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With the recent developments of modern synchrotron and X-ray Free Electron Laser (XFEL) light sources high speed and micrometer sized liquid jets have become one of the most important sample delivery systems. For that reason it is highly important to develop liquid jet devices compatible with micrometer X-ray beams, which are optimized for the investigation of nanostructures and the behavior of complex liquids behavior under flow.This thesis reports a detailed X-ray scattering study of a liquid jet produced by a gas dynamic virtual nozzle (GDVN) system. [...]

A comprehensive collection of results on longitudinal double-spin asymmetries is presented for charged pions and kaons produced in semi-inclusive deep-inelastic scattering of electrons and positrons on the proton and deuteron, based on the full HERMES data set. The dependence of the asymmetries on hadron transverse momentum and azimuthal angle extends the sensitivity to the flavor structure of the nucleon beyond the distribution functions accessible in the collinear framework. [...]

The major challenge of Research in bone surgery is to develop strategies to repair large bone defects. Bone grafting technique is the gold standard to fill and heal these kind of defects. [...]

In a joint experimental and theoretical endeavor, photoionization of metastable $C^{4+}$($1s\,2s\; ^3S_ 1)$ ions via intermediate levels with hollow, double-K-vacancy configurations $2s2p, 2s3p, 2p3s, 2p3d, 2s4p, 2p4s$, and $2p4d$ has been investigated. High-resolution photon-ion merged-beams measurements were carried out with the resolving power reaching up to 25 800 which is sufficient to separate the leading fine-structure components of the $2s2p^{3}P$ term. [...]

We provide experimental and theoretical evidence for a pressure-induced Mott insulator-metal transition in $Fe_{2}O_3$ characterized by site-selective delocalization of the electrons. Density functional plus dynamical mean-field theory ($DFT+DMFT$) calculations, along with Mössbauer spectroscopy, x-ray diffraction, and electrical transport measurements on $Fe_{2}O_3$ up to 100 GPa, reveal this site-selective Mott transition between 50 and 68 GPa, such that the metallization can be described by $(^{VI}Fe^{3+HS})_{2}O_{3} [R\bar{3}c$  structure]$\begin{matrix}\longrightarrow \\ 50 GPa \end{matrix} (^{VIII}Fe^{3+HS} ^{VI}Fe^{M})O_3$ $[P21/n$  structure] $\begin{matrix}\longrightarrow \\ 68 GPa \end{matrix}(^{VI}Fe^{M})_{2}O_{3}[Aba2/PPv$  structure]. [...]

We report a systematic lattice dynamics study of the technologically important Fe$_3$Si/GaAs heterostructure for Fe$_3$Si layer thicknesses of 3, 6, 8, and 36 monolayers. The Fe-partial phonon density of states obtained by nuclear inelastic scattering exhibits up to a twofold enhancement of the low-energy phonon states compared to the bulk material for layer thicknesses of 8 monolayers and below. [...]

In this study, we report on the visco-elastic response during start-up and cessation ofshear of a novel bio-based liquid crystal polymer. The ensuing morphological changes are analyzedat different length scales by in-situ polarized optical microscopy and wide-angle X-ray diffraction.Upon inception of shear, the polydomain texture is initially stretched, at larger strain break upprocesses become increasingly important, and eventually a steady state texture is obtained. [...]

At present 26 RF stations for European XFEL are inoperation. Each RF station consists of a HV modulatorlocated in a separate building on the DESY campus, up to1600 m long 10 kV HV cables that connect the modulatorand the HV pulse transformer located in the undergroundtunnel, 120kV, 3 m long HV cable connecting the HVpulse transformer and the connection module (CM) of thehorizontal multi-beam klystron (MBK). [...]

An accurate description of the interaction of intense hard X-ray pulses with heavy atoms,which is crucial for many applications of free-electron lasers, represents a hitherto unresolvedchallenge for theory because of the enormous number of electronic configurations andrelativistic effects, which need to be taken into account. Here we report results on multipleionization of xenon atoms by ultra-intense (about 1019W/cm2) femtosecond X-ray pulses atphoton energies from 5.5 to 8.3 keV and present a theoretical model capable of reproducingthe experimental data in the entire energy range. [...]

The European XFEL uses 100 accelerating cryomodules. One RF station with 10 MW klystron supplies, through a waveguide distribution, four cryomodules with eight cavities each. [...]