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We report a hard x-ray patterning capable of drawing lines with a width below100 nm using x-rays at 0.165 nm. A specially prepared mask based on multilayer growth technology was used as an x-ray mask effectively. The x-ray Talbot effect in near field was investigated and utilized in the patterning. Since multilayers with a few nanometer layer spacing are readily available, the proposed hard x-ray nano patterning, free of the limit imposed by the Rayleigh criterion in optical range, can potentially be an ultimate optical lithography technique. [ABSTRACT FROM AUTHOR]

Back-reflection images obtained from single-crystal semiconductor substrates using Laue microdiffraction with medium-to-high energy x rays (10–30 keV) may contain double spots, one strong and one weak, for the higher-energy reflections. Some of the weaker spots originate from the back surface of the sample and are due to dynamic diffraction from a finite crystal. Others may be due to epitaxial thin films on the substrate. The intensity and position of the back-surface peaks depend on the x-ray energy, sample characteristics, and diffraction geometry. We provide a set of simple equations that can be used to calculate the separation of such peak pairs. These equations can be used to identify the peaks from the back surface of the sample. [ABSTRACT FROM AUTHOR]

We report our experiences with conducting ptychography simultaneously with the X-ray fluorescence measurement using the on-the-fly mode for efficient multi-modality imaging. We demonstrate that the periodic artifact inherent to the raster scan pattern can be mitigated using a sufficiently fine scan step size to provide an overlap ratio of >70%. This allows us to obtain transmitted phase contrast images with enhanced spatial resolution from ptychography while maintaining the fluorescence imaging with continuous-motion scans on pixelated grids. This capability will greatly improve the competence and throughput of scanning probe X-ray microscopy. [ABSTRACT FROM AUTHOR]

The article discusses the brief history and current status of Multilayer Laue lens (MLLs). Topics include MLLs as dynamically diffracting X-ray optics, lithographically produced Fresnel zone plates (FZP), creation of MLL optics by depositing a multilayer film on a substrate, and challenges for developing an X-ray microscope capable of positioning two independent MLL optics.

In this study, the sampling statistics of X-ray diffraction data obtained from polycrystalline nanopowders are studied through analytical formulations and numerical modelling. It is shown that the very large acceptance angles of crystalline nanoparticles can cause issues in computing the number of diffracting grains scattering into a given Bragg reflection. These results intimate that formulations previously tested and verified for polycrystalline aggregates with grains larger than 500 nm should be revalidated for particles with coherent scattering lengths below 10 nm. [ABSTRACT FROM AUTHOR]

The focusing performance of a multilayer Laue lens (MLL) with 43.4 mm aperture, 4 nm finest zone width and 4.2 mm focal length at 12 keV was characterized with X-rays using ptychography method. The reconstructed probe shows a full-width-at-half-maximum (FWHM) peak size of 11.2 nm. The obtained X-ray wavefront shows excellent agreement with the dynamical calculations, exhibiting aberrations less than 0.3 wave period, which ensures the MLL capable of producing a diffraction-limited focus while offering a sufficient working distance. This achievement opens up opportunities of incorporating a variety of in-situ experiments into ultra high-resolution X-ray microscopy studies. [ABSTRACT FROM AUTHOR]

The multilayer Laue lens (MLL) is a novel diffractive optic for hard X-ray nanofocusing, which is fabricated by thin film deposition techniques and takes advantage of the dynamical diffraction effect to achieve a high numerical aperture and efficiency. It overcomes two difficulties encountered in diffractive optics fabrication for focusing hard X-rays: (1) small outmost zone width and (2) high aspect ratio. Here, we will give a review on types, modeling approaches, properties, fabrication, and characterization methods of MLL optics. We show that a full-wave dynamical diffraction theory has been developed to describe the dynamical diffraction property of the MLL and has been employed to design the optimal shapes for nanofocusing. We also show a 16nm line focus obtained by a partial MLL and several characterization methods. Experimental results show a good agreement with the theoretical calculations. With the continuing development of MLL optics, we believe that an MLL-based hard x-ray microscope with true nanometer resolution is on the horizon. [ABSTRACT FROM AUTHOR]

Diffraction profiles from an Si-single-crystal strip deformed in cantilever bending are presented as a function of tip displacement and incident-beam energy. Data obtained with slit-based diffracted-beam optics contain a secondary peak in addition to the primary 004 reflection for all energies when the bending strain is finite. This secondary peak can be identified as a `mirage' peak, predicted by dynamical diffraction theory to occur in weakly deformed single-crystal samples. The integrated intensity of this mirage peak increases with increasing energy and tip displacement and exceeds the primary peak intensity at higher values. The mirage peak disappears when a monochromator is used in the diffracted-beam path. Data that show the effect of these mirage peaks on X-ray diffraction strain analysis are presented, and it is shown that a diffracted-beam monochromator may be used to eliminate these errors. [ABSTRACT FROM AUTHOR]

We report improved results for hard x-ray focusing using a multilayer Laue lens (MLL). We have measured a line focus of 16 nm width with an efficiency of 31% at a wavelength λ=0.064 nm (19.5 keV) using a partial MLL structure with an outermost zone width of 5 nm. The results are in good agreement with the theoretically predicted performance. [ABSTRACT FROM AUTHOR]

A simple and effective approach has been developed to grow silver (Ag) nanoplates on n-type gallium arsenide (GaAs) wafers through a reaction between the wafers themselves and aqueous solutions of silver nitrate at room temperature [Sun and Wiederrecht, Small 3, 1964 (2007)]. In this letter, the effect of green laser irradiation, which can efficiently excite the valence band of a GaAs substrate to form electron-hole pairs in the shallow surface region (<3 μm), on the growth of Ag nanoplates is studied. Illumination with the laser significantly depresses the growth of Ag nanoplates. In comparison, the influence of synchrotron x-rays, which can excite the deep core levels of elements and deeply penetrate (>50 μm) into GaAs lattices, on the growth of Ag nanoplates is also studied. The results indicate that the excited deep core levels can relax into electron-hole pairs in the band edges to induce similar effects to that of the green laser except that the larger area around the x-ray beam is affected to inhibit the growth of Ag nanoplates. [ABSTRACT FROM AUTHOR]

We derive a set of ptychography phase-retrieval iterative engines based on proximal algorithms originally developed in convex optimization theory, and discuss their connections with existing ones. The use of proximal operator creates a simple frame work that allows us to incorporate the effect of noise from a maximum-likelihood (ML) principle. We focus on three particular algorithms, namely proximal minimization, alternating direction method of multiplier and accelerated proximal gradient (APG). We benchmark their performance with numerical simulations, and discuss their optimal conditions for convergence and accuracy. An experimental dataset is used to demonstrate their effectiveness as well, in which case an array of cubic Au nanoparticles with a size of 50 nm is imaged. We show that with the presence of Poisson noise, a dataset with photon counts up to 104 at one detector pixel already requires ML-based methods to achieve a stable convergence. Among the three algorithms derived in this work, APG method is reported first time for its application in ptychographic reconstruction and shows superior performance in terms of both accuracy and convergence rate with a noisy dataset. [ABSTRACT FROM AUTHOR]

Multilayer Laue lenses (MLLs) are x-ray focusing optics with the potential to focus hard x-rays down to a single nanometer level. In order to achieve point focus, an MLL microscope needs to have the capability to perform tip-tilt motion of MLL optics and to hold the angular position for an extended period of time. In this work, we present a 2D tip-tilt system that can achieve an angular resolution of over 100 microdegree with a working range of 4°, by utilizing a combination of laser interferometer and mini retroreflector. The linear dimensions of the developed system are about 30 mm in all directions, and the thermal dissipation of the system during operation is negligible. Compact design and high angular resolution make the developed system suitable for MLL optics alignment in the next generation of MLL-based x-ray microscopes. [ABSTRACT FROM AUTHOR]