Implications of size dispersion on X-ray scattering of crystalline nanoparticles: CeO as a case study.

Controlling the shape and size dispersivity and crystallinity of nanoparticles (NPs) has been a challenge in identifying these parameters' role in the physical and chemical properties of NPs. The need for reliable quantitative tools for analyzing the dispersivity and crystallinity of NPs is a considerable problem in optimizing scalable synthesis routes capable of controlling NP properties. The most common tools are electron microscopy (EM) and X-ray scattering techniques.

Introduction to (): structural refinement of single crystals via X-ray phase measurements.

is a free Python package of computer codes for exploiting X-ray dynamic multiple diffraction in single crystals. A wide range of tools are available for evaluating the usefulness of the method, planning feasible experiments, extracting phase information from experimental data and further improving model structures of known materials. Graphical tools are also useful in analytical methodologies related to the three-dimensional aspect of multiple diffraction.

A simple formula for determining nanoparticle size distribution by combining small-angle X-ray scattering and diffraction results.

X-ray scattering and diffraction phenomena are widely used as analytical tools in nanoscience. Size discrepancies between the two phenomena are commonly observed in crystalline nanoparticle systems. The root of the problem is that each phenomenon is affected by size distribution differently, causing contrasting shifts between the two methods.

In-place bonded semiconductor membranes as compliant substrates for III-V compound devices.

Overcoming the critical thickness limit in pseudomorphic growth of lattice mismatched heterostructures is a fundamental challenge in heteroepitaxy. On-demand transfer of light-emitting structures to arbitrary host substrates is an important technological method for optoelectronic and photonic device implementation. The use of freestanding membranes as compliant substrates is a promising approach to address both issues.

X-ray dynamical diffraction in amino acid crystals: a step towards improving structural resolution of biological molecules physical phase measurements.

In this work, experimental and data analysis procedures were developed and applied for studying amino acid crystals by means of X-ray phase measurements. The results clearly demonstrated the sensitivity of invariant triplet phases to electronic charge distribution in d-alanine crystals, providing useful information for molecular dynamics studies of intermolecular forces. The feasibility of using phase measurements to investigate radiation damage mechanisms is also discussed on experimental and theoretical grounds.

Absolute refinement of crystal structures by X-ray phase measurements.

A pair of enantiomer crystals is used to demonstrate how X-ray phase measurements provide reliable information for absolute identification and improvement of atomic model structures. Reliable phase measurements are possible thanks to the existence of intervals of phase values that are clearly distinguishable beyond instrumental effects. Because of the high susceptibility of phase values to structural details, accurate model structures were necessary for succeeding with this demonstration.

Synchrotron X-ray imaging via ultra-small-angle scattering: principles of quantitative analysis and application in studying bone integration to synthetic grafting materials.

Optimized experimental conditions for extracting accurate information at subpixel length scales from analyzer-based X-ray imaging were obtained and applied to investigate bone regeneration by means of synthetic beta-TCP grafting materials in a rat calvaria model. The results showed a 30% growth in the particulate size due to bone ongrowth/ingrowth within the critical size defect over a 1-month healing period.

X-ray imaging in advanced studies of ophthalmic diseases.

Microscopic characterization of pathological tissues has one major intrinsic limitation, the small sampling areas with respect to the extension of the tissues. Mapping possible changes on vast tissues and correlating them with large ensembles of clinical cases is not a feasible procedure for studying most diseases, as for instance vision loss related diseases and, in particular, the cataract. Although intraocular lens implants are successful treatments, cataract still is a leading public-health issue that grows in importance as the population increases and life expectancy is extended worldwide.

Accurate triplet phase determination in non-perfect crystals--a general phasing procedure.

A completely different approach to the problem of physically measuring the invariant triplet phases by three-beam X-ray diffraction is proposed. Instead of simulating the three-beam diffraction process to reproduce the experimental intensity profiles, the proposed approach makes use of a general parametric equation for fitting the profiles and extracting the triplet phase values. The inherent flexibility of the parametric equation allows its applicability to be extended to non-perfect crystals.

An X-ray diffractometer for accurate structural invariant phase determination.

Instrumental advances and experimental procedures for determining invariant triplet phases by three-beam X-ray diffraction are presented. A simple X-ray diffractometer is described. It allows the exploitation of the natural linear polarization of synchrotron radiation for eliminating systematic errors in triplet-phase determination.

Enhanced x-ray phase determination by three-beam diffraction.

For decades, solving the phase problem of x-ray scattering has been a goal that, in principle, could be achieved by means of n-beam diffraction (n-BD). However, the phases extracted by the actual n-BD phasing techniques are not very precise, mainly due to systematic errors that are difficult to estimate. We present an innovative theoretical approach and experimental procedure that, combined, eliminate two major sources of error.