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Together, the D8 range of diffraction solutions, and the DECTRIS PILATUS3 R 100K-A hybrid photon counting (HPC) pixel detector create an innovative 2D X-ray diffraction (XRD2) solution that is specifically suited for the characterization of multipurpose modern material research. This article discusses the features of this system, in a grazing incidence small angle X-ray scattering (GI-SAXS) mode for analyzing nanostructured surfaces.
The GI-SAXS technique is a combination of the surface sensitive nature of grazing incidence geometry, and a scattering range probing into the small angle region to obtain information about the nanoparticles and nanostructures in the surface layer. A 2D detector is used to collect the scattering as it enables access to the vertical and lateral nanostructures.
A nanostructured interface was created by applying 25 µl of 10 nm Au nanoparticles to a 5 x 15 mm area of a Si substrate surface. The next step was to allow the solution to dry to form a thin layer of nanoparticles. Figure 1 shows a D8 DISCOVER fitted with the IµS micro-focus source and PILATUS3 2D detector to measure the samples in reflection.
Figure 1. Instrumental setup used.
The PILATUS3 in 0D mode was employed to measure the optimal incidence angle, to obtain an X-ray reflectometry (XRR) scan. The XRR data shows that the angle is close to the critical angle. Each image was collected for 10 minutes, with a 500 µm primary beam collimator when the sample to detector distance was 33 cm. The deposition was continued with 25 µl increments until a total of 150 µl was applied (2 µl/mm2).
Figure 2 shows PILATUS3 images that were collected for nanoparticle concentrations of 0, 1, and 2 µl/mm2.
Figure 2. GISAXS result from PILATUS3 with various amounts of 10nm Au nanoparticles applied to a Si wafer. (a) 0µl/mm2 (b) 1µl/mm2 (c) 2µl/mm2.
The isotropic scattering shows that the nanoparticles configure in a three dimensional manner. There is an increase in nanoparticle concentration as expected, so higher order reflections can be seen. Conventionally, to block the specular reflection and transmitted primary beam, an elongated beam stop is employed. However, using the instant retrigger technology that provides a high dynamic range, the PILATUS3 removes the use of a beam stop.
Figure 3 shows a graph of intensity versus Qy generated by importing the data into DIFFRAC.LEPTOS, and integrating it along the horizon line. First order, second order and third order reflections from the 10 nm Au nanoparticles are witnessed close to the predicted positions of Q = 0.62 nm-1, Q = 1.26 nm-1 and Q = 1.89 nm-1 (Q=2nπ/d).
Figure 3. Qy integration of the data in Picture 2.
This information has been sourced, reviewed and adapted from materials provided by Bruker AXS Inc.
For more information on this source, please visit Bruker AXS Inc.