This work describes the instrumentation and software for microbeam scattering and structural mapping at the Life Science X-ray Scattering (LiX) beamline at NSLS-II. Using a two-stage focusing scheme, an adjustable beam size between a few micrometres and a fraction of a millimetre is produced at the sample position. Scattering data at small and wide angles are collected simultaneously on multiple Pilatus detectors. A recent addition of an in-vacuum Pilatus 900k detector, with the detector modules arranged in a C-shaped configuration, has improved the azimuthal angle coverage in the wide-angle data. As an option, fluorescence data can be collected simultaneously. Fly scans have been implemented to minimize the time interval between scattering patterns and to avoid unnecessary radiation damage to the sample. For weakly scattering samples, an in-vacuum sample environment has been developed here to minimize background scattering. Data processing for these measurements is highly sample-specific. To establish a generalized data process workflow, first the data are reduced to reciprocal coordinates at the time of data collection. The users can then quantify features of their choosing from these intermediate data and construct structural maps. As examples, results from in-vacuum mapping of onion epidermal cell walls and 2D tomographic sectioning of an intact poplar stem are presented.

The use of molten salts for large-scale solar concentrated power plants and molten salt reactors has been driving the research to better understand how metals and alloys interact with the molten salt. As the metals may undergo morphological, chemical, and structural change in molten salt environments, it is critical to understand the fundamental mechanisms in these changes. In this work, we will present how we utilized synchrotron X-ray nano-tomography to better understand the 3D morphological evolution of Ni, Cr, and their alloys in molten salt. The effects of temperature and additives in the salt on the morphological evolution will be discussed. At the higher temperature, a characteristic bicontinuous structure can form from molten salt dealloying a binary alloy. [1] This contrasts to the intergranular corrosion found in the same system reacted at a lower temperature. [2] Different additives in the salt were also found to alter the morphological changes of the alloys and can create planar corrosion, percolation dealloying, or redeposition. To complement the morphological studies by X-ray nano-tomography, a suite of X-ray and electron microscopy analyses were also carried out to better understand the chemical and structural (both short-and long-range ordering) evolution. Taking it as a multimodal approach, we will discuss how we couple the analysis from synchrotron operando X-ray absorption spectroscopy, diffraction, and imaging, as well as the multiscale imaging studies from both X-ray and electron microscopy. This work was supported as part of the Molten Salts in Extreme Environments (MSEE) Energy Frontier Research Center (EFRC), funded by the U.S. Department of Energy, Office of Science. References: [1] "Formation of three-dimensional bicontinuous structures via molten salt dealloying studied in real-time by in situ synchrotron X-ray nano-tomography" Xiaoyang Liu, Arthur Ronne*, Lin-Chieh Yu, Yang Liu, Mingyuan Ge, Cheng-Hung Lin, Bobby Layne, Phillip Halstenberg, Dmitry S. Maltsev, Alexander S. Ivanov, Stephen Antonelli, Sheng Dai, Wah-Keat Lee, Shannon M. Mahurin, Anatoly I. Frenkel, James F. Wishart, Xianghui Xiao & Yu-chen Karen Chen-Wiegart* Nature Communications (2021), DOI: 10.1038/s41467-021-23598-8 [2] "Visualizing time-dependent microstructural and chemical evolution during molten salt corrosion of Ni-20Cr model alloy using correlative quasi in situ TEM and in situ synchrotron X-ray nano-tomography" Kaustubh Bawane, Xiaoyang Liu, Ruchi Gakhar, Michael Woods, Mingyuan Ge, Xianghui Xiao, Wah-Keat Lee, Philip Halstenberg, Sheng Dai, Shannon Mahurin, Simon M. Pimblott, James F. Wishart, Yu-chen Karen Chen-Wiegart*, Lingfeng He* Corrosion Science (2021), DOI: 10.1016/j.corsci.2021.109962

A correction in the paper by Lazo et al. [(2021). J. Synchrotron Rad. 28, 1649–1661] is made.

We report the instrumentation and software for microbeam scattering and structural mapping at the Life Science Xray Scattering (LiX) beamline at NSLS-II.Using a two-stage focusing scheme, we produce an adjustable beam size between a few microns and a fraction of a millimeter at the sample position.Scattering data at small and wide angles are collected simultaneously on multiple Pilatus detectors.A recent addition of a Pilatus 900K detector, with the detector modules arranged in a C-shaped configuration, improves the azimuthal angle coverage in the wide-angle data.Fluorescence data can be collected simultaneously.Fly scans have been implemented to minimize time interval between data frames and unnecessary radiation damage to the sample.For samples that do not produce strong scattering, we have developed an in-vacuum sample environment to minimize background scattering.Data processing for these measurements is highly sample-specific.We have implemented a python library that helps users reduce data into reciprocal coordinates, from which they can then quantify features from these intermediate data and construct structural maps.Research examples will be presented.

Here we present two robotic sample changers integrated into the experimental stations for the macromolecular crystallography (MX) beamlines AMX and FMX, and the biological small-angle scattering (bioSAXS) beamline LiX. They enable fully automated unattended data collection and remote access to the beamlines. The system designs incorporate high-throughput, versatility, highcapacity, resource sharing and robustness. All systems are centered around a sixaxis industrial robotic arm coupled with a force torque sensor and in-house end effectors (grippers). They have the same software architecture and the facility standard EPICS-based BEAST alarm system. The MX system is compatible with SPINE bases and Unipucks. It comprises a liquid nitrogen dewar holding 384 samples (24 Unipucks) and a stay-cold gripper, and utilizes machine vision software to track the sample during operations and to calculate the final mount position on the goniometer. The bioSAXS system has an in-house engineered sample storage unit that can hold up to 360 samples (20 sample holders) which keeps samples at a user-set temperature (277 K to 300 K). The MX systems were deployed in early 2017 and the bioSAXS system in early 2019.

During the COVID-19 pandemic, synchrotron beamlines were forced to limit user access. Performing routine measurements became a challenge. At the Life Science X-ray Scattering (LiX) beamline, new instrumentation and mail-in protocols have been developed to remove the access barrier to solution scattering measurements. Our efforts took advantage of existing instrumentation and coincided with the larger effort at NSLS-II to support remote measurements. Given the limited staff-user interaction for mail-in measurements, additional software tools have been developed to ensure data quality, to automate the adjustments in data processing, as users would otherwise rely on the experience of the beamline staff, and produce a summary of the initial assessments of the data. This report describes the details of these developments.

Three-dimensional bicontinuous porous materials formed by dealloying contribute significantly to various applications including catalysis, sensor development and energy storage. This work studies a method of molten salt dealloying via real-time in situ synchrotron three-dimensional X-ray nano-tomography. Quantification of morphological parameters determined that long-range diffusion is the rate-determining step for the dealloying process. The subsequent coarsening rate was primarily surface diffusion controlled, with Rayleigh instability leading to ligament pinch-off and creating isolated bubbles in ligaments, while bulk diffusion leads to a slight densification. Chemical environments characterized by X-ray absorption near edge structure spectroscopic imaging show that molten salt dealloying prevents surface oxidation of the metal. In this work, gaining a fundamental mechanistic understanding of the molten salt dealloying process in forming porous structures provides a nontoxic, tunable dealloying technique and has important implications for molten salt corrosion processes, which is one of the major challenges in molten salt reactors and concentrated solar power plants.

Solution small angle X‐ray scattering (SAXS) is a method to characterize the behavior of particles such as proteins and protein complexes in solution. Information about particle size and shape as well as oligomeric state can be determined from the 1D scattering profiles. The life sciences X‐ray scattering (LiX) beamline at NSLSII operates in two modes: I) X‐ray imaging and II) solution scattering (BioSAXS). Here, we discuss the types of BioSAXS measurements performed, automation, remote collection, data processing and examples of user data. Static SAXS measurements are high throughput and managed with a sample handler, with room for up to 360 samples organized into 18‐well holders. Each holder contains two rows that are connected to separate channels of a flow cell that aligns with the X‐ray beam. As the sample flows into the channel and is illuminated by the X‐ray beam, small angle (SAXS) and wide angle (WAXS) data is collected simultaneously on two detectors with a q‐range of 0.006Å‐1 to 3.2 Å‐1. This type of measurement requires pure, monodisperse sample and for the case when mixed populations exist, such as dimers and monomers, static SAXS will produce poor data quality. Therefore, size exclusion chromatography coupled with SAXS (SEC‐SAXS) should be considered to separate each species. At LiX, the center flow channel is connected to an HPLC system, which allows for seamless integration of SEC‐SAXS into the workflow without having to make changes to the beamline hardware setup. Once data is collected, it is packaged into HDF5 format and automatically processed. Data is transferred to users via Globus. We now offer remote collection and users can ship samples in holders or 96‐well plates. Samples sent in plates are loaded into an Opentrons liquid handling system and transferred into sample holders. Additionally, having the Opentrons allow us to manipulate sample conditions through dilution, mixing and/or screening right before measurement.

Small angle X‐ray scattering is an important tool that reveals the behavior of proteins in their native environment. The scattering pattern produced from a SAXS experiment represents an average of all conformations present in the solution. Since most proteins in our body function in a solution environment, SAXS data can reveal additional biologically relevant states of a molecule or molecular complex. Furthermore, SAXS provides data about the shape and size of the molecule of interest and is a complementary technique to other structural methods. Combining SAXS data with X‐ray crystallography, NMR or Cryo‐EM can lead to a more robust understanding of the species being studied. High quality SAXS data can be used to build ab initio low resolution bead models, which provide a 3D envelope of your molecule. Here at the life sciences X‐ray scattering beamline (LiX), we collect data by flowing sample through the X‐ray path in a 3 channel flow cell. As the sample enters the X‐ray path, the simultaneous collection of SAXS and wide angle X‐ray scattering (WAXS) is obtained via a 3 detector setup. The detector setup has a q‐range of 0.006Å−1 to 3.2 Å−1, primarily to obtain scattering data from the water peak to normalize buffer subtraction. Automated sample handling at LiX allows for collection of up to 360 samples, packaging of data and processing. One challenge in obtaining high quality SAXS data is preparation of pure, monodisperse samples. For these complicated samples that have multiple species, our in‐line HPLC system seamlessly integrates with our beamline for SEC‐SAXS (size‐exclusion chromatography‐SAXS), and increases the chances of obtaining a more pure, monodisperse sample immediately before data collection.Support or Funding InformationLiX beamline is part of the Life Science Biomedical Technology Research resource, co‐funded by the National Institute of General Medical Sciences (NIGMS) under grant P41 GM111244 and by the DOE Office of Biological and Environmental Research under grant KP1605010, with additional support from NIH under grant S10 OD012331. The operation of NSLS2 is supported by US Department of Energy, Office of Basic Energy Sciences, under contract No. DE‐SC0012704.

A versatile, compact heater designed at National Synchrotron Light Source-II for in situ X-ray nano-imaging in a full-field transmission X-ray microscope is presented. Heater design for nano-imaging is challenging, combining tight spatial constraints with stringent design requirements for the temperature range and stability. Finite-element modeling and analytical calculations were used to determine the heater design parameters. Performance tests demonstrated reliable and stable performance, including maintaining the exterior casing close to room temperature while the heater is operating at above 1100°C, a homogenous heating zone and small temperature fluctuations. Two scientific experiments are presented to demonstrate the heater capabilities: (i) in situ 3D nano-tomography including a study of metal dealloying in a liquid molten salt extreme environment, and (ii) a study of pore formation in icosahedral quasicrystals. The progression of structural changes in both studies were clearly resolved in 3D, showing that the new heater enables powerful capabilities to directly visualize and quantify 3D morphological evolution of materials under real conditions by X-ray nano-imaging at elevated temperature during synthesis, fabrication and operation processes. This heater design concept can be applied to other applications where a precise, compact heater design is required.