Nonionic Fluorinated Surfactant Removal from Mesoporous Film Using sc-CO.

Surfactant templated silica thin films were self-assembled on solid substrates by dip-coating using a partially fluorinated surfactant R(EO) as the liquid crystal template. The aim was 2-fold: first we checked which composition in the phase diagram was corresponding to a 2D rectangular highly ordered crystalline phase and second we exposed the films to sc-CO to foster the removal of the surfactant. The films were characterized by in situ X-ray reflectivity (XRR) and grazing incidence small angle X-ray scattering (GISAXS) under CO pressure from 0 to 100 bar at 34 °C.

From permeation to pore nucleation in smectic stacks.

The last stage of the spreading of a stratified droplet in the odd wetting case is the evolution from a trilayer to a monolayer, that is, vanishing of the last bilayer in the stack. We studied it in the case of 8CB smectic liquid crystal on a hydrophilic surface. Receding of the last bilayer is accompanied by formation of pores in it, which appear in the outer part of it.

Sliding velocity dependence of adhesion in a nanometer-sized contact.

The influence of sliding velocity on the adhesion force in a nanometer-sized contact was investigated with a novel atomic force microscope experimental setup that allows measuring adhesion forces while the probe is sliding at continuous and constant velocities. For hydrophobic surfaces, the adhesion forces (mainly van der Waals forces) remain constant, whereas for hydrophilic surfaces, adhesion forces (mainly capillary forces) decrease linearly with a logarithmic increase of the sliding velocity. The experimental data are well explained by a model based on a thermally activated growth process of a capillary meniscus.

Nanoscale noncontact subsurface investigations of mechanical and optical properties of nanoporous low-k material thin film.

Revealing defects and inhomogeneities of physical and chemical properties beneath a surface or an interface with in-depth nanometric resolution plays a pivotal role for a high degree of reliability in nanomanufacturing processes and in materials science more generally. (1, 2) Nanoscale noncontact depth profiling of mechanical and optical properties of transparent sub-micrometric low-k material film exhibiting inhomogeneities is here achieved by picosecond acoustics interferometry. On the basis of the optical detection through the time-resolved Brillouin scattering of the propagation of a picosecond acoustic pulse, depth profiles of acoustical velocity and optical refractive index are measured simultaneously with spatial resolution of tens of nanometers.

Circular mode: a new scanning probe microscopy method for investigating surface properties at constant and continuous scanning velocities.

In this paper, we introduce a novel scanning probe microscopy mode, called the circular mode, which offers expanded capabilities for surface investigations especially for measuring physical properties that require high scanning velocities and/or continuous displacement with no rest periods. To achieve these specific conditions, we have implemented a circular horizontal displacement of the probe relative to the sample plane. Thus the relative probe displacement follows a circular path rather than the conventional back and forth linear one.

Laser ultrasonics detection of an embedded crack in a composite spherical particle.

Laser ultrasonics was applied to the manufacturing control of the integrity (no failure) of coated spherical particles designed for High Temperature Reactors (HTR). This control is of major importance, since the coating of the nuclear fuel kernel is designed to prevent from the diffusion of fission products outside the particle during reactor operation. The SiC layer composing the coating is particularly important, since this layer must be an impenetrable barrier for fission products.

Surface characterization and efficiency of a matrix-free and flat carboxylated gold sensor chip for surface plasmon resonance (SPR).

We report the preparation and characterization of a matrix-free carboxylated surface plasmon resonance (SPR) sensor chip with high sensing efficiency by functionalizing a bare gold thin film with a self-assembled monolayer of 16-mercaptohexadecanoic acid (SAM-MHDA chip). The self assembled monolayer surface coverage of the gold layer was carefully evaluated and the SAM was characterized by infrared reflection absorption spectroscopy, X-ray photoemission spectroscopy, atomic force microscopy, X-ray reflectivity-diffraction, and SPR experiments with bovine serum albumin. We compared the SPR signal obtained on this chip made of a dense monolayer of carboxylic acid groups with commercially available carboxylated sensor chips built on the same gold substrate, a matrix-free C1 chip, and a CM5 chip with a ~100 nm dextran hydrogel matrix (GE Healthcare).

Direct visualization of laser-driven focusing shock waves.

Direct real-time visualization and measurement of laser-driven shock generation, propagation, and 2D focusing in a sample are demonstrated. A substantial increase of the pressure at the convergence of the cylindrical acoustic shock front is observed experimentally and simulated numerically. Single-shot acquisitions using a streak camera reveal that at the convergence of the shock wave in water the supersonic speed reaches Mach 6, corresponding to the multiple gigapascal pressure range ∼30 GPa.

Late stage spreading of stratified liquids: theory.

Spreading of a liquid crystal droplet on a solid surface resembles the collapse of a zigguratlike structure and ends up with only two molecular terraces. A model is proposed to describe the time evolution of this late stage structure. It differs from the previous de Gennes-Cazabat theory by several aspects: (1) it avoids previous approximations and gives exact solutions of the kinetic equations; (2) it covers strongly layered liquids such as smectic liquid crystals; (3) it introduces the two-dimensional Laplace pressure as an essential motor for spreading; (4) it takes into account the liquid∕gas transition in the surface layer that was consistently reported in experiments with 8CB.

X-ray analysis of mesoporous silica thin films templated by Brij58 surfactant.

The structural optimization of highly mesoporous silica thin film templated with Brij58 is reported in this paper. The best conditions for obtaining well organized films are studied as a function of the concentration of surfactant, the relative humidity (RH) and the aging time of the solutions used in the dip-coating process. We first show on the basis of the results obtained by small angle x-ray scattering (SAXS) experiments on the binary system Brij58/water that the structure of the films determined by grazing incidence (GI) SAXS experiments can be explained according to a specific equation involving the initial masses of the sol constituents.

A simple method of surface functionalisation for immuno-specific immobilisation of proteins.

We present a new and advanced methodology, developed for surface functionalisation of gold and to study immobilisation of an immuno-specific system of proteins. A combination of electrochemical quartz crystal microbalance and Raman spectroscopy techniques allowed a complete understanding of the system starting from surface functionalisation and progressing to the functional structure analysis of immobilised proteins. A simple electrochemical procedure was formulated to prepare sulphonyl chloride terminated gold surfaces that form a strong sulphonamide bond with the receptor protein staphylococcal protein A (SpA).

Jones matrix formalism for the theory of picosecond shear acoustic pulse detection.

A theoretical analysis of the transient optical reflectivity of a sample by a normalized Jones matrix is presented. The off-diagonal components of the normalized matrix are identified with the complex rotation of the polarization ellipse. Transient optical polarimetry is a relevant technique to detect shear acoustic strain pulses propagating normally to the surface of an optically isotropic sample.

Study of titanium oxide sol-gel condensation using small angle X-ray scattering.

Transparent gels prepared from an acid solution of TiOCl(2) in N,N-dimethylformamide (DMF) and water have been studied by small-angle X-ray scattering (SAXS). The sol-gel transformation of the titanium inorganic polymer was studied as a function of chemical composition of the sol and of the annealing time. Quantitative information was obtained by modeling the SAXS data with the Burford and Beaucage models.

Reaction mechanisms of Li(0.30)La(0.57)TiO3 powder with ambient air: H+/Li+ exchange with water and Li2CO3 formation.

The proton/lithium exchange property of the lithium lanthanum titanate Li(0.30)La(0.57)TiO(3) (named LLTO) is shown to occur at room temperature under ambient air.

Multi-approach electron paramagnetic resonance investigations of UV-photoinduced Ti(3+) in titanium oxide-based gels.

EPR investigations of the photoreduction of Ti(4+) into Ti(3+) under UV irradiation were carried out on three titanium-based materials for which the initial concentration of Ti(4+) was defined in the ternary phase diagram (TiOCl(2), H(2)O, DMF). The kinetics of this photoreduction was monitored at 200 K and related to the initial concentration of Ti(4+) in the solution. This study was complemented by a multi-approach EPR method (pulsed electron paramagnetic resonance (EPR), pulsed electron nuclear double resonance, and hyperfine sublevel correlation spectroscopy (HYSCORE)) with the aim of probing the proton environment of the Ti(3+) ions.

TiO2 thin films self-assembled with a partly fluorinated surfactant template.

New TiO(2) films have been self-assembled on solid substrate by dip-coating using TiCl(4) as the titanium source and the partly fluorinated surfactant F(CF(2))(8)C(2)H(4)(OC(2)H(4))(9)OH as the liquid crystal template. By control over the dip-withdrawal speed, film thicknesses from a minimum of 43 nm were produced with rms roughnesses of 0.5-0.

Magnetic behaviour of nickel-cyclam complexes in mesoporous silica: EPR investigations.

Electron paramagnetic resonance (EPR) investigations are carried out on mesoporous silica (SBA15) functionalized by Ni-cyclam complexes (1,4,8,11-tetraazacyclotetradecane groups chelating nickel ions). The magnetic behaviour of nickel-cyclam groups, their mutual interactions and dispersions in the mesoporous silica are compared with respect to the doping rates and the synthesis procedures. The spin-spin interactions and the relaxation processes were clarified from the thermal evolution in the temperature range (4 K, 300 K) of the paramagnetic spin susceptibilities and EPR line widths.

How acoustic waves are guided in buried subsurface channels in unconsolidated granular media.

We show the existence of natural subsurface channels that guide acoustic waves for periodic arrays of spherical grains under the influence of gravity. Downward propagation of acoustic rays can be stopped altogether as a result of a caustic whose origin lies in the continuous bending of rays as a result of a gravitationally induced increase of rigidity with depth. Upward propagation of acoustic rays, on the other hand, is attenuated by Bragg reflection arising from the continuous diminishing of rigidity in the direction of the surface, resulting in a vertical propagation constant that approaches a limited allowed value.

Cheap and robust ultraflat gold surfaces suitable for high-resolution surface modification.

A simple procedure to elaborate robust ultraflat gold surface without clean room facilities is presented. Self-assembled 3-mercaptopropytriethoxysilane (MPTMS) on silicon was used as a buffer layer on which gold was sputtered using a common sputter-coating apparatus. The optimization of the sample position into the chamber of the sputtering machine yielded the formation of a thin (approximately 8 nm) gold layer.

Advances in structural analysis of fluoroaluminates using DFT calculations of 27Al electric field gradients.

Based on the analysis of 23 aluminum sites from 16 fluoroaluminates, the present work demonstrates the strong potential of combining accurate NMR quadrupolar parameter measurements, density functional theory (DFT)-based calculations of electric field gradients (EFG), and structure optimizations as implemented in the WIEN2k package for the structural and electronic characterizations of crystalline inorganic materials. Structure optimizations are essential for compounds whose structure was refined from usually less accurate powder diffraction data and provide a reliable assignment of the 27Al quadrupolar parameters to the aluminum sites in the studied compounds. The correlation between experimental and calculated EFG tensor elements leads to the proposition of a new value of the 27Al nuclear quadrupole moment Q(27Al) = 1.

Magnon coherent conductance via atomic nanocontacts.

A calculation for the coherent scattering and conductance of magnons via atomic nanocontacts is presented. The model system is composed of two groups of semi-infinite magnetically ordered Heisenberg monatomic chains, joined together by the magnetic nanocontact, and the system is supported on a non-magnetic substrate and considered otherwise free from magnetic interactions. The coherent transmission and reflection coefficients are derived as elements of a Landauer-type scattering matrix.

Real-time quantitative imaging of submolecular layers.

Using a recent optical contrast method, real-time and quantitative imaging of submolecular layers was performed with the help of a simple optical microscope. The measuring technique is exposed and documented by three examples. In particular, it allowed label-free detection of peptide-antibody binding interactions with 50 pg/mm2 sensitivity while keeping full optical lateral resolution.

Quantitative SAXS analysis of the P123/water/ethanol ternary phase diagram.

The ternary phase diagram of the amphiphilic triblock copolymer PEO-PPO-PEO ((EO)(20)(PO)(70)(EO)(20) commercialized under the generic name P123), water, and ethanol has been investigated at constant temperature (T = 23 degrees C) by small-angle X-ray scattering (SAXS). The microstructure resulting from the self-assembly of the PEO-PPO-PEO block copolymer varies from micelles in solution to various types of liquid crystalline phases such as cubic, 3D hexagonal close packed spheres (HCPS), 2D hexagonal, and lamellar when the concentration of the polymer is increased. In the isotropic liquid phase, the micellar structural parameters are obtained as a function of the water-ethanol ratio and block copolymer concentration by fitting the scattering data to a model involving core-shell form factor and a hard sphere structure factor of interaction.

Profiles of initially sinusoidal waves propagating in nonlinear microinhomogeneous materials.

The asymptotic analytical theory predicting acoustic wave profiles in microinhomogeneous materials with hysteretic quadratic nonlinearity and attenuation proportional to an even power of frequency is developed. The theory predicts that the influence on the nonlinear wave of the Rayleigh scattering of acoustic waves, which is proportional to the forth power of frequency, results in the net diminishing of wave attenuation. This is due to the suppression (diminishing) by scattering of the nonlinear hysteretic losses which is more important than direct increase in linear losses added by scattering.

NMR study of Li+ ion dynamics in the perovskite Li(3x)La(1/3-x)NbO3.

(7)Li and (6)Li nuclear magnetic resonance (NMR) experiments are carried out on the perovskite Li(3x)La(1/3-x)NbO(3). The results are compared to those obtained on the titanate Li(3x)La(2/3-x)TiO3 (LLTO) in order to investigate the effect, on the lithium ion dynamics, of the total substitution of Nb(5+) for Ti(4+) in the B-site of the ABO(3) perovskites. The XRD patterns analysis reveals that this substitution leads to a change in the distribution of the La(3+) ions in the structure.