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The use of X‐ray and neutron reflectivity has been generalized worldwide for scientists who want to determine specific physical properties (such as electron‐density profile, scattering‐length density, roughness and thickness) of films less than 200 nm thick deposited on a substrate. This paper describes a freeware program named REFLEX, which is a standalone program dedicated to the simulation and analysis of X‐ray and neutron reflectivity from multilayers. This program was first written two decades ago and has been constantly improved since, but never published until now. The latest version of REFLEX covers generalized types of calculation of reflectivity curves including both neutron and X‐ray reflectivity. In the case of X‐rays, the program can deal with both s and p polarization, which is quite important in the soft X‐ray region where the two polarizations can yield different results. Neutron reflectivity is calculated within the framework of non‐spin‐polarized neutrons. REFLEX has also been designed to include any type of fluid (such as supercritical CO2) on top of the analysed film and includes corrections of the footprint effect for analysis on an absolute scale. REFLEX is a user‐friendly program dedicated to the analysis of specular X‐ray (soft and hard) and neutron reflectivity measurements. [ABSTRACT FROM AUTHOR]

Steady-state and dynamic swelling characteristics of PEO-PPO-PEO copolymer ultrathin films comprising 2-layered structure, where the bottom layer (L1) is made of one PEO (hydrophilic)-PPO (hydrophobic) bilayer and the top layer (L2) is made of two alternating PEO-PPO bilayers, have been studied at room temperature in precisely controlled environment of 10-93% relative humidity (RH). Swelling, which is monitored by measuring the thickness of the films using X-ray reflectivity (XRR), is found to be largely dissimilar in differently thick films prepared by varying the concentration of mother solutions from 1 g/L to 4 g/L. This is well explained considering a preferential-swelling of amphiphilic block copolymer, where only the hydrophilic PEO blocks contribute in swelling and PPO acts a barrier in the diffusion of water molecules. The swelling kinetics is governed by the thickness/width and coverage of outer PPO block layer. [ABSTRACT FROM AUTHOR]

Focuses on the self-assembly of surfactant templated thin-film silica mesophases. Use of the cetyltrimethylammonium bromide as the structure-directing surfactant; Acidic conditions in which the siloxane condensation rate is minimized.

X-ray reflectivity experiments have been used to monitor the capillary condensation of water in mesoporous silica thin films. We show that both the Bragg peak intensities and the film critical wave vector transfer are very sensitive to water intrusion or extrusion from the pores. Similarly to what is achieved during adsorption and desorption of gas, adsorption isotherms can be measured by monitoring the evolution of the average electron density of the film as a function of the relative humidity. The pore size distribution of mesoporous silica thin films is further determined from the isotherms. [ABSTRACT FROM AUTHOR]

Two-dimensional hexagonal silica thin films templated by a triblock copolymer were investigated by grazing incident small angle x-ray scattering (GISAXS) and x-ray reflectivity (XR) before and after removing the surfactant from the silica matrix. XR curves—analyzed above and below the critical angle of the substrate—are evaluated by the matrix technique to obtain the average electron density of the films, the wall thickness, the electron density of the walls, the radius of the pores, and subsequently the porosity of such mesoporous films. In combination with GISAXS, the surface area of the mesopores is ascertained, thereby providing a complete analysis of the porosity in thin films by x-ray scattering methods. [ABSTRACT FROM AUTHOR]

Highlights • Copper nanopowder catalyst made removal of residual copper easy after click reaction. • Improved synthetic method also help scale up the synthesis of copper-free MH-b-PS. • The microphase separation of MH-b-PS was investigated by AFM, SAXS and GISAXS. • The phase of MH-b-PS transited from Hex to Bcc when changing the annealing solvent. Abstract The promising carbohydrate-based block copolymer maltoheptaose-block-polystyrene (MH-b-PS) has been used for high-performance memory transistors and next generation nanolithography. In order to realize the potential of MH-b-PS especially in microelectronic applications, we firstly improved its synthetic method for obtaining large amount of copper-free MH-b-PS. The main improvement relies on the removal of the residual copper catalyst by using a chelating resin. Then, the microphase separation of copper-free MH-b-PS in both thin film and bulk states under different solvent vapor annealing conditions were investigated comprehensively and compared with our previous report by using both real-space and reciprocal-space techniques. A phase transition of MH-b-PS from hexagonal close-packed horizontal cylinders to face-centered cubic were observed when increasing the amount of tetrahydrofuran in the mixture annealing solvent of tetrahydrofuran and H 2 O. More details about self-assembled MH-b-PS nanostructures were analyzed by comparing grazing incidence small angle X-ray scattering patterns with corresponding atomic force microscopy phase images. [ABSTRACT FROM AUTHOR]

The influence of the sample preparation on the observed dependence of glass transition temperature ( T g ) with thickness in polystyrene (PS) thin films has been investigated. Spectroscopic ellipsometry was used to measure the T g of PS thin films ranging from 7 to 85 nm before and after exposition to supercritical carbon dioxide (sc-CO 2 ). We take advantage of the sc-CO 2 properties along with thermal annealing treatment to cancel out sample preparation history factor by removing the remnant solvent and residual stresses. The decrease in T g shows exactly the same trend before and after sc-CO 2 exposure plus thermal treatment. This result cancels out the influence of the spin coating process on the T g depression in thin films. [ABSTRACT FROM AUTHOR]

• Optical and structural properties of pure and W doped VO 2 are reported at 25°C and 85°C. • Point-by-point method provides a robust determination of the optical properties. • Correlation between refractive index and thickness of V1-xWxO2 films are eliminated. • Transition temperature is lowered by increasing the concentration of W doping. • Coexistence of monoclinic and rutile structures in V1-xWxO2 for x = 3% at 25°C. Vanadium dioxide is one of the most promising materials that can be used to control and tune in real time the optical properties of nanoscale devices due to its ability to perform a Metal-Insulator Transition (MIT). In this paper, we report the optical and structural properties of undoped and W-doped V 1-x W x O 2 vanadium dioxide thin films deposited on oxidized silicon substrates using magnetron sputtering. The structural properties determined by X-ray diffraction showed not only the transition from a monoclinic to a rutile phase when crossing the metal–insulator transition temperature (T M I T) but also a coexistence of phases for the tungsten-doped VO 2 even at room temperature. It is also shown that T M I T decreases from 69.6°C to 41.6°C as x increases from 0 to 3%. A point-by-point fitting method is proposed to reliably extract the refractive index and extinction coefficient from spectroscopic ellipsometry measurements as a function of temperature and tungsten concentration. This approach avoids all the correlations between the thickness and the refractive index well known in absorbent films calling into question the uniqueness of the results. The dielectric function is then calculated from the point by point refractive index. A model based on Tauc-Lorentz oscillators in the insulating phase to which a Drude component is added in the metallic phase provides information on the levels of the energy bands and the plasma frequency of the films. The calculation of reflectance and transmittance of V 1-x W x O 2 thin films highlights the effect of W doping on thermochromic performance. [ABSTRACT FROM AUTHOR]