A5061958462- X-ray Spectroscopy and Fluorescence Analysis
- Electron and X-Ray Spectroscopy Techniques
- Ion-surface interactions and analysis
- Advanced X-ray Imaging Techniques
- Atomic and Molecular Physics
- Nuclear Physics and Applications
- X-ray Diffraction in Crystallography
- Crystallography and Radiation Phenomena
- Advanced Electron Microscopy Techniques and Applications
- Advanced X-ray and CT Imaging
- Diamond and Carbon-based Materials Research
- High-pressure geophysics and materials
- Advanced Chemical Physics Studies
- Laser-Plasma Interactions and Diagnostics
- Advanced Surface Polishing Techniques
- 2D Materials and Applications
- Radioactive element chemistry and processing
- Molecular Junctions and Nanostructures
- Analytical chemistry methods development
- Food composition and properties
- Integrated Circuits and Semiconductor Failure Analysis
- Laser-induced spectroscopy and plasma
- Particle Accelerators and Free-Electron Lasers
- Semiconductor materials and interfaces
- Mass Spectrometry Techniques and Applications
University of Fribourg
2014-2024
Fribourg Development Agency
2015
Jan Kochanowski University
2011
European Synchrotron Radiation Facility
2000-2009
European Science Foundation
2004-2008
Nicolaus Copernicus University
2001
Jožef Stefan Institute
2000
National Centre for Nuclear Research
1992
We report on the design and performance of a wavelength-dispersive type spectrometer based von Hamos geometry. The is equipped with segmented-type crystal for x-ray diffraction provides an energy resolution in order 0.25 eV 1 over range 8000 eV–9600 eV. use segmented results simple straightforward preparation that allows to preserve efficiency. Application time-resolved resonant inelastic scattering single-shot emission spectroscopy demonstrated.
For several years the ESRF, University of Witwatersrand and De Beers Industrial Diamonds (PTY) Ltd through their Diamond Research Laboratories have pursued a development programme to improve quality synthetic diamond crystals. Recently, in an effort study influence nitrogen impurities on defect structure, x-ray excited optical luminescence spatially resolved double-crystal diffractometry were employed as new techniques. Finally, impurity concentration distribution obtained by spectroscopy...
The trend in synchrotron radiation (x-rays) is towards higher brilliance. This may lead to a very high power density, of the order hundreds watts per square millimetre at x-ray optical elements. These elements are, typically, windows, polarizers, filters and monochromators. preferred material for Bragg diffracting present silicon, which can be grown crystal perfection workable size as well rather easily processed required surface quality. allows built with sufficient degree lattice...
The fabrication and testing of planar refractive hard X-ray lenses made from bulk CVD diamond substrates is reported. lens structures were generated by electron-beam lithography transferred reactive-ion etching into the diamond. Various designs fabricated tested at 12.4 17.5 keV photon energy. Efficiencies up to 71% gains 26 achieved. A line focus 3.2 micro m (FWHM) was measured. These should be able withstand extreme flux densities expected planned fourth-generation sources.
We report on the photon energy dependence of K-shell double photoionization (DPI) Mg, Al, and Si. The DPI cross sections were derived from high-resolution measurements x-ray spectra following radiative decay vacancy states. Our data evince relative importance final-state electron-electron interaction to DPI. By comparing double-to-single cross-section ratios for neutral atoms with convergent close-coupling calculations He-like ions, effect outer shell electrons process is assessed. Universal...
The development of a wavelength-dispersive spectrometer for microfluorescence analysis at the X-ray Microscopy ID21 beamline European Synchrotron Radiation Facility (ESRF) is reported. based on polycapillary optic fluorescence collection and operated in flat-crystal geometry. design considerations as well operation characteristics are presented. achieved performances, particular energy resolution, compared with results Monte Carlo simulations. Further improvement down to approximately eV...
Abstract X-ray techniques have evolved over decades to become highly refined tools for a broad range of investigations. Importantly, these approaches rely on measurements that depend linearly the number incident photons. The advent free electron lasers (XFELs) is opening ability reach extremely high photon numbers within ultrashort pulse durations and leading paradigm shift in our explore nonlinear signals. However, enormous increase peak power double-edged sword with new exciting methods...
We report on the decomposition of platinum acetylacetonate (Pt(acac)2) in hydrogen induced by flash heating. The changes local Pt structure were followed high energy resolution off-resonant spectroscopy uniquely performed with sub-second time resolution. consists a two-step reduction process Pt(II) species.
X-ray emission spectra recorded in the off-resonant regime carry information on density of unoccupied states. It is known that by employing Kramers-Heisenberg formalism, high energy resolution spectroscopy (HEROS) equivalent to x-ray absorption (XAS) technique and provides same electronic state information. Moreover, present Letter we demonstrate shape HEROS not modified self-absorption effects. Therefore, contrast fluorescence-based XAS techniques, independent sample concentration or...
Abstract A critical factor for electronics based on inorganic layered crystals stems from the electrical contact mode between semiconducting and metal counterparts in electric circuit. Here, a materials tailoring strategy via nanocomposite decoration is carried out to reach metallic MoS 2 matrix transition nanoparticles. Nickel nanoparticles (NiNPs) are successfully joined sides of crystal through gold nanobuffers, forming magnetic NiNPs@MoS complexes. The intrinsic property remains...
X-ray atomic properties of nickel were investigated in a singular approach that combines different experimental techniques to obtain new and useful reliable values fundamental parameters for spectrometric purposes comparison theoretical predictions.We determined the mass attenuation coefficients an energy range covering L-and K-absorption edges, K-shell fluorescence yield Kβ/Kα Kβ 1,3/K α1,2 transition probability ratios.The obtained line profiles linewidths Kα transitions Ni can be...
Physical, biological, and chemical transformations are initiated by changes in the electronic configuration of species involved. These occur on timescales attoseconds (10−18 s) to femtoseconds (10−15 drive all subsequent reorganization as system moves a new equilibrium or quasi-equilibrium state. The ability detect dynamics these is crucial for understanding potential energy surfaces upon which biological reactions take place. Here, we report determination structure matter using single...
In this work two synchrotron radiation-based depth-sensitive X-ray fluorescence techniques, grazing incidence (GIXRF) and emission (GEXRF), are compared their potential for non-destructive depth-profiling applications is investigated. The capabilities of the methods illustrated five aluminum-implanted silicon wafers all having same implantation dose 1016 atoms per cm2 but with different energies ranging from 1 keV up to 50 keV. was motivated by ongoing downscaling effort microelectronics...
Chemical reactions are always associated with electronic structure changes of the involved chemical species. Determining configuration an atom allows probing its state and gives understanding reaction pathways. However, often too complex fast to be measured at in situ conditions due slow and/or insensitive experimental techniques. A short-lived Au2O compound has been detected for first time under during temperature-programmed reduction Au2O3. time-resolved resonant inelastic X-ray scattering...
The K\ensuremath{\alpha} and K\ensuremath{\beta} x-ray spectra of molybdenum bombarded by 5.5-MeV/amu $^{16}\mathrm{O}$ ions were measured with high resolution. In such heavy-ion--atom collisions, multiple ionization the M L shells target atoms is extremely likely to occur, resulting in a complex structure observed spectra. ${\mathit{L}}^{\mathit{n}}$-satellite was resolved, whereas vacancies produce only shift broadening lines so that it not possible obtain direct way information about...
We present measurements of the resonant inelastic x-ray scattering (RIXS) spectra CH3I molecule in hard-x-ray region near iodine L2 and L3 absorption edges. show that dispersive RIXS spectral features were recognized as a fingerprint dissociative molecular states can be interpreted terms ultrashort natural lifetime ∼200 attoseconds case L-shell core-hole. Our results demonstrate capacity technique to reveal subtle dynamical effects molecules with sensitivity nuclear rearrangement on...
Experimental evidence for the correlated two-electron one-photon transitions (1s(-2)→2s(-1)2p(-1)) following single-photon K-shell double ionization is reported. The vacancy states in solid Mg, Al, and Si were produced by means of monochromatized synchrotron radiation, radiative observed using a wavelength dispersive spectrometer. transition energies branching ratios one-electron to determined compared available perturbation theory predictions configuration interaction calculations.
The high-resolution von Hamos bent crystal spectrometer of the University Fribourg was upgraded with a focused X-ray beam source aim performing micro-sized fluorescence (XRF) measurements in laboratory. integrates collimating optics mounted on low-power micro-spot tube and focusing polycapillary half-lens placed front sample. performances setup were probed terms spatial energy resolution. In particular, intensity resolution equipped novel micro-focused standard high-power water-cooled...
We report on a high-resolution transmission-type curved crystal spectrometer based the modified DuMond slit geometry. The was developed at University of Fribourg for study photoinduced X-ray spectra. K and L transitions with energies above about 10 keV can be measured an instrumental resolution comparable to their natural linewidths. Construction details operational characteristics are presented. variation energy as function focal distance diffraction order is discussed. high sensitivity...
We report on the application of synchrotron radiation based high-resolution grazing-emission x-ray fluorescence (GEXRF) method to measure low-level impurities silicon wafers. The presented GEXRF technique leads direct detection limits about 1012 atoms/cm2. latter can be presumably further improved down 107 atoms/cm2 by combining radiation-based with vapor phase decomposition preconcentration technique. capability perform surface-sensitive elemental mappings a lateral resolution several tens...
We propose a novel approach for the theoretical analysis of photoinduced high-resolution K(h)α(1,2) x-ray hypersatellite spectra, which allows us to obtain reliable values lifetimes doubly K-shell ionized states and fundamental information about relative role double photoionization (DPI) mechanisms. It is demonstrated first time that natural line broadening observed selected metal atoms with 20 ≤ Z 30 can be well reproduced quantitatively by taking into account influences open-shell valence...
Fluorescence yields (FYs) for the Ge $L$ shell were determined by a theoretical and two experimental groups within framework of International Initiative on X-Ray Fundamental Parameters Collaboration. Calculations performed using Dirac-Fock method, including relativistic QED corrections. The value ${L}_{3}\phantom{\rule{0.28em}{0ex}}\mathrm{FY}\phantom{\rule{0.28em}{0ex}}{\ensuremath{\omega}}_{{L}_{3}}$ was at Physikalisch-Technische Bundesanstalt undulator beamline synchrotron radiation...