Quantification routines for full 3D elemental distributions of homogeneous and layered samples obtained with laboratory confocal micro XRF spectrometers

Confocal micro X ray fluorescence spectroscopy can be performed with laboratory spectrometers for elemental imaging with 3D resolution. Due to self absorption inside a specimen and energy effects induced by the used polycapillary optics, interpretation of data can be challenging. Thus, quantification techniques to reconstruct sample composition and geometry are mandatory to widen the applicability of the technique to further fields of analytical chemistry. We present an analytical routine which facilitates the quantitative investigation of 3D data sets obtained with laboratory spectrometers. By fully calibrating the spectrometer parameters the procedure is generalized to be suitable for all spectrometers with known excitation spectra and polycapillary optics. Calibration and validation measurements on homogeneous and stratified samples are presented with a discussion on uncertainties and challenges. Finally, the localization of a goethite needle in a quartz matrix is presented as an example of a possible routine applicatio

Grazing incidence x ray fluorescence analysis for non destructive determination of In and Ga depth profiles in Cu In,Ga Se2 absorber films

Development of highly efficient thin film solar cells involves band gap engineering by tuning their elemental composition with depth. Here we show that grazing incidence X ray fluorescence GIXRF analysis using monochromatic synchrotron radiation and well characterized instrumentation is suitable for a non destructive and reference free analysis of compositional depth profiles in thin films. Variation of the incidence angle provides quantitative access to the in depth distribution of the elements, which are retrieved from measured fluorescence intensities by modeling parameterized gradients and fitting calculated to measured fluorescence intensities. Our results show that double Ga gradients in Cu In1 x,Gax Se2 can be resolved by GIXR

HESEB The Helmholtz state of the art Soft X Ray Undulator beamline at SESAME

SESAME and a consortium of five Helmholtz Centers are designing and installing a state of the art soft X Ray undulator beamline at the SESAME light source in Amman, Jordan. Funding is provided by the Helmholtz Association over a four year project cycle that started in January 2019. This is an interim report covering the first 36 months of the project where the construction and installation has been almost completed and commissioning and characterization of the beamline is about to start. Additionally, seminars, workshops, and a training program are part of the project aimed at establishing a broad user communit

Chemical speciation at buried interfaces in high temperature processed polycrystalline silicon thin film solar cells on ZnO Al

The combination of polycrystalline silicon poly Si thin films with aluminum doped zinc oxide layers ZnO Al as transparent conductive oxide enables the design of appealing optoelectronic devices at low costs, namely in the field of photovoltaics. The fabrication of both thin film materials requires high temperature treatments which are highly desired for obtaining a high electrical material quality. Annealing procedures are typically applied during crystallization and defect healing processes for silicon and can boost the carrier mobility and conductivity of ZnO Al layers. In a combined poly Si ZnO Al layer system an in depth knowledge of the interaction of both layers and the control of interface reactions upon thermal treatments is crucial. Therefore, we analyze the influence of rapid thermal treatments up to 1050 C on solid phase crystallized poly Si thin film solar cells on ZnO Al coated glass, focusing on chemical interface reactions and modifications of the poly Si absorber material quality. The presence of a ZnO Al layer in the solar cell stack was found to limit the poly Si solar cell performance with open circuit voltages only below 390 mV compared to 435 mV without ZnO film , even if a silicon nitride SiN diffusion barrier was included. A considerable amount of diffused zinc inside the silicon was observed. By grazing incidence x ray fluorescence spectrometry a depth resolving analysis of the elemental composition close to the poly Si SiN ZnO Al interface was carried out. Temperatures above 1000 C were found to promote the formation of new chemical compounds within about 10 nm of interface, such as zinc silicates Zn2SiO4 and aluminium oxide AlxOy . These results give valuable insights about the temperature limitations of Si ZnO thin film solar cell fabrication and the formation of high mobility ZnO layers by thermal annea

Preparation of Reinforced Anisometric Patchy Supraparticles for Self Propulsion

The preparation of fumed silica based anisometric supraparticles with well defined catalytically active patches suitable for self propulsion is presented here. These sub millimeter sized particles can self propel as they contain Pt covered magnetite Fe3O4 nanoparticles, where the Pt can decompose catalytically a fuel like H2O2 and thereby propel the supraparticles. By their magnetic properties, the catalytically active nanoparticles can be concentrated in patches on the supraparticle surface. The goal is to obtain robust supraparticles with well defined patchiness and long time stability during self propulsion through evaporation induced self assembly EISA on a superhydrophobic surface. The latter is a major issue as oxygen evolution can lead to the disintegration of the supraparticles. Therefore, enhanced mechanical stability is sought using a number of different additives, where the best results are obtained by incorporating polystyrene microspheres followed by heat treatment or reinforcement with microfibrillated cellulose MFC and sodium trisilicate Na2SiO3 . The detailed internal structure of the different types of particles is investigated by confocal micro X ray fluorescence spectroscopy CMXRF , which allows for precisely locating the catalytic Fe3O4 Pt nanoparticles within the supraparticles with a resolution in the m range. The insights on the supraparticle structure, together with their long time stability, allow fabricating optimized patchy supraparticles for potential applications in propulsion enhanced catalysi