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In situ grazing-incidence small-angle X-ray scattering observation of block-copolymer templated formation of magnetic nanodot arrays and their magnetic properties

The fabrication of bit-patterned media (BPM) is crucial for new types of hard disk drives. The development of methods for the production of BPM is progressing rapidly. Conventional lithography reaches the limit regarding lateral resolution, and new routes are needed. In this study, we mainly focus on the dependence of the size and shape of magnetic nanodots on the Ar+-ion etching duration, using s

Structural observation of piezoelectric inhomogeneity in a mixed-orientation Na0.5Bi0.5TiO3 perovskite thin film

Thin films of the lead-free ferroelectric Na0.5Bi0.5TiO3 grown on thin-film Pt electrodes supported by SrTiO3 substrates have a complex microstructure consisting of crystalline grains with three distinct major crystallographic orientations. The piezoelectric response measured in spatially separated sub-micron grains using time-resolved synchrotron x-ray microdiffraction is highly inhomogeneous eve

Deep Brain Stimulation in the Subthalamic Nuclei Alters Postural Alignment and Adaptation in Parkinson’s Disease

Parkinson’s disease (PD) can produce postural abnormalities of the standing body position such as kyphosis. We investigated the effects of PD, deep brain stimulation (DBS) in the subthalamic nucleus (STN), vision and adaptation on body position in a well-defined group of patients with PD in quiet standing and during balance perturbations. Ten patients with PD and 25 young and 17 old control partic

Nanostructure of biogenic calcite and its modification under annealing : Study by high-resolution X-ray diffraction and nanoindentation

We apply advanced X-ray diffraction techniques at synchrotron microfocus beamlines in order to study the local ultrastructure of biogenic calcite with high spatial and angular resolution. Specifically, we investigate individual calcitic prisms extracted from Pinna nobilis mollusk shells with an aim to shed additional light on the structural aspects of organic/inorganic interfaces. We use annealing

Scanning X-ray strain microscopy of inhomogeneously strained Ge micro-bridges

Strained semiconductors are ubiquitous in microelectronics and microelectromechanical systems, where high local stress levels can either be detrimental for their integrity or enhance their performance. Consequently, local probes for elastic strain are essential in analyzing such devices. Here, a scanning X-ray sub-microprobe experiment for the direct measurement of deformation over large areas in

Time-dependent relaxation of strained silicon-on-insulator lines using a partially coherent x-ray nanobeam

We report on the quantitative determination of the strain map in a strained silicon-on-insulator line with a 200×70 nm2 cross section. In order to study a single line as a function of time, we used an x-ray nanobeam with relaxed coherence properties as a compromise between beam size, coherence, and intensity. We demonstrate how it is possible to refine the line deformation map at the nanoscale, an

Correlation of electrical and structural properties of single as-grown GaAs nanowires on Si (111) substrates

We present the results of the study of the correlation between the electrical and structural properties of individual GaAs nanowires measured in their as-grown geometry. The resistance and the effective charge carrier mobility were extracted for several nanowires, and subsequently, the same nano-objects were investigated using X-ray nanodiffraction. This revealed a number of perfectly stacked zinc

Diverse ultrastructural landscape of atherosclerotic endothelium

Background and aims: The endothelium plays a major role in atherosclerosis, yet the endothelial plaque surface is a largely uncharted territory. Here we hypothesize that atherosclerosis-driven remodeling of the endothelium is a dynamic process, involving both damaging and regenerative mechanisms. Methods: Using scanning electron microscopy (SEM) and immuno-SEM, we studied endothelial junction ultr

Imaging of strain and lattice orientation by quick scanning X-ray microscopy combined with three-dimensional reciprocal space mapping

Numerous imaging methods have been developed over recent years in order to study materials at the nanoscale. Within this context, scanning X-ray diffraction microscopy has become a routine technique, giving access to structural properties with sub-micrometre resolution. This article presents an optimized technique and an associated software package which have been implemented at the ID01 beamline

Distribution of zinc-blende twins and wurtzite segments in GaAs nanowires probed by X-ray nanodiffraction

We study by X-ray nanodiffraction the statistical distribution of the two possible twinned zinc-blende (ZB) orientations as well as the occurrence of the wurtzite structure within single GaAs nanowires (NWs) grown by molecular beam epitaxy on Si(111). A fast scanning scheme allowed to perform diffraction experiments on 160 individual NWs. We find that although on average the two ZB orientations sh

Counting dislocations in microcrystals by coherent X-Ray diffraction

We present here an unprecedented way of quantifying the number of dislocations in microcrystals. This method relies on a combination of several state-of-the-art techniques: coherent x-ray diffraction used as a local probe, together with the controlled compression of micro-objects. We demonstrate that by using this method, dislocations in the microcrystal can be detected and their number precisely

Ageing dynamics of ion bombardment induced self-organization processes

Instabilities caused during the erosion of a surface by an ion beam can lead to the formation of self-organized patterns of nanostructures. Understanding the self-organization process requires not only the in-situ characterization of ensemble averaged properties but also probing the dynamics. This can be done with the use of coherent X-rays and analyzing the temporal correlations of the scattered

X-ray scattering studies of nanodot pattern formation on semiconductor surfaces by low energy ion beam sputtering

We show the capability of in-situ and ex-situ grazing-incidence small angle X-ray scattering (GISAXS) and diffraction (GID) techniques, using synchrotron radiation, to study the formation of self-organized nanodot patterns on semiconductor targets by ion beam sputtering (IBS). Particularly, surface nanopatterns of short-range hexagonal arrays of nanodots (as observed by atomic force microscopy ima

Ion beam sputtered surface dynamics investigated with two-time correlation functions : A model study

Ion beam sputtering is a widely used technique to obtain patterned surfaces. Despite the wide use of this approach on different materials to create surface nanostructures, the theoretical model to explain the time evolution of the erosion process is still debated. We show, with the help of simulations, that two-time correlation functions can serve to assess the validity of different models. These

Coherent x-ray wavefront reconstruction of a partially illuminated Fresnel zone plate

A detailed characterization of the coherent x-ray wavefront produced by a partially illuminated Fresnel zone plate is presented. We show, by numerical and experimental approaches, how the beam size and the focal depth are strongly influenced by the illumination conditions, while the phase of the focal spot remains constant. These results confirm that the partial illumination can be used for cohere

Organ specific copy number variations in visceral metastases of human melanoma

Malignant melanoma is one of the most aggressive skin cancers with high potential of visceral dissemination. Since the information about melanoma genomics is mainly based on primary tumors and lymphatic or skin metastases, an autopsy-based visceral metastasis biobank was established. We used copy number variation arrays (N = 38 samples) to reveal organ specific alterations. Results were partly com

X-ray nanodiffraction on a single SiGe quantum dot inside a functioning field-effect transistor

For advanced electronic, optoelectronic, or mechanical nanoscale devices a detailed understanding of their structural properties and in particular the strain state within their active region is of utmost importance. We demonstrate that X-ray nanodiffraction represents an excellent tool to investigate the internal structure of such devices in a nondestructive way by using a focused synchotron X-ray

Three-dimensional diffraction mapping by tuning the X-ray energy

Three-dimensional reciprocal-space maps of a single SiGe island around the Si(004) Bragg peak are recorded using an energy-tuning technique with a microfocused X-ray beam with compound refractive lenses as focusing optics. The map is in agreement with simulated data as well as with a map recorded by an ordinary rocking-curve scan. The energy-tuning approach circumvents both the comparatively large

Imaging the displacement field within epitaxial nanostructures by coherent diffraction : A feasibility study

We investigate the feasibility of applying coherent diffraction imaging to highly strained epitaxial nanocrystals using finite-element simulations of SiGe islands as input in standard phase retrieval algorithms. We discuss the specific problems arising from both epitaxial and highly strained systems and we propose different methods to overcome these difficulties. Finally, we describe a coherent mi