Grazing Incidence Small Angle X-ray Scattering Study Research Articles

Size, Shape, and Lateral Correlation of Highly Uniform, Mesoscopic, Self-Assembled Domains of Fluorocarbon-Hydrocarbon Diblocks at the Air/Water Interface: A GISAXS Study.

The shape and size of self-assembled mesoscopic surface domains of fluorocarbon-hydrocarbon (FnHm) diblocks and the lateral correlation between these domains were quantitatively determined from grazing incidence small-angle X-ray scattering (GISAXS). The full calculation of structure and form factors unravels the influence of fluorocarbon and hydrocarbon block lengths on the diameter and height of the domains, and provides the inter-domain correlation length. The diameter of the domains, as determined from the form factor analysis, exhibits a monotonic increase in response to the systematic lengthening of each block, which can be attributed to the increase in van der Waals attraction between molecules. The pair correlation function in real space calculated from the structure factor implies that the inter-domain correlation can reach a distance that is over 25 times larger than the domain's size. The full calculation of the GISAXS signals introduced here opens a potential towards the hierarchical design of mesoscale domains of self-assembled small organic molecules, covering several orders of magnitude in space.

GISAXS study on the size and distribution evolutions of Ag nanoparticles in ion-exchange glass during annealing

Silver-doped silicate composite glass had been synthesized with an ion-exchanged method. Grazing incidence small angle X-ray scattering (GISAXS) technique was used to investigate the size and distribution evolutions of Ag nanoparticles in the glass matrix in a subsequent thermal treatment process. GISAXS experiment reveals a change of size distribution of Ag nanoparticles from bimodal distribution to one-size distribution in annealing at 300 °C. The results demonstrate that the normalized volume fraction of smaller particles with average diameter of 6.4 nm almost no changed, but the bigger metastable ones dissolved gradually in an exponential decay way during the annealing process. It can be concluded that a multilayer nanostructure composed of silver nanoparticles was formed in the thermal process.

Structural characterization of supported nanocrystalline ZnO thin films prepared by dip-coating

Nanocrystalline ZnO thin films prepared by the sol–gel dip-coating technique were characterized by grazing incidence X-ray diffraction (GIXD), atomic force microscopy (AFM), X-ray reflectivity (XR) and grazing incidence small-angle X-ray scattering (GISAXS). The structures of several thin films subjected to (i) isochronous annealing at 350, 450 and 550°C, and (ii) isothermal annealing at 450°C during different time periods, were characterized. The studied thin films are composed of ZnO nanocrystals as revealed by analysing several GIXD patterns, from which their average sizes were determined. Thin film thickness and roughness were determined from quantitative analyses of AFM images and XR patterns. The analysis of XR patterns also yielded the average density of the studied films. Our GISAXS study indicates that the studied ZnO thin films contain nanopores with an ellipsoidal shape, and flattened along the direction normal to the substrate surface. The thin film annealed at the highest temperature, T=550°C, exhibits higher density and lower thickness and nanoporosity volume fraction, than those annealed at 350 and 450°C. These results indicate that thermal annealing at the highest temperature (550°C) induces a noticeable compaction effect on the structure of the studied thin films.

Morphology of encapsulated iron nanoparticles obtained by co-sputtering and implantation: a GISAXS study

A grazing incidence small-angle X-ray scattering (GISAXS) study is presented on the morphology of iron nanoparticles buried in carbon matrices, obtained either by ion-beam sputtering co-deposition or by ion-implantation. It is shown that, depending on the experimental synthesis conditions, the shape of the iron nanoparticles is either spherical or elongated perpendicularly to the substrate. The possible growth mechanisms are examined in terms of volume and surface diffusion, defect density, interfacial energy and residual stress.