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In ferromagnets, domain patterns can be controlled globally using magnetic fields or spin-polarized currents. In contrast, the local control of the magnetization on the nanometer length scale remains challenging. Here, we demonstrate how magnetic domain patterns in a Tm-doped yttrium iron garnet (Tm:YIG) thin film with perpendicular magnetic anisotropy can be permanently and locally imprinted by high intensity photon pulses of a hard x-ray transient grating (XTG). Micromagnetic simulations provide a qualitative understanding of the observed changes in the orientation of magnetic domains in Tm:YIG and XTG-induced changes. The presented results offer a route for the local manipulation of the magnetic state using hard XTG. [ABSTRACT FROM AUTHOR]

X-ray ptychography, a scanning coherent diffraction imaging technique, is one of the most used techniques at synchrotron facilities for high resolution imaging, with applications spanning from life science to nano-electronics. In the recent years there has been a great effort to make the technique faster to enable high throughput nanoscale imaging. Here we apply a fast ptychography scanning method to image in 3D 10 6 μ m 3 of brain-like phantom at 3 kHz, in a 7 h acquisition with a resolution of 270 nm. We then present the latest advances in fast ptychography by showing 2D images acquired at 110 kHz by combining the fast-acquisition scheme with a high-acquisition rate prototype detector from DECTRIS Ltd. We finally review the experimental outcome and discuss the prospective use of fast ptychography schemes for the investigation of mm 3 size samples of brain-like phantom, by extrapolating the current results to the high coherent flux scenario of diffraction limited storage rings. [ABSTRACT FROM AUTHOR]

Understanding and control of thermal transport in solids at the nanoscale are crucial in engineering and enhance the properties of a new generation of optoelectronic, thermoelectric and photonic devices. In this regard, semiconductor superlattice structures provide a unique platform to study phenomena associated with phonon propagations in solids such as heat conduction. Transient X‐ray diffraction can directly probe atomic motions and therefore is among the rare techniques sensitive to phonon dynamics in condensed matter. Here, optically induced transient heat conduction in GaAs/AlAs superlattice structures is studied using the EIGER2 detector. Benchmark experiments have been performed at the Austrian SAXS beamline at Elettra–Sincrotrone Trieste operated in the hybrid filling mode. This work demonstrates that drifts of experimental conditions, such as synchrotron beam fluctuations, become less essential when utilizing the EIGER2 double‐gating mode which results in a faster acquisition of high‐quality data and facilitates data analysis and data interpretation. [ABSTRACT FROM AUTHOR]

The ability to utilize a hybrid-photon-counting detector to its full potential can significantly influence data quality, data collection speed, as well as development of elaborate data acquisition schemes. This paper facilitates the optimal use of EIGER2 detectors by providing theory and practical advice on (i) the relation between detector design, technical specifications and operating modes, (ii) the use of corrections and calibrations, and (iii) new acquisition features: a doublegating mode, 8-bit readout mode for increasing temporal resolution, and lines region-of-interest readout mode for frame rates up to 98 kHz. Examples of the implementation and application of EIGER2 at several synchrotron sources (ESRF, PETRA III/DESY, ELETTRA, AS/ANSTO) are presented: high accuracy of high-throughput data in serial crystallography using hard X-rays; suppressing higher harmonics of undulator radiation, improving peak shapes, increasing data collection speed in powder X-ray diffraction; faster ptychography scans; and cleaner and faster pump-and-probe experiments. [ABSTRACT FROM AUTHOR]

In situ small‐ and wide‐angle scattering experiments at synchrotrons often result in massive quantities of data within just seconds. Especially during such beamtimes, processing of the acquired data online, without appreciable delay, is key to obtaining feedback on the failure or success of the experiment. This had led to the development of SAXSDOG, a Python‐based environment for real‐time azimuthal integration of large‐area scattering images. The software is primarily designed for dedicated data pipelines: once a scattering image is transferred from the detector onto the storage unit, it is automatically integrated and pre‐evaluated using integral parameters within milliseconds. The control and configuration of the underlying server‐based processes is achieved via a graphical user interface, SAXSLEASH, which visualizes the resulting 1D data together with integral classifiers in real time. SAXSDOG further includes a portable 'take‐home' version for users that runs on standalone computers, enabling its use in laboratories or at the preferred workspace. [ABSTRACT FROM AUTHOR]

Atomically defined assemblies of dye molecules (such as H and J aggregates) have been of interest for more than 80 years because of the emergence of collective phenomena in their optical spectra1–3, their coherent long-range energy transport, their conceptual similarity to natural light-harvesting complexes4,5, and their potential use as light sources and in photovoltaics. Another way of creating versatile and controlled aggregates that exhibit collective phenomena involves the organization of colloidal semiconductor nanocrystals into long-range-ordered superlattices6. Caesium lead halide perovskite nanocrystals7–9 are promising building blocks for such superlattices, owing to the high oscillator strength of bright triplet excitons10, slow dephasing (coherence times of up to 80 picoseconds) and minimal inhomogeneous broadening of emission lines11,12. So far, only single-component superlattices with simple cubic packing have been devised from these nanocrystals13. Here we present perovskite-type (ABO3) binary and ternary nanocrystal superlattices, created via the shape-directed co-assembly of steric-stabilized, highly luminescent cubic CsPbBr3 nanocrystals (which occupy the B and/or O lattice sites), spherical Fe3O4 or NaGdF4 nanocrystals (A sites) and truncated-cuboid PbS nanocrystals (B sites). These ABO3 superlattices, as well as the binary NaCl and AlB2 superlattice structures that we demonstrate, exhibit a high degree of orientational ordering of the CsPbBr3 nanocubes. They also exhibit superfluorescence—a collective emission that results in a burst of photons with ultrafast radiative decay (22 picoseconds) that could be tailored for use in ultrabright (quantum) light sources. Our work paves the way for further exploration of complex, ordered and functionally useful perovskite mesostructures.Through precise structural engineering, perovskite nanocrystals are co-assembled with other nanocrystal materials to form a range of binary and ternary perovskite-type superlattices that exhibit superfluorescence. [ABSTRACT FROM AUTHOR]

The design of novel carbon dots with ad hoc properties requires a comprehensive understanding of their formation mechanism, which is a complex task considering the number of variables involved, such as reaction time, structure of precursors or synthetic protocol employed. Herein, we systematically investigated the formation of carbon nanodots by tracking structural, chemical and photophysical features during the hydrothermal synthesis. We demonstrate that the formation of carbon nanodots consists of 4 consecutive steps: (i) aggregation of small organic molecules, (ii) formation of a dense core with an extended shell, (iii) collapse of the shell and (iv) aromatization of the core. In addition, we provide examples of routes towards tuning the core-shell design, synthesizing five novel carbon dots that all consist of an electron-dense core covered by an amine rich ligand shell. Studying the formation processes of carbon nanodots remains crucial for understanding their properties and chemical structure. Here, the authors investigate the steps involved in their formation process and provide examples for tuning the core-shell design. [ABSTRACT FROM AUTHOR]

A new setup for picosecond pump–probe X‐ray scattering at the Austrian SAXS beamline at Elettra‐Sincrotrone Trieste is presented. A high‐power/high‐repetion‐rate laser has been installed on‐site, delivering UV/VIS/IR femtosecond‐pulses in‐sync with the storage ring. Data acquisition is achieved by gating a multi‐panel detector, capable of discriminating the single X‐ray pulse in the dark‐gap of the Elettra hybrid filling mode. Specific aspects of laser‐ and detection‐synchronization, on‐line beam steering as well protocols for spatial and temporal overlap of laser and X‐ray beam are also described. The capabilities of the setup are demonstrated by studying transient heat‐transfer in an In/Al/GaAs superlattice structure and results are confirmed by theoretical calculations. [ABSTRACT FROM AUTHOR]

The availability of the hybrid photon counting (HPC) technology for noise-free X-ray detection was a landmark achievement for the synchrotron community: the advent of HPC detectors not only led to a significant improvement of the acquired data quality [[1]], but also enabled new experiments in previously unreachable time-domains [[2]]. For typical diffraction experiments, such as small-angle X-ray scattering (SAXS) or powder X-ray diffraction (PXRD), the STREAM interface is widely used for on-the-fly azimuthal integration, which enables real-time analysis of the acquired data. The STREAM2 interface for multi-image energy-sensitive X-ray data collection The recent EIGER2 Feature Upgrade [[10]] included a new low-latency data interface for its users: STREAM2. [Extracted from the article]

Some new considerations on the model-free shape retrieval of inorganic nanocrystals based on the evaluation of averaged dummy atom models obtained from small-angle X-ray scattering data are presented. Scattering curves for shapes commonly found in inorganic nanocrystal systems were computed, from which dummy atom models were reconstructed using DAMMIN and DAMAVER. Cross sectional analysis methods were applied to allow a quantitative interpretation of these models, where special focus was directed towards the measurement of discrete model dimensions. By a quantitative comparison of the obtained models with the initial geometries, the limits of the proposed evaluation techniques were tested. Further, the proposed methods were utilized to study the influence of the accessible scattering vector as well as the effect of increasing size distributions on models retrieved by DAMMIN and DAMAVER. The results confirm the usefulness of these ab initio shape-retrieval methods for slightly polydisperse systems. Finally, the practicability of the proposed techniques is demonstrated on an ensemble of chemically synthesized colloidal bismuth nanocrystals. [ABSTRACT FROM AUTHOR]

Hydrogen-bonded pigments are remarkably stable high-crystal lattice energy organic solids. Here a lesser-known family of compounds, the epindolidiones, which demonstrates electronic transport with extraordinary stability, even in highly demanding aqueous environments, is reported. Hole mobilities in the range 0.05-1 cm2 V-1 s-1 can be achieved, with lower electron mobilities of up to 0.1 cm2 V-1 s-1. To help understand charge transport in epindolidiones, X-ray diffraction is used to solve the crystal structure of 2,8-difluoroepindolidione and 2,8-dichloroepindolidione. Both derivatives crystallize with a linear-chain H-bonding lattice featuring two-dimensional π-π stacking. Powder diffraction indicates that the unsubstituted epindolidione has very similar crystallinity. All types of epindolidiones measured here display strong low-energy optical emission originating from excimeric states, which coexists with higher-energy fluorescence. This can be exploited in light-emitting diodes, which show the same hybrid singlet and low-energy excimer electroluminescence. Low-voltage FETs are fabricated with epindolidione, which operate reliably under repeated cyclic tests in different ionic solutions within the pH range 3-10 without degradation. Finally, in order to overcome the insolubility of epindolidiones in organic solvents, a chemical procedure is devised to allow solution-processing via the introduction of suitable thermolabile solubilizing groups. This work shows the versatile potential of epindolidione pigments for electronics applications. [ABSTRACT FROM AUTHOR]