We will present the design for the In-Situ Nanoprobe (ISN) beamline that is being developed as part of the Upgrade of the APS storage ring with an MBA magnetic lattice. The ISN will provide large working distance of 60 mm for in-situ and operando environments, and a small spot of 20 nm (25 keV) for imaging materials with small defects and functional components. To achieve both long working distance and small spot size, Kirkpatrick-Baez mirrors will be used as nanofocusing optics. The major contrast mechanisms will be XRF imaging for chemical characterization ptychography for transmission imaging with sub-10 nm resolution. Auxiliary diffraction capabilities will allow monitoring of phase change during in-situ studies. To achieve the demagnification required to achieve small spot sizes, the ISN instrument will be placed at a distance of 220 m from the x-ray source, in a satellite building outside the APS storage ring. The ISN will provide hard x-rays with photon energy between 4.8 keV and 30 keV, enabling access to the absorption edges of to most elements in the periodic system. The MBA lattice and insertion devices, coupled with the high reflectivity of the K-B mirror system, provide a very high coherent flux of above 4*1012 Ph/s at 5 keV, and 6*1012 Ph/s at 30 keV. This allows hierarchical imaging of large samples with very small spot size, as well as multidimensional imaging, such as 3D imaging and temperature change, or 2D imaging with change of several environmental parameters. The ISN will provide flow of fluids, gases, and variable temperature.
As X-ray imaging is pushed further into the nanoscale, the sample deformations due to the increased radiation levels or mechanical instabilities of the microscopes become more apparent, leading to challenges in realizing high-resolution microscopy under these conditions. Here we propose a distributed optimization solver for imaging of samples at the nanoscale. Our approach solves the tomography and ptychography problems jointly with projection data alignment, nonrigid sample deformation correction, and regularization. Applicability of the method is demonstrated on experimental data sets from the Transmission X-ray Microscope, and the hard X-ray nanoprobe.
X-ray computed tomography (CT) is a promising technique for three-dimensional imaging of batteries, electrolyzers and fuel cells. Operando techniques rely significantly on reactor design, where the operando cell should approximate the actual device. Furthermore, nano- and micro-scale hierarchical materials are used to convert or store electrochemical energy. Imaging with the single scale or synchrotron beamline provides only sliver of information needed. Carbon and ionomer materials that are used as bulk materials in the electrochemical devices are soft and phase-contrast imaging is required.
We present our micro- and nano-X-ray CT reactors designs for polymer electrolyte fuel cells (PEFCs), electrolyzers, and micro X-ray CT operando pouch cell for battery. With the PEFC hardware we control temperature, relative humidity, pressure of gasses, as well as current density. By imaging the PEFCs at various current densities we are able to observe physical phenomena of membrane swelling with relative humidity increase and formation and removal of liquid water from the cell. With nano X-ray CT we are able to combine morphology with x-ray absorption near edge structure (XANES) to elucidate the oxidation state of the catalyst within the active porous layer. Using phase-contrast we are able to distinguish between liquid water and carbon phases. For electrolyzers, understanding formation and removal of oxygen bubbles, which is sub-second transport phenomena is critical. We combine X-ray CT with sub-second X-ray radiography to understand this transient process. For the batteries, we have developed a high throughput pouch cell design for x-ray CT imaging featuring 1 cm diameter active area.
The Transmission X-ray Microscope (TXM) at beamline 32-ID-C of the Advanced Photon Source (APS) is a high throughput instrument with high spatial resolution for operando nano-tomography experiments [1]. Recently, a flexural nanopositioning stage system has been designed, and constructed at the APS for a set of JTECTM Kirkpatrick-Baez (KB) mirrors to be installed at the beamline 32-ID-C station. It will focus X-ray down to a 15-20 nm focal spot that will serve as a point source for projection microscopy. Many flexural stages in the stage system are using the same designs developed by APS for the beamline 34-ID-E [2]. However, the new stage system configuration is optimized for the operation conditions at the APS 32-ID-C to accommodate large nano-tomography sample stages. The experiences gained from this new flexural nanopositioning stage system design will benefit designs of K-B mirror nanofocusing stages for other x-ray nanoprobe beamline instruments at the APS-Upgrade project, especially for the In-Situ Nanoprobe instrument design. The mechanical design of the flexural stages, as well as its preliminary mechanical test results with laser interferometer are described in this paper.
The Advanced Photon Source Upgrade (APS-U) project will construct several new, best-in-class beamlines and enhancements to existing beamlines to exploit the massive increase in coherent flux enabled by the new storage ring lattice. APS-U will also enhance several existing beamlines to boost their performance. X-ray tomography is a common imaging mode for several of these beamlines, so there is demand for the highest-precision rotation of the sample. For example, the In Situ Nanoprobe (ISN, 19-ID), a next-generation hard x-ray nanoprobe, will use x-ray fluorescence tomography and ptychographic 3D imaging as key imaging modes with a spot size of 20 nm. It will require <100 nm runout and single-micro-radian wobble errors of the rotation stage to achieve full 3D resolution. Such precise requirements for a rotation stage can be achieved with air bearing rotation stages. However, this approach puts constraints on sample positioning design in terms of the sample environment (air bearing stages are generally not vacuum compatible) and the large mass of air bearing rotation stages. Mechanical bearing stages do not equal the precision runout/wobble specifications of air bearings. In order to use mechanical stages and approach air bearing level precision, the errors of the mechanical stage have to be measured precisely. We have then designed a metrology system using interferometer or capacitive sensors for the nanopositioning support lab as a diagnostic tool and to be portable for quality assurance testing of stages at the beamline.
The detection sensitivity of synchrotron-based X-ray techniques has been largely improved due to the ever increasing source brightness, which have significantly advanced ex-situ and in-situ research for energy materials, such as lithium-ion batteries. However, the strong beam-matter interaction arisen from the high beam flux can significantly modify the material structure. The parasitic beam-induced effect inevitably interferes with the intrinsic material property, which brings difficulties in interpreting experimental results, and therefore requires comprehensive evaluation. Here we present a quantitative in-situ study of the beam-effect on one electrode material Ag2VO2PO4 using four different X-ray probes with different radiation dose rate. The material system we reported exhibits interesting and reversible radiation-induced thermal and chemical reactions, which was further evaluated under electron microscopy to illustrate the underlying mechanism. The work we presented here will provide a guideline in using synchrotron X-rays to distinguish the materials’ intrinsic behavior from extrinsic structure changed induced by X-rays, especially in the case of in-situ and operando study where the materials are under external field of either temperature or electric field.
KEYWORDS: X-rays, Microscopes, Materials science, Spatial resolution, Zone plates, Systems engineering, Software development, Reconstruction algorithms, Data acquisition, 3D acquisition
A new Transmission X-ray Microscope (TXM), optimized for in-situ nano-tomography experiments, has been designed and built at the Advanced Photon Source (APS). The instrument has been in operation for the last two years and is supporting users over large fields of Science, from energy storage and material science to natural sciences. The flexibility of our X-ray microscope design permits evolutionary geometries and can accommodate relatively heavy, up to 5 kg, and bulky in-situ cells while ensuring high spatial resolution, which is expected to improve steadily thanks to the support of the RD program led by the APS-Upgrade project on Fresnel zone plates (FZP). The robust sample stack, designed with minimum degrees of freedom shows a stability better than 4 nm rms at the sample location. The TXM operates with optics fabricated in-house. A spatial resolution of 30 nm per voxel has been demonstrated when the microscope operates with a 60 nm outermost zone width FZP with a measured efficiency of 18% at 8 keV. 20 nm FZP are also currently available and should be in routine use within the next few months once a new matching condenser is produced. In parallel, efficiency is being improved with opto-mechanical engineering (FZP stacking system) and software developments (more efficient reconstruction algorithms combined with different data acquisition schemes), enabling 3D dynamic studies when sample evolution occurs within a couple of tens of seconds.
The Sub-micron Resolution X-ray spectroscopy (SRX) beamline will benefit from the ultralow emittance of the National
Synchrotron Light Source II to address a wide variety of scientific applications studying heterogeneous systems at the
sub-micrometer scale. This work focuses on the KB branch (ΔE: 4.65-28 keV). Its main optical components include a
horizontally focusing mirror forming an adjustable secondary source, a horizontally deflecting monochromator and two
sets of Kirkpatrick-Baez mirrors as focusing optics of two distinct inline stations for operations requiring either high flux
or high resolution. In the first approach, the beamline layout was optimized with ray-tracing calculations involving
Shadowvui computer codes. As a result, the location and characteristics of optics were specified for achieving either the
most intense or the smallest monochromatic beam possible on the target (1013 ph/s or 1012 ph/s respectively in a 500 nm
or 65 nm focal spot). At the nanoprobe station, the diffraction limited focusing of X-rays is governed by the beam
coherence. Hence, a classical geometric approach is not anymore adapted. To get reliable estimates of the Nanoprobe
performances, a wavefront propagation study was performed using Synchrotron Radiation Workshop (SRW) code. At
7.2 keV, calculations show an intense (1012 ph/s) 67 nm wide diffraction limited spot achieved with actual metrological
data of mirrors.
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