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Recent research on hydrogen storage in metal–organic frameworks focuses on how to achieve increased hydrogen binding energies by using doped metal, using unsaturated metal ions, or forming composites comprising Pt-doped carbon materials. In particular, noticeable progress using MOFs and Pt-doped carbons has been achieved to enhance the hydrogen storage capacity near room temperature. A three-component composite material, Pt-MWCNT-MOF5 (PMM5), which is a metal–organic framework (MOF-5) hybridized with Pt nanoparticles on multiwalled carbon nanotubes (MWCNT), stores 0.22 wt % hydrogen at 320 K and 30 bar, which is larger than 0.13 wt % at 300 K and 30 bar. Although the increased quantity is small, it is possible to detect the origin of uptake increase based on various analyses. In situ neutron diffraction experiments of deuterium-sorbed PMM5 with a temperature cycling process (D2 loading at 50 K → 4 K → 320 K, 2 h → 50 K → 4 K) result in a significant background increase owing to both chemisorbed deuterium atoms and a local deformation of the MOF-5 framework. Hydrogen loading in PMM5 induces significant binding energy shifts in C 1s and Zn 2p3/2 electrons in the X-ray photoelectron spectra, suggesting the chemical environment change in Zn4O(COO)6 coordination sphere in MOF-5. All accumulated experimental data support the fact that the hydrogen receptor is the oxygen atoms of benzene-1,4-dicarboxylates of MOF-5, which is facilitated by the embedded Pt-MWCNT.

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The PERCIVAL detector is a CMOS imager designed for the soft X-ray regime at photon sources. Although still in its final development phase, it has recently seen its first user experiments: ptychography at a free-electron laser, holographic imaging at a storage ring and preliminary tests on X-ray photon correlation spectroscopy. The detector performed remarkably well in terms of spatial resolution achievable in the sample plane, owing to its small pixel size, large active area and very large dynamic range; but also in terms of its frame rate, which is significantly faster than traditional CCDs. In particular, it is the combination of these features which makes PERCIVAL an attractive option for soft X-ray science.

In this work, single-shot ptychography was adapted to the XUV range and, as a proof of concept, performed at the free-electron laser FLASH at DESY to obtain a high-resolution reconstruction of a test sample. Ptychography is a coherent diffraction imaging technique capable of imaging extended samples with diffraction-limited resolution. However, its scanning nature makes ptychography time-consuming and also prevents its application for mapping of dynamical processes. Single-shot ptychography can be realized by collecting the diffraction patterns of multiple overlapping beams in one shot and, in recent years, several concepts based on two con-focal lenses were employed in the visible regime. Unfortunately, this approach cannot be extended straightforwardly to X-ray wavelengths due to the use of refractive optics. Here, a novel single-shot ptychography setup utilizes a combination of X-ray focusing optics with a two-dimensional beam-splitting diffraction grating. It facilitates single-shot imaging of extended samples at X-ray wavelengths.

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Ptychograhy is a scanning coherent diffraction imaging technique capable of providing images of extended samples with diffraction-limited resolution. However, ptychography experiments are time-consuming due to their scanning nature which also prevents their use for imaging of dynamical processes. Recently, setups based on two con-focal lenses were proposed to perform single-shot ptychography in the visible regime by measuring the diffraction pattern produced by multiple overlapping beams in one shot. However, this approach cannot be extended straightforwardly to X-ray wavelengths due to the application of refractive optics. In this work, we demonstrate a novel and nascent single-shot ptychography setup utilizing the combination of X-ray focusing optics with a two-dimensional beam-splitting diffraction grating. It allows single-shot imaging of extended samples at X-ray wavelengths. As a proof of concept, we performed single-shot ptychography in the XUV range at the free-electron laser FLASH and obtained a high-resolution reconstruction of the sample.

Polyethylene terephthalate (PET) is a thermoplastic polyester with numerous applications in industry. However, it requires surface modification on an industrial scale for printing and coating processes and plasma treatment is one of the most commonly used techniques to increase the hydrophilicity of the PET films. Systematic improvement of the surface modification by adaption of the plasma process can be aided by a comprehensive understanding of the surface morphology and chemistry. However, imaging large surface areas (tens of microns) with a resolution that allows understanding the surface quality and modification is challenging. As a proof-of-principle, plasma-treated PET films were used to demonstrate the capabilities of X-ray ptychography, currently under development at the soft X-ray free-electron laser FLASH at DESY, for imaging macroscopic samples. In combination with scanning electron microscopy (SEM), this new technique was used to study the effects of different plasma treatment processes on PET plastic films. The studies on the surface morphology were complemented by investigations of the surface chemistry using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). While both imaging techniques consistently showed an increase in roughness and change in morphology of the PET films after plasma treatment, X-ray ptychography can provide additional information on the three-dimensional morphology of the surface. At the same time, the chemical analysis shows an increase in the oxygen content and polarity of the surface without significant damage to the polymer, which is important for printing and coating processes.