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Schematic representation of the scanning x-ray microscopy capabilities available at the Hard X-ray Nanoprobe (HXN) beamline.
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... scanning x-ray microscopy beamlines (such as that illustrated in Figure 1), monochromatic x-rays are focused to produce a nanobeam. X-ray imaging can be performed by scanning a sample across the focused beam, and the resulting x-ray signals are collected to visualize (with the use of a variety of contrast mechanisms) elemental, structural, and chemical details of the sample. Fluorescent x-rays, for example, are emitted by excited electrons in the sample and provide a unique fingerprint of its elemental composition. Bragg-diffracted x-rays yield detailed informa- tion on the crystalline phase, crystallite (i.e., grain) orientation, and strain distribution. To obtain comprehensive structural and chemical images of a sample, scanning x-ray instruments must be capable of making simultaneous measurements of these different signal types. Over the last decade, the scientific requirements for scanning x-ray microscopy beamlines at synchrotron facilities have in- creased dramatically, i.e., there is a need for increasingly high spatial resolutions. 1–4 The Hard X-ray Nanoprobe (HXN) beamline at the National Synchrotron Light Source II (NSLS-II) 5 is the newest addition to the growing number of nanoprobes. This beamline was developed with unprecedented goals for hard x-ray resolutions. The initial performance target for the HXN is to enable x-ray imaging experiments at a resolution of 10nm, with an ultimate goal of about 1nm. In addition, an alterna- tive imaging method—known as ptychography—is offered at the HXN beamline. In ptychography, coherently diffracted signals are used to mathematically reconstruct the nanostructure of a sample. Spatial resolutions that are better than the size of the focused beam can be achieved with this methodology. We have undertaken several substantial development efforts to assure the high-performance scanning x-ray microscopy capabilities of the new HXN beamline. For instance, we have produced nanofocusing optics that allow 10nm resolutions to be achieved, 6–8 and we have constructed a versatile x-ray microscope. 9, 10 We use a new class of x-ray nanofocusing optics—known as multilayer Laue lenses (MLLs)—to achieve our particularly high spatial resolutions. We will offer pt y cho- graphic analysis 11 at the HXN beamline for transmitted x-rays (to visualize the electronic density of non-crystalline samples) and for Bragg-diffracted x-rays (to visualize the strain distribution within crystalline grains). Once we have completed the HXN commissioning, the beamline will operate over an en- ergy range of 6–25keV. The focused beam will have a flux of 5 10 8 photons per second over the 10 10nm 2 beam. Spectro- microscopy and 3D imaging capabilities will also be offered. We conceived MLLs to overcome the well-known aspect-ratio limit of x-ray zone plates (i.e., that prevents ultra-high resolutions being achieved), but while retaining good efficiency. With MLLs we are able to avoid this aspect-ratio limit because these lenses are fabricated using thin-film deposition of depth-graded multilayers. We section and thin the MLL thin film with the use of a focused ion beam. In this way we are able to obtain the op- timal thickness for the lens. A scanning electron microscopy image of a sectioned MLL is shown in Figure 2(A). In our setup, monochromatic x-rays are focused to a point—see Figure 2(B)— by a pair of orthogonally arranged MLLs. A close-up view of the MLL microscope module for our HXN x-ray microscope is shown in Figure 2(C). This module has com- pact dimensions—about the size of a small coffeemaker—and a closed-loop feedback mechanism that uses laser interferometers. These characteristics of the MLL microscope module allow us to achieve sub-nanometer positioning stability with the microscope. The HXN x-ray microscope also houses a zone plate microscope module. We operate this module with a spatial resolution of 30nm, but it does offer more scientifically flexible capabilities. Of our HXN beamline imaging techniques that are illustrated in Figure 1, the scanning fluorescence imaging capability is now fully commissioned and available to general users. One of the first sets of nanoscale images that we produced at the beamline, in April 2015, is shown in Figure 3. For these measurements, we used a platinum (Pt) resolution test pattern—with a circular structure array that was 20nm wide and 200nm tall— as a sample. In addition, we made the measurements with the use of monochromatic x-rays at 12keV and a synchrotron electron beam current of 50mA. Our measured image of the Pt L-edge (spectroscopic measure of electronic structure) clearly shows the individual circular structures. Our preliminary analysis of the results indicates that a range of spatial resolutions (about 12–15nm) was achieved. It is also important to note that we produced this image using a fly-scanning method. 11 In this approach, we obtain each horizontal line of the image by con- tinuously scanning the sample, while simultaneously triggering the detectors. We required a total of 40 minutes to collect this image, which consists of 101 101 pixels (5nm per pixel and 200ms exposure time per pixel). By October 2015 we will have a higher electron beam current (150mA) and will have completed further instrument optimizations. At that point we will be able to obtain a comparable image in about five minutes. We have designed, built, and recently commissioned the HXN beamline, which offers high-performance scanning x-ray microscopy at unprecedented resolutions. Our development efforts include a new class of x-ray nanofocusing optics, known as multilayer Laue lenses. Our first nanoscale x-ray fluorescence images were successfully obtained with the beamline in April 2015. Additional scientific capabilities will be offered on the HXN beamline as we progress through our rapid commissioning schedule. In October 2015, a differential phase contrast imaging technique 12 will become available. This will allow the analysis of transmitted x-rays so that nanoscale morphology and elemental distribution of a sample can be imaged simultaneously. In 2016, we plan for transmission ptychography, nanodiffraction, and Bragg ptychography to be commissioned and subsequently made available for general user ...
Context 2
... scanning x-ray microscopy beamlines (such as that illustrated in Figure 1), monochromatic x-rays are focused to produce a nanobeam. X-ray imaging can be performed by scanning a sample across the focused beam, and the resulting x-ray signals are collected to visualize (with the use of a variety of contrast mechanisms) elemental, structural, and chemical details of the sample. Fluorescent x-rays, for example, are emitted by excited electrons in the sample and provide a unique fingerprint of its elemental composition. Bragg-diffracted x-rays yield detailed informa- tion on the crystalline phase, crystallite (i.e., grain) orientation, and strain distribution. To obtain comprehensive structural and chemical images of a sample, scanning x-ray instruments must be capable of making simultaneous measurements of these different signal types. Over the last decade, the scientific requirements for scanning x-ray microscopy beamlines at synchrotron facilities have in- creased dramatically, i.e., there is a need for increasingly high spatial resolutions. 1–4 The Hard X-ray Nanoprobe (HXN) beamline at the National Synchrotron Light Source II (NSLS-II) 5 is the newest addition to the growing number of nanoprobes. This beamline was developed with unprecedented goals for hard x-ray resolutions. The initial performance target for the HXN is to enable x-ray imaging experiments at a resolution of 10nm, with an ultimate goal of about 1nm. In addition, an alterna- tive imaging method—known as ptychography—is offered at the HXN beamline. In ptychography, coherently diffracted signals are used to mathematically reconstruct the nanostructure of a sample. Spatial resolutions that are better than the size of the focused beam can be achieved with this methodology. We have undertaken several substantial development efforts to assure the high-performance scanning x-ray microscopy capabilities of the new HXN beamline. For instance, we have produced nanofocusing optics that allow 10nm resolutions to be achieved, 6–8 and we have constructed a versatile x-ray microscope. 9, 10 We use a new class of x-ray nanofocusing optics—known as multilayer Laue lenses (MLLs)—to achieve our particularly high spatial resolutions. We will offer pt y cho- graphic analysis 11 at the HXN beamline for transmitted x-rays (to visualize the electronic density of non-crystalline samples) and for Bragg-diffracted x-rays (to visualize the strain distribution within crystalline grains). Once we have completed the HXN commissioning, the beamline will operate over an en- ergy range of 6–25keV. The focused beam will have a flux of 5 10 8 photons per second over the 10 10nm 2 beam. Spectro- microscopy and 3D imaging capabilities will also be offered. We conceived MLLs to overcome the well-known aspect-ratio limit of x-ray zone plates (i.e., that prevents ultra-high resolutions being achieved), but while retaining good efficiency. With MLLs we are able to avoid this aspect-ratio limit because these lenses are fabricated using thin-film deposition of depth-graded multilayers. We section and thin the MLL thin film with the use of a focused ion beam. In this way we are able to obtain the op- timal thickness for the lens. A scanning electron microscopy image of a sectioned MLL is shown in Figure 2(A). In our setup, monochromatic x-rays are focused to a point—see Figure 2(B)— by a pair of orthogonally arranged MLLs. A close-up view of the MLL microscope module for our HXN x-ray microscope is shown in Figure 2(C). This module has com- pact dimensions—about the size of a small coffeemaker—and a closed-loop feedback mechanism that uses laser interferometers. These characteristics of the MLL microscope module allow us to achieve sub-nanometer positioning stability with the microscope. The HXN x-ray microscope also houses a zone plate microscope module. We operate this module with a spatial resolution of 30nm, but it does offer more scientifically flexible capabilities. Of our HXN beamline imaging techniques that are illustrated in Figure 1, the scanning fluorescence imaging capability is now fully commissioned and available to general users. One of the first sets of nanoscale images that we produced at the beamline, in April 2015, is shown in Figure 3. For these measurements, we used a platinum (Pt) resolution test pattern—with a circular structure array that was 20nm wide and 200nm tall— as a sample. In addition, we made the measurements with the use of monochromatic x-rays at 12keV and a synchrotron electron beam current of 50mA. Our measured image of the Pt L-edge (spectroscopic measure of electronic structure) clearly shows the individual circular structures. Our preliminary analysis of the results indicates that a range of spatial resolutions (about 12–15nm) was achieved. It is also important to note that we produced this image using a fly-scanning method. 11 In this approach, we obtain each horizontal line of the image by con- tinuously scanning the sample, while simultaneously triggering the detectors. We required a total of 40 minutes to collect this image, which consists of 101 101 pixels (5nm per pixel and 200ms exposure time per pixel). By October 2015 we will have a higher electron beam current (150mA) and will have completed further instrument optimizations. At that point we will be able to obtain a comparable image in about five minutes. We have designed, built, and recently commissioned the HXN beamline, which offers high-performance scanning x-ray microscopy at unprecedented resolutions. Our development efforts include a new class of x-ray nanofocusing optics, known as multilayer Laue lenses. Our first nanoscale x-ray fluorescence images were successfully obtained with the beamline in April 2015. Additional scientific capabilities will be offered on the HXN beamline as we progress through our rapid commissioning schedule. In October 2015, a differential phase contrast imaging technique 12 will become available. This will allow the analysis of transmitted x-rays so that nanoscale morphology and elemental distribution of a sample can be imaged simultaneously. In 2016, we plan for transmission ptychography, nanodiffraction, and Bragg ptychography to be commissioned and subsequently made available for general user ...
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Citations
... Use these partial derivatives within the Adam algorithm [37] to calculate ,˜, and˜. ...
... In our ptychography simulations, we use a 2D probe profile experimentally measured from a Fresnel zone plate x-ray focusing optic at the HXN beamline at NSLS-II [37], of size 100 × 100 pixels at focus (with each pixel of size 1 nm). We threshold to zero any pixels in the probe below an intensity cutoff of 2% of the maximum intensity to reduce aliasing in the simulated diffraction patterns. ...
Recent advances in phase-retrieval-based x-ray imaging methods have demonstrated the ability to reconstruct 3D distortion vector fields within a nanocrystal by using coherent diffraction information from multiple crystal Bragg reflections. However, these works do not provide a solution to the challenges encountered in imaging lattice distortions in crystals with significant defect content that result in phase wrapping. Moreover, these methods only apply to isolated crystals smaller than the x-ray illumination, and therefore cannot be used for imaging of distortions in extended crystals. We introduce multi-peak Bragg ptychography which addresses both challenges via an optimization framework that combines stochastic gradient descent and phase unwrapping methods for robust image reconstruction of lattice distortions and defects in extended crystals. Our work uses modern automatic differentiation toolsets so that the method is easy to extend to other settings and easy to implement in high-performance computers. This work is particularly timely given the broad interest in using the increased coherent flux in fourth-generation synchrotrons for innovative material research.
... The distribution of elements was mapped using nano-Mii (Nanoscale Multimodal Imaging Instrument) at beamline 3-ID (HXN) at the National Synchrotron Light Source II (Fig. 1A). Beamline 3-ID provides a scanning X-ray microscope capable of multimodal imaging including absorption, fluorescence, differential phase contrast, and ptychography 28 . In this study, a 12 keV incident beam was focused to a sub-15 nm spot (14 nm horizontal and 12 nm vertical) using Multilayer Laue Lenses (MLLs). ...
Abstract X-ray Fluorescence (XRF) microscopy is a growing approach for imaging the trace element concentration, distribution, and speciation in biological cells at the nanoscale. Moreover, three-dimensional nanotomography provides the added advantage of imaging subcellular structure and chemical identity in three dimensions without the need for staining or sectioning of cells. To date, technical challenges in X-ray optics, sample preparation, and detection sensitivity have limited the use of XRF nanotomography in this area. Here, XRF nanotomography was used to image the elemental distribution in individual E. coli bacterial cells using a sub-15 nm beam at the Hard X-ray Nanoprobe beamline (HXN, 3-ID) at NSLS-II. These measurements were simultaneously combined with ptychography to image structural components of the cells. The cells were embedded in small (3–20 µm) sodium chloride crystals, which provided a non-aqueous matrix to retain the three-dimensional structure of the E. coli while collecting data at room temperature. Results showed a generally uniform distribution of calcium in the cells, but an inhomogeneous zinc distribution, most notably with concentrated regions of zinc at the polar ends of the cells. This work demonstrates that simultaneous two-dimensional ptychography and XRF nanotomography can be performed with a sub-15 nm beam size on unfrozen biological cells to co-localize elemental distribution and nanostructure simultaneously.
... Due to the fabrication process using thin-film deposition, MLLs can achieve almost unlimited aspect ratio when compared to the zone plates, yielding higher focusing efficiency. Several MLL-based microscopes have been constructed and deployed, pushing 2D imaging resolution down to 13 nm [19][20][21][22][23]. ...
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.
... The optics and microscope system to generate such a focus and perform the scanning probe measurement are described elsewhere. 4,8,32,33 The sample used in the experiment contained gold nanoparticles, prepared by depositing a 20 nm thick layer of a gold film onto a silicon substrate and then annealing the film at 800 C for 8 h. The gold film became dewetted to isolated sub-micron crystals with various widths and thicknesses. ...
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.
... Such an optic has achieved a record 15 nm × 15 nm focus at 0.1 nm wavelength for routine experimental use. 12 Intense research is underway worldwide to reach the ultimate focus. ...
The development of new materials and improvements of existing ones are at the root of the spectacular recent developments of new technologies for synchrotron storage rings and free-electron laser sources. This holds true for all relevant application areas, from electron guns to undulators, X-ray optics, and detectors. As demand grows for more powerful and efficient light sources, efficient optics, and high-speed detectors, an overview of ongoing materials research for these applications is timely. In this article, we focus on the most exciting and demanding areas of materials research and development for synchrotron radiation optics and detectors. Materials issues of components for synchrotron and free-electron laser accelerators are briefly discussed. The articles in this issue expand on these topics.
... Typical MLL-based microscopes require a multitude of independent degrees of motion within a few millimeters of working space to perform 2D imaging and mapping with nm-scale spatial resolution. A number of MLL microscopes [50][51][52] have been built and commissioned at synchrotron sources within the last few years; all utilize stateof-the-art piezo-based positioning systems, fi ber-optic interferometry for positional feedback, and power-saving algorithms to minimize thermal drifts. Vibrational levels less than 2 nm and thermal drifts less than 2 nm/hour have been reported during commissioning of MLL-based systems [50]. ...
... A number of MLL microscopes [50][51][52] have been built and commissioned at synchrotron sources within the last few years; all utilize stateof-the-art piezo-based positioning systems, fi ber-optic interferometry for positional feedback, and power-saving algorithms to minimize thermal drifts. Vibrational levels less than 2 nm and thermal drifts less than 2 nm/hour have been reported during commissioning of MLL-based systems [50]. Measurements with sub-20 nm spatial resolution are now routinely performed at NSLS-II and are available for user operation. ...
X-rays are intrinsically capable of being used for the study of non-periodic objects with atomic resolution, with high penetration, in applied electromagnetic fields, and in fluids and gases. For direct imaging via nanofocused X-ray beams, reflective [1], refractive [2], and diffractive [3, 4] optics are used in various approaches for high-resolution imaging. Diffractive X-ray optics are endowed with the highest numerical aperture, in principle allowing focusing of X-rays to sub-nanometer dimensions. Lithographically produced Fresnel zone plates (FZP) find broad deployment around the globe, in both nanofocusing and full-field imaging approaches, and have, for many years, been workhorse optics in both synchrotron-based and laboratory-based X-ray imaging systems [4]. A FZP consists of a series of radially symmetric rings, which are known as Fresnel zones, which alternate between transparent and opaque. Radiation traversing into the FZP diffracts around the opaque zones, which are placed in an arrangement wh...
... 49 These beamlines, for example, the Hard X-Ray Nanoprobe Facility at the National Synchrotron Light Source II at Brookhaven National Laboratory, are also combining a multitude of different scattering, diffraction, and imaging techniques. 50 At the same time, synchrotron sources, including freeelectron lasers, have also been upgraded to perform at their extremes, delivering diffraction-limited, coherent beams and ultrashort time scales. Specifi c sample environments, such as high-pressure apparatus, chemical reactors, and thermomechanical processors have been developed and are complemented by automated, smart, and comprehensive computing power and algorithms for data analysis. ...
Synchrotron radiation has evolved tremendously in recent decades in sources, instrumentation, and applications in materials studies. This article provides background and an introduction to the state of the art of synchrotron research as it relates to materials research, including an overview of the articles in this MRS Bulletin issue, which focus on Laue microdiffraction, high-energy x-ray diffraction on battery materials, synchrotron radiation in high-pressure research, x-ray dark-field microscopy, and x-ray absorption spectroscopy applied to energy research. The modern approach of displaying diffraction data in reciprocal-space units and the distinction between spectroscopy and diffraction are summarized. Applications and technologies are continuously developing toward technical and optical limits, combining multiple methods for an even brighter future for this field. It is now time for expert groups to begin applying multiple and different kinds of quantum beams, such as neutrons, muons, electrons, and ions, complementary to synchrotron radiation for more efficient and effective characterization of materials.
In situ and operando measurement techniques combined with nanoscale resolution have proven invaluable in multiple fields of study. We argue that evaluating device performance as well as material behavior by correlative X-ray microscopy with <100 nm resolution can radically change the approach for optimizing absorbers, interfaces and full devices in solar cell research. In this article, we thoroughly discuss the measurement technique of X-ray beam induced current and point out fundamental differences between measurements of wafer-based silicon and thin-film solar cells. Based on reports of the last years, we showcase the potential that X-ray microscopy measurements have in combination with in situ and operando approaches throughout the solar cell lifecycle: from the growth of individual layers to the performance under operating conditions and degradation mechanisms. Enabled by new developments in synchrotron beamlines, the combination of high spatial resolution with high brilliance and a safe working distance allows for the insertion of measurement equipment that can pave the way for a new class of experiments. Applied to photovoltaics research, we highlight today’s opportunities and challenges in the field of nanoscale X-ray microscopy, and give an outlook on future developments.
We have developed an experimental approach to bond two independent linear Multilayer Laue Lenses (MLLs) together. A monolithic MLL structure was characterized using ptychography at 12 keV photon energy, and we demonstrated 12 nm and 24 nm focusing in horizontal and vertical directions, respectively. Fabrication of 2D MLL optics allows installation of these focusing elements in more conventional microscopes suitable for x-ray imaging using zone plates, and opens easier access to 2D imaging with high spatial resolution in the hard x-ray regime.
