyword(s):  
Angular Resolution ◽  
Grazing Incidence ◽  
Horizontal Direction ◽  
Wide Angle ◽  
X Ray ◽  
Angle Scattering ◽  
Wide Range

We have fabricated a bifocal miniature toroidal mirror that horizontally and vertically focuses to two different locations to provide a smaller footprint of the beam for grazing-incidence wide-angle scattering (GIWAXS), while at the same time focusing the beam in the horizontal direction on the detector to further enhance the angular resolution. At CHESS we traditionally use glass single-bounce monocapillary optics for a wide range of X-ray experiments to get a fine X-ray beam of 5 to 20 μm. This miniature toroidal mirror was prepared by designing and fabricating an X-ray focusing capillary in which the sagittal and meridional focusing is decoupled and only a quadrant of the accepted annulus is used for focusing the beam. The mirror produced a 120 μm horizontal by 25 μm vertical focus at 50 mm from the tip of the optic and a 44 μm horizontal by 70 μm vertical focus at 150 mm from the tip of the optic.

Soil Chemical Pollution and Aggressive Pathologies

2018 ◽  
Vol 69 (8) ◽  
pp. 2278-2282
Author(s):  
Stelian Ioan Morariu ◽  
Letitia Doina Duceac ◽  
Alina Costina Luca ◽  
Florina Popescu ◽  
Liliana Pavel ◽  
...  
Keyword(s):  
Health Care Professionals ◽  
Scientific Progress ◽  
Volcanic Eruptions ◽  
Chemical Pollution ◽  
Optimal Parameters ◽  
Chemical Pollutants ◽  
Wide Range ◽  
Health Physician ◽  
Solid Liquid

Maintaining the soil in optimal parameters is vital for mankind, given its essential role in providing the alimentary base, as well as its extremely slow formation and regeneration (hundreds or thousands of years). The direct and indirect pollution of the soil and especially its chemical pollution represent a corollary of other types of pollution, given that it is produced by solid, liquid and gaseous residues. It may be involved in a wide range of diseases (respiratory, cardiovascular, digestive, renal, haematological, osteoarticular, neurological) of allergic, infectious, degenerative or neoplastic nature, from infancy to the old age. Although there are natural causes of soil pollution (e.g. volcanic eruptions), most pollutants come from human activities, which are the most incriminated in its pollution, degradation and erosion at an accelerated pace. The growing concern of all nations for the adoption of measures to limit the chemical pollution of the soil is partially found so far in viable and effective solutions intended to combat soil contamination and degradation and ensure its restoration. Chemical industrialization leads to technical and scientific progress, but at the same time it can develop related pathologies, which means that the role of the occupational health physician is essential in ensuring prophylaxis and the early detection of occupational diseases. Besides that, the role of the pediatrician is equally precious for the detection of specific diseases caused by chemical pollutants to children, because they will develop into adults with pathological stigma.The chemical pollution of the soil is a major challenge for ecologists, given that it is an important risk factor for many types of afflictions. It requires maximum attention from civil society, health care professionals and government institutions. The specialist in occupational medicine, as well as the pediatrician bear an essential responsibility in both, prevention and treatment.

Wetting of glass surface using natural surfactants

2020 ◽  
Vol 12 ◽  
Author(s):  
Nihar Ranjan Biswal
Keyword(s):  
Contact Angle ◽  
Glass Surface ◽  
Pure Water ◽  
Amyl Alcohol ◽  
Synthetic Surfactant ◽  
Wide Range ◽  
Different Types ◽  
Natural Surfactants ◽  
Triton X ◽  
Solid Liquid

Background: Surfactant adsorption at the interfaces (solid–liquid, liquid–air, or liquid–liquid) is receiving considerable attention from a long time due to its wide range of practical applications. Objective: Specifically wettability of solid surface by liquids is mainly measured by contact angle and has many practical importances where solid–liquid systems are used. Adsorption of surfactants plays an important role in the wetting process. The wetting behaviours of three plant-based natural surfactants (Reetha, Shikakai, and Acacia) on the glass surface are compared with one widely used nonionic synthetic surfactant (Triton X-100) and reported in this study. Methods: The dynamic contact angle study of three different types of plant surfactants (Reetha, Shikakai and Acacia) and one synthetic surfactant (Triton X 100) on the glass surface has been carried out. The effect of two different types of alcohols such as Methanol and amyl alcohol on wettability of shikakai, as it shows little higher value of contact angle on glass surface has been measured. Results: The contact angle measurements show that there is an increase in contact angle from 47° (pure water) to 67.72°, 65.57°, 68.84°, and 68.79° for Reetha, Acacia, Shikakai, and Triton X-100 respectively with the increase in surfactant concentration and remain constant at CMC. The change in contact angle of Shikakai-Amyl alcohol mixtures are slightly different than that of methanol-Shikakai mixture, mostly there is a gradual increase in contact angle with the increasing in alcohol concentration. Conclusion: There is no linear relationship between cos θ and inverse of surface tension. There was a linear increase in surface free energy results with increase in concentration as more surfactant molecules were adsorbing at the interface enhancing an increase in contact angle.

scholarly journals Numerical Phase-Field Model Validation for Dissolution of Minerals

2021 ◽  
Vol 11 (6) ◽  
pp. 2464
Author(s):  
Sha Yang ◽  
Neven Ukrainczyk ◽  
Antonio Caggiano ◽  
Eddie Koenders
Keyword(s):  
Phase Field ◽  
Liquid Interface ◽  
Mineral Dissolution ◽  
Experimental Results ◽  
Wide Range ◽  
Congruent Dissolution ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Dissolution Of Minerals ◽  
Meso Scale

Modelling of a mineral dissolution front propagation is of interest in a wide range of scientific and engineering fields. The dissolution of minerals often involves complex physico-chemical processes at the solid–liquid interface (at nano-scale), which at the micro-to-meso-scale can be simplified to the problem of continuously moving boundaries. In this work, we studied the diffusion-controlled congruent dissolution of minerals from a meso-scale phase transition perspective. The dynamic evolution of the solid–liquid interface, during the dissolution process, is numerically simulated by employing the Finite Element Method (FEM) and using the phase–field (PF) approach, the latter implemented in the open-source Multiphysics Object Oriented Simulation Environment (MOOSE). The parameterization of the PF numerical approach is discussed in detail and validated against the experimental results for a congruent dissolution case of NaCl (taken from literature) as well as on analytical models for simple geometries. In addition, the effect of the shape of a dissolving mineral particle was analysed, thus demonstrating that the PF approach is suitable for simulating the mesoscopic morphological evolution of arbitrary geometries. Finally, the comparison of the PF method with experimental results demonstrated the importance of the dissolution rate mechanisms, which can be controlled by the interface reaction rate or by the diffusive transport mechanism.

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