Publications by authors named "Evgeny Nazaretski"

23 Publications

  • Page 1 of 1

Tunable hard x-ray nanofocusing with Fresnel zone plates fabricated using deep etching.

Optica 2020 May;7(5):410-416

Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.

Fresnel zone plates are widely used for x-ray nanofocusing, due to their ease of alignment and energy tunability. Their spatial resolution is limited in part by their outermost zone width , while their efficiency is limited in part by their thickness . We demonstrate the use of Fresnel zone plate optics for x-ray nanofocusing with = 16 nm outermost zone width and a thickness of about = 1.8 μm (or an aspect ratio of 110) with an absolute focusing efficiency of 4.7% at 12 keV, and 6.2% at 10 keV. Using partially coherent illumination at 12 keV, the zone plate delivered a FWHM focus of 46 × 60 nm at 12 keV, with the first order coherent mode in a ptychographic reconstruction showing a probe size of 16 nm FWHM. These optics were fabricated using a combination of metal assisted chemical etching and atomic layer deposition for the diffracting structures, and silicon wafer back-thinning to produce optics useful for real applications. This approach should enable new higher resolution views of thick materials, especially when energy tunability is required.
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http://dx.doi.org/10.1364/OPTICA.387445DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7720910PMC
May 2020

Metrology of a Focusing Capillary Using Optical Ptychography.

Sensors (Basel) 2020 Nov 12;20(22). Epub 2020 Nov 12.

National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA.

The focusing property of an ellipsoidal monocapillary has been characterized using the ptychography method with a 405 nm laser beam. The recovered wavefront gives a 12.5×10.4μm2 focus. The reconstructed phase profile of the focused beam can be used to estimate the height error of the capillary surface. The obtained height error shows a Gaussian distribution with a standard deviation of 1.3 μm. This approach can be used as a quantitative tool for evaluating the inner functional surfaces of reflective optics, complementary to conventional metrology methods.
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http://dx.doi.org/10.3390/s20226462DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7697805PMC
November 2020

Micromachined Silicon Platform for Precise Assembly of 2D Multilayer Laue Lenses for High-Resolution X-ray Microscopy.

Micromachines (Basel) 2020 Oct 15;11(10). Epub 2020 Oct 15.

National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA.

We report on a developed micromachined silicon platform for the precise assembly of 2D multilayer Laue lenses (MLLs) for high-resolution X-ray microscopy. The platform is 10 × 10 mm and is fabricated on ~500 µm thick silicon wafers through multiple steps of photolithography and deep reactive-ion etching. The platform accommodates two linear MLLs in a pre-defined configuration with precise angular and lateral position control. In this work, we discuss the design and microfabrication of the platform, and characterization regarding MLLs assembly, position control, repeatability, and stability. The results demonstrate that a micromachined platform can be used for the assembly of a variety of MLLs with different dimensions and optical parameters. The angular misalignment of 2D MLLs is well controlled in the range of the designed accuracy, down to a few millidegrees. The separation distance between MLLs is adjustable from hundreds to more than one thousand micrometers. The use of the developed platform greatly simplifies the alignment procedure of the MLL optics and reduces the complexity of the X-ray microscope. It is a significant step forward for the development of monolithic 2D MLL nanofocusing optics for high-resolution X-ray microscopy.
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http://dx.doi.org/10.3390/mi11100939DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7602850PMC
October 2020

Ptychographic X-ray speckle tracking with multi-layer Laue lens systems.

J Appl Crystallogr 2020 Aug 8;53(Pt 4):927-936. Epub 2020 Jul 8.

DESY, Notkestrasse 85, 22607 Hamburg, Germany.

The ever-increasing brightness of synchrotron radiation sources demands improved X-ray optics to utilize their capability for imaging and probing biological cells, nano-devices and functional matter on the nanometre scale with chemical sensitivity. Hard X-rays are ideal for high-resolution imaging and spectroscopic applications owing to their short wavelength, high penetrating power and chemical sensitivity. The penetrating power that makes X-rays useful for imaging also makes focusing them technologically challenging. Recent developments in layer deposition techniques have enabled the fabrication of a series of highly focusing X-ray lenses, known as wedged multi-layer Laue lenses. Improvements to the lens design and fabrication technique demand an accurate, robust, and at-wavelength characterization method. To this end, a modified form of the speckle tracking wavefront metrology method has been developed. The ptychographic X-ray speckle tracking method is capable of operating with highly divergent wavefields. A useful by-product of this method is that it also provides high-resolution and aberration-free projection images of extended specimens. Three separate experiments using this method are reported, where the ray path angles have been resolved to within 4 nrad with an imaging resolution of 45 nm (full period). This method does not require a high degree of coherence, making it suitable for laboratory-based X-ray sources. Likewise, it is robust to errors in the registered sample positions, making it suitable for X-ray free-electron laser facilities, where beam-pointing fluctuations can be problematic for wavefront metrology.
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http://dx.doi.org/10.1107/S1600576720006925DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7401788PMC
August 2020

2D MEMS-based multilayer Laue lens nanofocusing optics for high-resolution hard x-ray microscopy.

Opt Express 2020 Jun;28(12):17660-17671

We report on the development of 2D integrated multilayer Laue lens (MLL) nanofocusing optics used for high-resolution x-ray microscopy. A Micro-Electro-Mechanical-Systems (MEMS) - based template has been designed and fabricated to accommodate two linear MLL optics in pre-aligned configuration. The orthogonality requirement between two MLLs has been satisfied to a better than 6 millidegrees level, and the separation along the x-ray beam direction was controlled on a micrometer scale. Developed planar 2D MLL structure has demonstrated astigmatism free point focus of ∼14 nm by ∼13 nm in horizontal and vertical directions, respectively, at 13.6 keV photon energy. Approaching 10 nm resolution with integrated 2D MLL optic is a significant step forward in applications of multilayer Laue lenses for high-resolution hard x-ray microscopy and their adoption by the general x-ray microscopy community.
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http://dx.doi.org/10.1364/OE.389555DOI Listing
June 2020

Perovskite neural trees.

Nat Commun 2020 05 7;11(1):2245. Epub 2020 May 7.

School of Materials Engineering, Purdue University, West Lafayette, IN, 47907, USA.

Trees are used by animals, humans and machines to classify information and make decisions. Natural tree structures displayed by synapses of the brain involves potentiation and depression capable of branching and is essential for survival and learning. Demonstration of such features in synthetic matter is challenging due to the need to host a complex energy landscape capable of learning, memory and electrical interrogation. We report experimental realization of tree-like conductance states at room temperature in strongly correlated perovskite nickelates by modulating proton distribution under high speed electric pulses. This demonstration represents physical realization of ultrametric trees, a concept from number theory applied to the study of spin glasses in physics that inspired early neural network theory dating almost forty years ago. We apply the tree-like memory features in spiking neural networks to demonstrate high fidelity object recognition, and in future can open new directions for neuromorphic computing and artificial intelligence.
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http://dx.doi.org/10.1038/s41467-020-16105-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7206050PMC
May 2020

Design, characterization, and performance of a hard x-ray transmission microscope at the National Synchrotron Light Source II 18-ID beamline.

Rev Sci Instrum 2019 May;90(5):053701

National Synchrotron Light Source-II, Brookhaven National Laboratory, Upton, New York 11973, USA.

A transmission X-ray microscope has been designed and commissioned at the 18-ID Full-field X-ray Imaging beamline at the National Synchrotron Light Source II. This instrument operates in the 5-11 keV range, and, with the current set of optics, is capable of 30 nm spatial resolution imaging, with a field of view of about 40 μm. For absorption contrast, the minimum exposure time for a single projection image is about 20 ms and an entire 3D tomography data set can be acquired in under 1 min. The system enables tomographic reconstructions with sub-50 nm spatial resolution without the use of markers on the sample or corrections for rotation run-outs.
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http://dx.doi.org/10.1063/1.5088124DOI Listing
May 2019

X-ray focusing with efficient high-NA multilayer Laue lenses.

Light Sci Appl 2018 23;7:17162. Epub 2018 Mar 23.

Alfred-Wegener Institute, Helmholtz Center for Polar and Marine Research, Bussestr. 27, Bremerhaven 27570, Germany.

Multilayer Laue lenses are volume diffraction elements for the efficient focusing of X-rays. With a new manufacturing technique that we introduced, it is possible to fabricate lenses of sufficiently high numerical aperture (NA) to achieve focal spot sizes below 10 nm. The alternating layers of the materials that form the lens must span a broad range of thicknesses on the nanometer scale to achieve the necessary range of X-ray deflection angles required to achieve a high NA. This poses a challenge to both the accuracy of the deposition process and the control of the materials properties, which often vary with layer thickness. We introduced a new pair of materials-tungsten carbide and silicon carbide-to prepare layered structures with smooth and sharp interfaces and with no material phase transitions that hampered the manufacture of previous lenses. Using a pair of multilayer Laue lenses (MLLs) fabricated from this system, we achieved a two-dimensional focus of 8.4 × 6.8 nm at a photon energy of 16.3 keV with high diffraction efficiency and demonstrated scanning-based imaging of samples with a resolution well below 10 nm. The high NA also allowed projection holographic imaging with strong phase contrast over a large range of magnifications. An error analysis indicates the possibility of achieving 1 nm focusing.
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http://dx.doi.org/10.1038/lsa.2017.162DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6060042PMC
March 2018

Resolving 500 nm axial separation by multi-slice X-ray ptychography.

Acta Crystallogr A Found Adv 2019 Mar 12;75(Pt 2):336-341. Epub 2019 Feb 12.

National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA.

Multi-slice X-ray ptychography offers an approach to achieve images with a nanometre-scale resolution from samples with thicknesses larger than the depth of field of the imaging system by modeling a thick sample as a set of thin slices and accounting for the wavefront propagation effects within the specimen. Here, we present an experimental demonstration that resolves two layers of nanostructures separated by 500 nm along the axial direction, with sub-10 nm and sub-20 nm resolutions on two layers, respectively. Fluorescence maps are simultaneously measured in the multi-modality imaging scheme to assist in decoupling the mixture of low-spatial-frequency features across different slices. The enhanced axial sectioning capability using correlative signals obtained from multi-modality measurements demonstrates the great potential of the multi-slice ptychography method for investigating specimens with extended dimensions in 3D with high resolution.
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http://dx.doi.org/10.1107/S2053273318017229DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6396394PMC
March 2019

Large Aperture and Wedged Multilayer Laue Lens for X-ray Nanofocusing.

J Nanosci Nanotechnol 2019 01;19(1):575-584

National Synchrotron Light Source II, Brookhaven National Laboratory, Upton NY 11973, USA.

Diffraction optics fabricated from multilayers offer an intriguing alternative to lithography-based zone plates due to their advantages of virtually limitless aspect ratio and extremely small feature size. However, other issues, intrinsic to thin-film deposition, such as film stress and deposition rate instability, for example, limit the total achievable aperture. Over the last decade, Multilayer Laue Lens (MLLs) have progressed from a mere curiosity with initial aperture sizes in the 3-10 m range, to real beamline-deployed optics with apertures in the 40-50 m range (X. Huang, et al., 3, 3562 (2013); E. Nazaretski, et al., 85, 033707 (2014); E. Nazaretski, et al., 24, 1113 (2017)). By optimizing deposition conditions and incorporating new materials, MLLs have now broken the 100 m thickness milestone. A flat WSi₂/Al-Si MLL with a deposition thickness of 102 m, the largest MLL to date, is reviewed. New large aperture wedged MLLs (wMLL), which were first fabricated by APS in 2006 using the WSi2/Si material system, are presented which demonstrate high focusing efficiency across a broad energy range. These results confirm findings by other groups who have also independently fabricated wMLL (A. J. Morgan, et al., 5, 9892 (2015); S. Bajt, et al., 7, 17162 (2017)) based on a similar material system.
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http://dx.doi.org/10.1166/jnn.2019.16479DOI Listing
January 2019

High-speed raster-scanning synchrotron serial microcrystallography with a high-precision piezo-scanner.

J Synchrotron Radiat 2018 Sep 23;25(Pt 5):1362-1370. Epub 2018 Aug 23.

Photon Sciences, Brookhaven National Laboratory, Upton, NY 11973, USA.

The Frontier Microfocus Macromolecular Crystallography (FMX) beamline at the National Synchrotron Light Source II with its 1 µm beam size and photon flux of 3 × 10 photons s at a photon energy of 12.66 keV has reached unprecedented dose rates for a structural biology beamline. The high dose rate presents a great advantage for serial microcrystallography in cutting measurement time from hours to minutes. To provide the instrumentation basis for such measurements at the full flux of the FMX beamline, a high-speed, high-precision goniometer based on a unique XYZ piezo positioner has been designed and constructed. The piezo-based goniometer is able to achieve sub-100 nm raster-scanning precision at over 10 grid-linepairs s frequency for fly scans of a 200 µm-wide raster. The performance of the scanner in both laboratory and serial crystallography measurements up to the maximum frame rate of 750 Hz of the Eiger 16M's 4M region-of-interest mode has been verified in this work. This unprecedented experimental speed significantly reduces serial-crystallography data collection time at synchrotrons, allowing utilization of the full brightness of the emerging synchrotron radiation facilities.
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http://dx.doi.org/10.1107/S1600577518010354DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6140394PMC
September 2018

Nanospectroscopy Captures Nanoscale Compositional Zonation in Barite Solid Solutions.

Sci Rep 2018 Aug 29;8(1):13041. Epub 2018 Aug 29.

National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA.

Scientists have long suspected that compositionally zoned particles can form under far-from equilibrium precipitation conditions, but their inferences have been based on bulk solid and solution measurements. We are the first to directly observe nanoscale trace element compositional zonation in <10 µm-sized particles using X-ray fluorescence nanospectroscopy at the Hard X-ray Nanoprobe (HXN) Beamline at National Synchrotron Light Source II (NSLS-II). Through high-resolution images, compositional zonation was observed in barite (BaSO) particles precipitated from aqueous solution, in which Sr cations as well as HAsO anions were co-precipitated into (Ba,Sr)SO or Ba(SO,HAsO) solid solutions. Under high salinity conditions (NaCl ≥ 1.0 M), bands contained ~3.5 to ~5 times more trace element compared to the center of the particle formed in early stages of particle growth. Quantitative analysis of Sr and As fractional substitution allowed us to determine that different crystallographic growth directions incorporated trace elements to different extents. These findings provide supporting evidence that barite solid solutions have great potential for trace element incorporation; this has significant implications for environmental and engineered systems that remove hazardous substances from water.
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http://dx.doi.org/10.1038/s41598-018-31335-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6115454PMC
August 2018

Measuring Three-Dimensional Strain and Structural Defects in a Single InGaAs Nanowire Using Coherent X-ray Multiangle Bragg Projection Ptychography.

Nano Lett 2018 02 24;18(2):811-819. Epub 2018 Jan 24.

Materials Science Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.

III-As nanowires are candidates for near-infrared light emitters and detectors that can be directly integrated onto silicon. However, nanoscale to microscale variations in structure, composition, and strain within a given nanowire, as well as variations between nanowires, pose challenges to correlating microstructure with device performance. In this work, we utilize coherent nanofocused X-rays to characterize stacking defects and strain in a single InGaAs nanowire supported on Si. By reconstructing diffraction patterns from the 21̅1̅0 Bragg peak, we show that the lattice orientation varies along the length of the wire, while the strain field along the cross-section is largely unaffected, leaving the band structure unperturbed. Diffraction patterns from the 011̅0 Bragg peak are reproducibly reconstructed to create three-dimensional images of stacking defects and associated lattice strains, revealing sharp planar boundaries between different crystal phases of wurtzite (WZ) structure that contribute to charge carrier scattering. Phase retrieval is made possible by developing multiangle Bragg projection ptychography (maBPP) to accommodate coherent nanodiffraction patterns measured at arbitrary overlapping positions at multiple angles about a Bragg peak, eliminating the need for scan registration at different angles. The penetrating nature of X-ray radiation, together with the relaxed constraints of maBPP, will enable the in operando imaging of nanowire devices.
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http://dx.doi.org/10.1021/acs.nanolett.7b04024DOI Listing
February 2018

Achieving diffraction-limited nanometer-scale X-ray point focus with two crossed multilayer Laue lenses: alignment challenges.

Opt Express 2017 Oct;25(21):25234-25242

We discuss misalignment-induced aberrations in a pair of crossed multilayer Laue lenses used for achieving a nanometer-scale x-ray point focus. We thoroughly investigate the impacts of two most important contributions, the orthogonality and the separation distance between two lenses. We find that misalignment in the orthogonality results in astigmatism at 45° and other inclination angles when coupled with a separation distance error. Theoretical explanation and experimental verification are provided. We show that to achieve a diffraction-limited point focus, accurate alignment of the azimuthal angle is required to ensure orthogonality between two lenses, and the required accuracy is scaled with the ratio of the focus size to the aperture size.
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http://dx.doi.org/10.1364/OE.25.025234DOI Listing
October 2017

Hard x-ray scanning imaging achieved with bonded multilayer Laue lenses.

Opt Express 2017 Apr;25(8):8698-8704

We report scanning hard x-ray imaging with a monolithic focusing optic consisting of two multilayer Laue lenses (MLLs) bonded together. With optics pre-characterization and accurate control of the bonding process, we show that a common focal plane for both MLLs can be realized at 9.317 keV. Using bonded MLLs, we obtained a scanning transmission image of a star test pattern with a resolution of 50 × 50 nm2. By applying a ptychography algorithm, we obtained a probe size of 17 × 38 nm2 and an object image with a resolution of 13 × 13 nm2. The significant reduction in alignment complexity for bonded MLLs will greatly extend the application range in both scanning and full-field x-ray microscopies.
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http://dx.doi.org/10.1364/OE.25.008698DOI Listing
April 2017

Multimodality hard-x-ray imaging of a chromosome with nanoscale spatial resolution.

Sci Rep 2016 Feb 5;6:20112. Epub 2016 Feb 5.

National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA.

We developed a scanning hard x-ray microscope using a new class of x-ray nano-focusing optic called a multilayer Laue lens and imaged a chromosome with nanoscale spatial resolution. The combination of the hard x-ray's superior penetration power, high sensitivity to elemental composition, high spatial-resolution and quantitative analysis creates a unique tool with capabilities that other microscopy techniques cannot provide. Using this microscope, we simultaneously obtained absorption-, phase-, and fluorescence-contrast images of Pt-stained human chromosome samples. The high spatial-resolution of the microscope and its multi-modality imaging capabilities enabled us to observe the internal ultra-structures of a thick chromosome without sectioning it.
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http://dx.doi.org/10.1038/srep20112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4742846PMC
February 2016

Achieving hard X-ray nanofocusing using a wedged multilayer Laue lens.

Opt Express 2015 May;23(10):12496-507

We report on the fabrication and the characterization of a wedged multilayer Laue lens for x-ray nanofocusing. The lens was fabricated using a sputtering deposition technique, in which a specially designed mask was employed to introduce a thickness gradient in the lateral direction of the multilayer. X-ray characterization shows an efficiency of 27% and a focus size of 26 nm at 14.6 keV, in a good agreement with theoretical calculations. These results indicate that the desired wedging is achieved in the fabricated structure. We anticipate that continuous development on wedged MLLs will advance x-ray nanofocusing optics to new frontiers and enrich capabilities and opportunities for hard X-ray microscopy.
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http://dx.doi.org/10.1364/OE.23.012496DOI Listing
May 2015

Fly-scan ptychography.

Sci Rep 2015 Mar 13;5:9074. Epub 2015 Mar 13.

National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA.

We report an experimental ptychography measurement performed in fly-scan mode. With a visible-light laser source, we demonstrate a 5-fold reduction of data acquisition time. By including multiple mutually incoherent modes into the incident illumination, high quality images were successfully reconstructed from blurry diffraction patterns. This approach significantly increases the throughput of ptychography, especially for three-dimensional applications and the visualization of dynamic systems.
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http://dx.doi.org/10.1038/srep09074DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4357920PMC
March 2015

A high-precision instrument for mapping of rotational errors in rotary stages.

J Synchrotron Radiat 2014 Nov 2;21(Pt 6):1367-9. Epub 2014 Oct 2.

Photon Sciences, Brookhaven National Laboratory, Upton, NY 11973, USA.

A rotational stage is a key component of every X-ray instrument capable of providing tomographic or diffraction measurements. To perform accurate three-dimensional reconstructions, runout errors due to imperfect rotation (e.g. circle of confusion) must be quantified and corrected. A dedicated instrument capable of full characterization and circle of confusion mapping in rotary stages down to the sub-10 nm level has been developed. A high-stability design, with an array of five capacitive sensors, allows simultaneous measurements of wobble, radial and axial displacements. The developed instrument has been used for characterization of two mechanical stages which are part of an X-ray microscope.
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http://dx.doi.org/10.1107/S160057751401618XDOI Listing
November 2014

Design and characterization of a compact nano-positioning system for a portable transmission x-ray microscope.

Rev Sci Instrum 2013 Dec;84(12):123702

Institute of Physics, Academia Sinica, Taipei 11529, Taiwan.

We have designed and constructed a compact nano-positioning system for a Portable Transmission X-ray Microscope (PTXM). We introduce a concept of PTXM and adopt modular approach which implements identical nano-motion platforms to perform manipulation of PTXM components. Modular design provides higher stiffness of the system and allows for reduction of relative thermal drifts between individual constituents of the PTXM apparatus, ensuring a high degree of stability for nanoscale x-ray imaging. We have measured relative thermal drifts between two identical modules to be as low as 15 nm/h, sufficient to perform nanoscale imaging by TXM. Spatial resolution achieved by developed linear piezo stages was measured to be 3 nm with repeatability of 20 nm over 1 mm travel range.
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http://dx.doi.org/10.1063/1.4838635DOI Listing
December 2013

11 nm hard X-ray focus from a large-aperture multilayer Laue lens.

Sci Rep 2013 Dec 20;3:3562. Epub 2013 Dec 20.

National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA.

The focusing performance of a multilayer Laue lens (MLL) with 43.4 μm 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.
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http://dx.doi.org/10.1038/srep03562DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3868962PMC
December 2013

Oxidation of PtNi nanoparticles studied by a scanning X-ray fluorescence microscope with multi-layer Laue lenses.

Nanoscale 2013 Aug 15;5(16):7184-7. Epub 2013 May 15.

Department of Advanced Engineering Materials, Chosun University, Gwangju 501-759, Republic of Korea.

We report a study of the oxidation process of individual PtNi nanoparticles (NPs) conducted with a novel scanning multi-layer Laue lens X-ray microscope. The elemental maps reveal that alloyed PtNi NPs were transformed into Pt/NiO core-shell NPs by thermal oxidation. The observations furthermore indicate that a coalescence of Pt/NiO core-shell NPs occurred during oxidation.
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http://dx.doi.org/10.1039/c3nr00396eDOI Listing
August 2013

Quantitative x-ray phase imaging at the nanoscale by multilayer Laue lenses.

Sci Rep 2013 ;3:1307

National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA.

For scanning x-ray microscopy, many attempts have been made to image the phase contrast based on a concept of the beam being deflected by a specimen, the so-called differential phase contrast imaging (DPC). Despite the successful demonstration in a number of representative cases at moderate spatial resolutions, these methods suffer from various limitations that preclude applications of DPC for ultra-high spatial resolution imaging, where the emerging wave field from the focusing optic tends to be significantly more complicated. In this work, we propose a highly robust and generic approach based on a Fourier-shift fitting process and demonstrate quantitative phase imaging of a solid oxide fuel cell (SOFC) anode by multilayer Laue lenses (MLLs). The high sensitivity of the phase to structural and compositional variations makes our technique extremely powerful in correlating the electrode performance with its buried nanoscale interfacial structures that may be invisible to the absorption and fluorescence contrasts.
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http://dx.doi.org/10.1038/srep01307DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3575587PMC
August 2013
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