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This work reports laboratory angle resolved measurements with the goal of establishing laboratory techniques to obtain a more complete idea of the intralayer composition of multilayer samples. While X-ray reflectometry is a widely available technique for the characterization of multilayer samples, angle resolved XRF measurements (grazing emission/incidence X-ray fluorescence) are usually performed at synchrotron radiation facilities. With the development of efficient laboratory spectrometers and evaluation algorithms for angle resolved measurements, these methods become suited for routine measurements and screening. We present two laboratory spectrometers which make quantitative non-destructive elemental depth profiling feasible. For reasons of comparison a validation sample, a nickel–carbon multilayer sample, is measured with both setups and additional information on krypton contamination and its distribution is retrieved. Additionally, the first application for the characterization of multilayer structures with sub-nanometer layer thicknesses is shown.

Efficient soft X-ray spectroscopy in the laboratory is still a challenging task. Here, we report on new toroidal multilayer optics designed and applied with the laser-produced plasma (LPP) source of the Berlin Laboratory for innovative X-ray technologies. The optics are described and characterized, and the application of the updated source to scanning-free grazing emission X-ray fluorescence is demonstrated on thermoelectric gold-doped copper oxide nanofilms. The comparison with synchrotron measurements allows estimating a flux on the sample of approximately 7.5 × 109 photons/s in the 1 keV range on a 100 µm × 100 µm spot, emphasizing the suitability of the updated LPP source for the application in photon hungry experiments. K.B. is most grateful for the scholarship from the International Max-Planck Research School at the Fritz Haber Institute. J.B. would like to thank the Excellence Initiative of the Deutsche Forschungsgemeinschaft for financial support.

In principle, most X-ray sensitive pixelated detectors like CCDs or active pixel sensors (e.g. CMOS detectors) can be operated in single-photon counting (SPC) mode. In combination with rather simple data post-processing steps, this allows the exploitation of energy-dispersive properties similar to hybrid-pixel detectors and pnCCDs. For example, energy discrimination can be used to simultaneously measure the spatial distribution of various fluorescence lines on the detector chip or enable noise suppression in wavelength-dispersive measurements. Furthermore, due to the analysis of the charge distribution on the detector resulting from an absorbed X-ray photon, sub-pixel spatial resolution can be achieved. Where applicable, those additional features can be utilized without any hardware modification at the detector. There is a large potential for novel experiments and sensitivity gain in many laboratories already applying pixelated detectors, but only a few experiments indeed use this potential. The up until now published algorithms are hardly validated and rarely described in detail. Besides a thorough description of various algorithms for photon event evaluation, this work concentrates on a quantitative and qualitative comparison of such algorithms with respect to energy resolution, efficiency and photon recovery. For this purpose, the algorithms are tested on simulated data featuring various detector noise and charge-cloud size values and the influence of noise thresholds and photon density is discussed. Finally, we present two examples to demonstrate the advantages of photon event evaluation and highlight its benefits for X-ray spectroscopic applications.

An angle resolved X-ray fluorescence spectrometer based on the concept of scanning-free shallow detection with energy-dispersive area detectors is presented. The instrument is characterized with respect to energy resolution, linearity, angular discrimination and repeatability and the necessary data evaluation strategies are presented in detail. As demonstration of its capabilities and showcase for potential applications, two different copper indium gallium (di)selenide (CIGS) absorber layers, typically applied in thin film solar cells, are analyzed. In combination with quantitative (but integral) results for layer composition and layer thickness from a commercial XRF spectrometer, depth profiles of the Ga concentration of both ≈ 2 μm thin samples are obtained. The results of the novel spectrometer compare well with quantitative depth-profiles obtained from glow-discharge optical emission spectrometry. The combination of simplicity, stability and efficiency of the spectrometer concept makes it a potential candidate for industrial applications. Description of compact angle-resolved X-ray fluorescence spectrometer. Exploiting scanning-free grazing emission X-ray fluorescence approach. Energy dispersive charge-coupled device with single-photon detection. Enabling non-destructive, quantitative elemental depth profiling. Depth profiling of nano-structured stratified specimen, here CIGS solar cells.

Efficient multilayer optics for radiation in the water window range are difficult to manufacture due to extremely small layer thicknesses and severe intermixing of elements between the layers. Therefore, adequate analytics and short feedback loops are of utmost importance for manufacturers to improve performance and efficiency. We show the possibility for non-destructive elemental depth profiling with commercial laboratory equipment using four real-life CrSc multilayer samples. Comparative measurements at the laboratory of PTB at the synchrotron radiation facility BESSY II confirm the results and prove the potential of laboratory equipment for the reliable analysis of stratified materials with sub-nanometer layer thicknesses.

We present grazing incidence X-ray fluorescence (GIXRF) experiments on 3D periodically textured interfaces of liquid phase crystallized silicon thin-film solar cells on glass. The influence of functional layers (SiOx or SiOx/SiCx) – placed between glass substrate and silicon during crystallization – on the final carbon and oxygen contaminations inside the silicon was analyzed. Baring of the buried structured silicon surface prior to GIXRF measurement was achieved by removal of the original nano-imprinted glass substrate by wet-chemical etching. A broad angle of incidence distribution was determined for the X-ray radiation impinging on this textured surface. Optical simulations were performed in order to estimate the incident radiation intensity on the structured surface profile considering total reflection and attenuation effects. The results indicate a much lower contamination level for SiOx compared to the SiOx/SiCx interlayers, and about 25% increased contamination when comparing structured with planar silicon layers, both correlating with the corresponding solar cell performances.

A flexible spectrograph for the investigation of soft X-ray spectra in the range between 1 nm and 20 nm is presented. Based on two variable-line spaced reflection gratings, the design enables stand-alone operation, the change between the use of an entrance slit and a slitless operation mode as well as a maximum compactness and robustness due to a reduced number of motorized stages. Characterization measurements as well as first proof-of-principle X-ray emission investigations show the potential of the instrument for versatile applications.A flexible spectrograph for the investigation of soft X-ray spectra in the range between 1 nm and 20 nm is presented. Based on two variable-line spaced reflection gratings, the design enables stand-alone operation, the change between the use of an entrance slit and a slitless operation mode as well as a maximum compactness and robustness due to a reduced number of motorized stages. Characterization measurements as well as first proof-of-principle X-ray emission investigations show the potential of the instrument for versatile applications.

In the water window (2.2 – 4.4 nm) the attenuation of radiation in water is significantly smaller than in organic material. Therefore, intact biological specimen (e.g. cells) can be investigated in their natural environment. In order to make this technique accessible to users in a laboratory environment a Full-Field Laboratory Transmission X-ray Microscope (L-TXM) has been developed. The L-TXM is operated with a nitrogen laser plasma source employing an InnoSlab high power laser system for plasma generation. For microscopy the Lyα emission of highly ionized nitrogen at 2.48 nm is used. A laser plasma brightness of 5 × 1011 photons/(s × sr × μm2 in line at 2.48 nm) at a laser power of 70 W is demonstrated. In combination with a state-of-the-art Cr/V multilayer condenser mirror the sample is illuminated with 106 photons/(μm2 × s). Using objective zone plates 35 – 40 nm lines can be resolved with exposure times < 60 s. The exposure time can be further reduced to 20 s by the use of new multilayer condenser optics and operating the laser at its full power of 130 W. These exposure times enable cryo tomography in a laboratory environment.

X-ray microscopy in the water window has become a valuable imaging tool for a wide field of applications with a resolution in the nanometer regime. The emergence and the development of laboratory based transmission X-ray microscopes (LTXM) can be of great benefit to users, since LTXM provides access to a method previously limited to synchrotron facilities only. In recent years, measuring times in the laboratory have been reduced to the point, where tomography of aqueous cryofixated samples has become feasible. We report on a laboratory full-field transmission X-ray microscope based on a laser induced plasma source located at the Berlin Laboratory for innovative X-ray Technologies. A short introduction on full-field X-ray microscopy in the water window is given. We demonstrate that, with a thin disk laser-system (TDL), which provides an average power of ~15 W a spatial resolution of Δx = 41 nm ± 3 nm (half-pitch) is feasible. An image of a diatom recorded at 15 W average laser power with a magnification of 1125x captured in 5 min is presented.