Elucidating the structure-property relationship of mesocrystals requires understanding the mutual arrangement of the nanoparticles within their assembly. This, therefore, requires characterization techniques capable of non-destructively distinguishing the shape, position, and orientation of the individual constituent nanoparticles in three dimensions. This detailed structural analysis is achieved here by using coherent X-ray diffraction imaging (CXDI) complemented with angular X-ray cross-correlation analysis (AXCCA) and electron microscopy. Three mesocrystals are examined, each assembled from different-sized gold octahedral nanoparticles and functionalized with ω-thiol-terminated polystyrene (PS-SH) of different molecular weights. AXCCA provides information regarding the ensemble-averaged mesocrystal lattice structure, such as the symmetry, unit cell parameters, and the presence of orientational disorder. CXDI complementarily enables the precise identification of the shape and positions of individual nanoparticles as well as revealing any structural defects. Our results show that each mesocrystal has a nearly perfect lattice structure with minimal defects and exhibits an increased strain toward the surface.

Phase transitions are governed by both intrinsic and extrinsic heterogeneities, yet capturing their spatio-temporal dynamics remains a challenge. While ultrafast techniques track phase changes on femtosecond timescales, the spatial complexity and stochastic nature of the processes often remain hidden. Here, we present an experimental approach that combines well-established ultrafast hard-X-ray diffraction with a propagating strain pulse as a universal and non-invasive probe. This ultrafast X-ray sonography can capture the spatio-temporal phase heterogeneity in great detail by resolving the phase-specific strain response. We apply this approach to the antiferromagnetic-to-ferromagnetic magneto-structural phase transition in FeRh and identify the ferromagnetic phase to nucleate at the surface as narrow columnar domains of approximately 30 nm diameter. Besides reconciling the diverse experimental results in the literature on FeRh, X-ray sonography offers a versatile platform for investigating a wide range of phase transitions accompanied by structural changes.

In a coherent scattering experiment, one of the important experimental parameters is the speckle visibility, which can be changed by adjusting the size of the X-ray beam on the sample. Focussing optics provide therefore a convenient tool to increase the speckle visibility, while simultaneously increasing the flux density and thus the dose on the sample. At the Coherence Applications Beamline P10 different focussing options are used to optimize this interplay of dose and speckle visibility for a given experiment. Using compound refractive lenses, three different realizations are presented using a lens-to-sample distance of 0.45, 1.6 and 10.8 m. The resulting focal spot sizes range from around 1 µ m × 1 µ m to around 15 µ m × 7 µ m (horizontal × vertical direction).

We report on the feasibility of Fourier transform holography in the hard X-ray regime using a Free Electron Laser source. Our study shows successful single and multi-pulse holographic reconstructions of the nanostructures. We observe beam-induced heating of the sample exposed to the intense X-ray pulses leading to reduced visibility of the holographic reconstructions. Furthermore, we extended our study exploring the feasibility of recording holographic reconstructions with hard X-ray split-and-delay optics. Our study paves the way towards studying dynamics at sub-nanosecond timescales and atomic lengthscales.

Inconel 718 is one type of nickel-based alloy used for a large range of applications, including gas turbines and aeroengines components. Although mechanical and thermodynamic properties of this material have been deeply studied in the past years, a method able to investigate local properties of the thin white layer formed on the alloy surface after machining remains challenging. Here, a 90 nm X-ray beam is used to probe the local strain, crystal orientation, and chemical composition of grains in the white layer. Data reveals mosaicity induced by the tool during machining. The high spatial resolution, combined with crystal lattice sensitivity, shows that the average grain size is around 30 nm throughout the white layer, while the strain is anisotropic nearest to the surface. Results provide new insights on the basic properties of the white layer in super alloys, revealing important information about the impact of finish machining which might help to explain fatigue and cracking formation on these materials during their usage phase.

The controlled manipulation of spins on ultrashort timescales is among the most promising solutions for novel high-speed and low-power-consumption spintronic and magnetic recording applications. To do so, terahertz (THz) light pulses can be used to drive coherent magnetization dynamics in ferromagnetic thin films. We were able to resolve these dynamics on the nanoscale employing THz-pump x-ray resonant magnetic scattering from the labyrinth-type domain network of a Co/Pt multilayer with perpendicular magnetic anisotropy. Our results reveal THz-driven ultrafast demagnetization as well as coherent local magnetization oscillations at the THz fundamental frequency of 2.5 THz. We observe a temporal lag between femtosecond demagnetization and the start of the coherent magnetization oscillations that can be understood by a time-dependent damping. The dynamics of the domain and domain-wall contributions are found to be highly correlated, suggesting the applicability of THz spin control in magnetic nanostructures.

The advent of diffraction limited sources and developments in detector technology opens up new possibilities for the study of materials in situ and operando. Coherent X-ray diffraction techniques such as coherent X-ray diffractive imaging (CXDI) and X-ray photon correlation spectroscopy (XPCS) are capable for this purpose and provide complementary information, although due to signal-to-noise requirements, their simultaneous demonstration has been limited. Here, we demonstrate a strategy for the simultaneous use of CXDI and XPCS to study in situ the Brownian motion of colloidal gold nanoparticles of 200 nm diameter suspended in a glycerol-water mixture. We visualize the process of agglomeration, examine the spatiotemporal space accessible with the combination of techniques, and demonstrate CXDI with 22 ms temporal resolution.

Terahertz (THz) light pulses can be used for an ultrafast coherent manipulation of the magnetization. Driving the magnetization at THz frequencies is currently the fastest way of writing magnetic information in ferromagnets. Using time-resolved resonant magnetic scattering, we gain new insights to the THz-driven coherent magnetization dynamics on nanometer length scales. We observe ultrafast demagnetization and coherent magnetization oscillations that are governed by a time-dependent damping. This damping is determined by the interplay of lattice heating and magnetic anisotropy reduction revealing an upper speed limit for THz-induced magnetization switching. We show that in the presence of nanometer-sized magnetic domains, the ultrafast magnetization oscillations are associated with a correlated beating of the domain walls. The overall domain structure thereby remains largely unaffected which highlights the applicability of THz-induced switching on the nanoscale.

The ability of pulsed nature of synchrotron radiation opens up the possibility of studying microsecond dynamics in complex materials via speckle-based techniques. Here, we present the study of measuring the dynamics of a colloidal system by combining single and multiple X-ray pulses of a storage ring. In addition, we apply speckle correlation techniques at various pulse patterns to collect correlation functions from nanoseconds to milliseconds. The obtained sample dynamics from all correlation techniques at different pulse patterns are in very good agreement with the expected dynamics of Brownian motions of silica nanoparticles in water. Our study will pave the way for future pulsed X-ray investigations at various synchrotron X-ray sources using individual X-ray pulse patterns.

Understanding the non-equilibrium structure formation of thin films is a fundamental challenge with important implications also for technical applications. The interplay between adsorption, desorption, and surface diffusion may result in the formation of nontrivial surface morphologies. X-ray photon correlation spectroscopy opens up new possibilities for understanding these processes. In this work, we perform in situ x-ray experiments in grazing incidence geometry to follow the growth of diindenoperylene thin films in real time, revealing details of the dynamics during molecular island formation. Comparison with simulations allows to extract dynamic and kinetic time scales. We observe time scales in the range of a few hundred seconds which occur mainly due to kinetics, i.e. island growth. Importantly, we can relate the observed heterogeneous behavior in dynamics to the number of open layers, revealing information about the change in the roughness, and the growth speed of each layer.

In Bragg coherent diffractive imaging, the precise location of the measured crystals in the interior of the sample is usually missing. Obtaining this information would help the study of the spatially dependent behavior of particles in the bulk of inhomogeneous samples, such as extra-thick battery cathodes. This work presents an approach to determine the 3D position of particles by precisely aligning them at the instrument axis of rotation. In the test experiment reported here, with a 60 µm-thick LiNi0.5Mn1.5O4 battery cathode, the particles were located with a precision of 20 µm in the out-of-plane direction, and the in-plane coordinates were determined with a precision of 1 µm.

We report on a Fourier transform holography study, employing hard X-ray energies at a 3rd generation storage ring. Nano-structures of various sizes and shapes have been measured in ultra small angle x-ray scattering configuration reaching a resolution in the holographic reconstructions of about 50 nm. Reliable holograms have been obtained with 6.9×10 6 incident photons. Our results provide an important step forward towards routine split-pulse Fourier transform holography measurements at FEL sources and 4th generation ultralow-emittance sources.

Three-dimensional photon correlation spectroscopy (3D PCS) is a well-known technique developed to suppress multiple scattering contributions in correlation functions, which are inevitably involved when an optical laser is employed to investigate dynamics in a turbid system. Here, we demonstrate a proof-of-principle study of 3D PCS in the hard X-ray regime. We employ an X-ray optical cross-correlator to measure the dynamics of silica colloidal nanoparticles dispersed in polypropylene glycol. The obtained cross correlation functions show very good agreement with auto-correlation measurements. This demonstration provides the foundation for X-ray speckle-based studies of very densely packed soft matter systems.

The availability of sub 100 fs short and highly intense free-electron laser (FEL) pulses allows for new insights in laser-induced ultrafast demagnetization (LID) of ferromagnetic thin films on nanometer length scales. We designed a pair of in-vacuum Helmholtz coils, providing pulsed magnetic fields up to µ 0 H z = ±45 mT, for time-resolved experiments at FEL sources in transmission geometry. We report on the implementation of the Helmholtz coils in an optical-pump–resonant-magnetic-scattering (tr-XRMS) experiment at the FEL FERMI (Elettra, Trieste) to study LID in different magnetic domain networks. We discuss the limitations for multi-shot measurements, that rely on the full reversibility of the demagnetization process in-between two pump–probe events, and emphasize the importance of reference–pump–probe schemes, especially in tr-XRMS experiments that employ external H z fields.

X-ray photon correlation spectroscopy (XPCS) is a routine technique to study slow dynamics in complex systems at storage-ring sources. Achieving nanosecond time resolution with the conventional XPCS technique is, however, still an experimentally challenging task requiring fast detectors and sufficient photon flux. Here, the result of a nanosecond XPCS study of fast colloidal dynamics is shown by employing an adaptive gain integrating pixel detector (AGIPD) operated at frame rates of the intrinsic pulse structure of the storage ring. Correlation functions from single-pulse speckle patterns with the shortest correlation time of 192 ns have been calculated. These studies provide an important step towards routine fast XPCS studies at storage rings.

The ability to deliver two coherent X-ray pulses with precise time-delays ranging from a few femtoseconds to nanoseconds enables critical capabilities of probing ultra-fast phenomena in condensed matter systems at X-ray free electron laser (FEL) sources. Recent progress made in the hard X-ray split-and-delay optics developments now brings a very promising prospect for resolving atomic-scale motions that were not accessible by previous time-resolved techniques. Here, we report on characterizing the spatial and temporal coherence properties of the hard X-ray FEL beam after propagating through split-and-delay optics. Speckle contrast analysis of small-angle scattering measurements from nanoparticles reveals well-preserved transverse coherence of the beam. Measuring intensity fluctuations from successive X-ray pulses also reveals that only single or double temporal modes remain in the transmitted beam, corresponding to nearly Fourier transform limited pulses.

We present a novel experimental setup for performing a precise pre-alignment of a hard X-ray split-and-delay unit based on low coherence light interferometry and high-precision penta-prisms. A split-and-delay unit is a sophisticated perfect crystal-optics device that splits an incoming X-ray pulse into two sub-pulses and generates a controlled time-delay between them. While the availability of a split-and-delay system will make ultrafast time-correlation and X-ray pump-probe experiments possible at free-electron lasers, its alignment process can be very tedious and time-consuming due to its complex construction. By implementing our experimental setup at beamline P10 of PETRA III, we were able to reduce the time of alignment to less than 3 h. We also propose an alternate method for finding the zero-time delay crossing without the use of X-rays or pulsed laser sources. The successful demonstration of this method brings prospect for operating the split-and-delay systems under alignment-time-critical environments such as X-ray free electron laser facilities.

Presented here is a compact hard X-ray split-and-delay line for studying ultrafast dynamics at free-electron laser sources. The device is capable of splitting a single X-ray pulse into two fractions with delay times from −5 to 815 ps and femtosecond resolution, operating continuously in a wide energy range between 7 and 16 keV.