Search results for "Surfaces"
showing 10 items of 2837 documents
Structural reorganisation in polytopic receptors revealed by kinetic studies.
2010
One of the first kinetic studies of metal ion reorganisation between the different sites of a tritopic polyaza ligand reveals well defined pathways for the movement of the metal ion.
Surfactant self-assembly in the gas phase: Bis(2-ethylhexyl)sulfosuccinate- alkaline metal ion aggregates
2008
Molecular dynamics (MD) simulations were conducted for systems in vacuo consisting of n AOT anions (bis(2-ethylhexyl)sulfosuccinate ions) and n 1 or n Na+ ions up to n = 20. For n = 15, positively charged systems with Li+, K+, and Cs+ cations were also considered. All systems were observed to form reverse micelle-like aggregates whose centre is occupied by cations and polar heads in a very compact solid-like way, while globally the aggregate has the form of an elongated and rather flat ellipsoid. Various types of statistical analyses were carried out on the systems to enlighten structural and dynamical properties including gyration radius, atomic pair correlation functions, atomic B-factor …
Gas phase infrared multiple photon dissociation spectra of positively charged sodium bis(2-ethylhexyl)sulfosuccinate reverse micelle-like aggregates
2011
The capability of infrared multiple photon dissociation (IRMPD) spectroscopy to gain structural information on surfactant-based supramolecular aggregates has been exploited to elucidate intermolecular interactions and local organization of positively charged sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) aggregates in the gas phase. A detailed analysis of the stretching modes of the AOTNa CO and SO(3)(-) head groups allows one to directly probe their interactions with sodium counterions and to gain insight in their organization within the aggregate. Similarities and differences of the IRMPD spectra as compared to the infrared absorption spectrum of micellized AOTNa in CCl(4) have been analy…
Magnetic Langmuir-Blodgett films of ferritin with different iron contents.
2006
Magnetic Langmuir-Blodgett films of four ferritin derivatives with different iron contents containing 4220, 3062, 2200, and 1200 iron atoms, respectively, have been prepared by using the adsorption properties of a 6/1 mixed monolayer of methyl stearate (SME) and dioctadecyldimethylammonium bromide (DODA). The molecular organization of the mixed SME/DODA monolayer is strongly affected by the presence of the water-soluble protein in the subphase as shown by pi-A isotherms, BAM images, and imaging ellipsometry at the water-air interface. BAM images reveal the heterogeneity of this mixed monolayer at the air-water interface. We propose that the ferritin is located under the mixed matrix in thos…
A noise analyzer for monitoring static electrification current
2005
Abstract This paper presents a static electrification current signal analyzer used for measuring and processing of the variable component of the changes in electrostatic charge that occur on a solid-body/liquid boundary interface. Due to high sensitivity and low uncertainty, the analyzer allows a precise evaluation of the phenomenon generated. The device operates in a spinning-disk system. The tests carried out indicate that it is possible to measure random components which depend, to a large extent, on hydrodynamic conditions and on the properties of the liquid phase. The device can be applied to the testing of transformer oils. It can be also used for measurements of other liquids having …
Design of a real-time spectroscopic rotating compensator ellipsometer without systematic errors
2014
6th International Conference on Spectroscopic Ellipsometry (ICSE), Kyoto, JAPAN, MAY 26-31, 2013; International audience; We describe a spectroscopic ellipsometer in the visible domain (400-800 nm) based on a rotating compensator technology using two detectors. The classical analyzer is replaced by a fixed Rochon birefringent beamsplitter which splits the incidence light wave into two perpendicularly polarized waves, one oriented at +45 degrees and the other one at-45 degrees according to the plane of incidence. Both emergent optical signals are analyzed by two identical CCD detectors which are synchronized by an optical encoder fixed on the shaft of the step-by-step motor of the compensato…
Supra-aggregates of fiber-forming anisotropic molecules.
2006
In this paper, the self-organization of fiber-forming anisotropic molecules is inspected both theoretically and experimentally. In the first part, a theoretical model which extends the de Gennes theory of thin films to assemblies of strongly anisotropic molecules is reported. The model predicts that solid supported thin films made up of fiber-forming discotic molecules can grow with both tangential and radial arrangement of the fibers, respectively leading to the formation of compact and holed supra- aggregates. These last systems form according to the following picture. The tangential growth minimizes the number of unfavorable free ends but introduces elastic strain especially in the centr…
Spin relaxation in Cu and Al spin conduits
2014
We study the spin relaxation in Al and Cu spin conduits embedded in non-local spin valve nanostructures. Measuring the key spin transport properties, we determine the spin and charge diffusion constants as well as the spin flip time. By varying the temperature, we find that the maximum of the non-local spin resistance change occurs at finite temperatures with a clear difference between Al and Cu. In particular, we find that the maximum of the non-local spin signal in Al is less pronounced and occurs at lower temperatures compared to Cu suggesting that the self-passivating Al surface plays a role. Having fabricated devices with both materials in identical processes, we can attribute the diff…
Element-specific ferromagnetic resonance in epitaxial Heusler spin valve systems
2011
Time-resolved x-ray magnetic circular dichroism was used to investigate epitaxial MgO(100)/Co2Cr0.6Fe0.4Al and MgO(100)/Co2Cr0.6Fe0.4Al/Cr/CoFe films. The precessional motion of the individual sublattice magnetization, excited by continuous microwave excitation in the range 2–10 GHz, was detected by tuning the x-ray photon energy to the L 3 absorption edges of Cr, Fe and Co. The relative phase angle of the sublattice magnetization's response is smaller than the detection limit of 2°. A weakly antiferromagnetically coupled CoFe layer causes an increase in the ferromagnetic resonance linewidth consisting of a constant offset and a component linearly increasing with frequency that we partly at…
Pressure-Induced High Spin State in [Fe(btr)2(NCS)2]·H2O (btr = 4,4′-bis-1,2,4-triazole)
2000
Application of hydrostatic pressure (≤ 10.5 kbar) on the two-dimensional spin transition compound [Fe(btr)2(NCS)2]·H2O (btr = 4,4‘-bis-1,2,4-triazole) results in an unexpected stabilization of the HS state. On release of the pressure, the HS state is found to be partially trapped. After thermal relaxation of the metastable HS state obtained by the LIESST effect (light-induced excited spin state trapping), a pure LS state is obtained in contrast to the pressure experiments. This different behavior supports a structural phase transition as the likely basis of the pressure-induced HS state.