The double K-shell ionization of Sc, Cr and Cu induced by electron impact was investigated via high energy resolution measurements of the K alpha diagram transitions and the transitions resulting from the radiative decay of K-shell double vacancy states, namely the K-h alpha hypersatellites. For Sc, the K beta diagram lines and K-h beta hypersatellites were also measured. The measurements were carried out in-house with a von Hamos curved crystal spectrometer operated in the so-called direct geometry in which the anodes of Sc, Cr and Cu X-ray tubes were used as targets. For each element, the electron kinetic energy was chosen to be about twice the threshold energy for the double 1s ionization. The double-to-single ionization cross-sections ratios P-KK were deduced from the hypersatellite-to-diagram line yield ratios, corrected beforehand for the self-absorption of the X-rays in the target and the energy dependent efficiency of the spectrometer. The obtained ratios are discussed and compared to other P-KK values found in the literature for electrons and photons.

We report on a laboratory-based facility for in-house x-ray absorption fine structure (XAFS) measurements. The device consists of a conventional x-ray source for the production of the incident polychromatic radiation and a von Hamos bent crystal spectrometer for the analysis of the incoming and transmitted radiation. The reliability of the laboratory-based setup was evaluated by comparing the Cu K-edge and Ta L3-edge XAFS spectra obtained in-house with the corresponding spectra measured at a synchrotron radiation facility. To check the accuracy of the device, the K- and L-edge energies and the attenuation coefficients below and above the edges of several 3d, 4d, and 5d elements were determined and compared with the existing experimental and theoretical data. The dependence of the XAFS spectrum shape on the oxidation state of the sample was also probed by measuring inhouse the absorption spectra of metallic Fe and two Fe oxides (Fe2O3 and Fe3O4).

emission studies in the energy range of 15 to 26 keV P. Jagodzi«ski, 2, a) J. Szlachetko, J.-Cl. Dousse, J. Hoszowska, M. Szlachetko, U. Vogelsang, D. Bana±, T. Pakendorf, A. Meents, J.A. van Bokhoven, A. Kubala-Kuku±, M. Pajek, and M. Nachtegaal b) 1)Swiss Light Source, Paul Scherrer Institute (PSI), CH-5232 Villigen, Switzerland 2)Department of Mathematics and Physics, Kielce University of Technology, PL-25-314 Kielce, Poland 3)Institute of Nuclear Physics Polish Academy of Science, PL-31-342 Kraków, Poland 4)Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland 5)Institute of Physics, Jan Kochanowski University, PL-25-406 Kielce, Poland 6)PETRA, Deutsches Elektronen-Synchrotron (DESY), DE-22607 Hamburg, Germany

The design and performance of a high-resolution transmission-type X-ray spectrometer for use in the 15-26 keV energy range at synchrotron light sources is reported. Monte Carlo X-ray-tracing simulations were performed to optimize the performance of the transmission-type spectrometer, based on the DuMond geometry, for use at the Super X-ray absorption beamline of the Swiss Light Source at the Paul Scherrer Institute. This spectrometer provides an instrumental energy resolution of 3.5 eV for X-ray emission lines around 16 keV and 12.5 eV for emission lines at 26 keV, which is comparable to the natural linewidths of the K and L X-ray transitions in the covered energy range. First experimental data are presented and compared with results of the Monte Carlo X-ray simulations.

We report on the radiative decay of double K-shell vacancy states produced in solid Ca, V, Fe, and Cu targets by impact with about 10 MeV/amu C and Ne ions. The resulting K hypersatellite x-ray emission spectra were measured by means of high-energy-resolution spectroscopy using a von Hamos bent crystal spectrometer. The experiment was carried out at the Philips variable energy cyclotron of the Paul Scherrer Institute. From the fits of the x-ray spectra the energies, line widths, and relative intensities of the hypersatellite x-ray lines could be determined. The fitted intensities were corrected to account for the energy-dependent solid angle of the spectrometer, effective source size, target self-absorption, crystal reflectivity, and detector efficiency. The single-to-double K -shell ionization cross-section ratios were deduced from the corrected relative intensities of the hypersatellites and compared to theoretical predictions from the semiclassical approximation model using hydrogenlike and Dirac-Hartree-Fock wave functions and from classical trajectory Monte Carlo calculations.

The x-ray atomic properties of nickel (Ni) were investigated in a unique approach combining different experimental techniques to obtain new, useful and reliable values of atomic fundamental parameters for x-ray spectrometric purposes and for comparison with theoretical predictions. We determined the mass attenuation coefficients in an energy range covering the L-and K-absorption edges, the K-shell fluorescence yield and the K beta / K alpha and K beta 1,3/K alpha 1,2 transition probability ratios. The obtained line profiles and linewidths of the K alpha and K beta transitions in Ni can be considered as the contribution of the satellite lines arising from the [KM] shake processes suggested by Deutsch et al (1995 Phys. Rev. A 51 283) and Ito et al (2016 Phys. Rev. A 94 042506). Comparison of the new data with several databases showed good agreement, but also discrepancies were found with existing tabulated values.

The potential of valence to core Al X-ray emission spectroscopy to determine aluminum distribution in ferrierite zeolites was investigated. The recorded emission spectra of four samples prepared with different structure directing agents exhibit slight variations in the position of the main emission peak and the intensity of its low energy shoulder. Theoretical calculations indicate that an increased intensity of the Kβx shoulder in the Al emission spectra can be linked to a predominant occupation of the T3 site by a single aluminum atom. This study thus suggests that valence to core X-ray emission spectroscopy can be applied to help determine the occupation of aluminum at crystallographic T-sites in zeolites.

High energy resolution off-resonant X-ray emission spectroscopy (HEROS) was applied to study one-photon (OPA) and two-photon absorption (TPA) processes in metallic copper generated by ultra-short hard X-ray FEL pulses from the Linac Coherent Light Source (LCLS). The OPA and TPA signals were measured using a multiple-crystal von Hamos diffraction spectrometer allowing observation of both the intermediate and final states in the TPA process. The universal scaling of TPA/OPA cross sections is discussed.

Fluorescence yields (FYs) for the Ge L shell were determined by a theoretical and two experimental groups within the framework of the International Initiative on X-Ray Fundamental Parameters Collaboration. Calculations were performed using the Dirac-Fock method, including relativistic and QED corrections. The experimental value of the L-3 FY omega(L3) was determined at the Physikalisch-Technische Bundesanstalt undulator beamline of the synchrotron radiation facility BESSY II in Berlin, Germany, and the L alpha(1,2) and L beta(1) line widths were measured at the Swiss Light Source, Paul Scherrer Institute, Switzerland, using monochromatized synchrotron radiation and a von Hamos x-ray crystal spectrometer. The measured fluorescence yields and line widths are compared to the corresponding calculated values.

We report on nonlinear interaction of solid Fe with intense femtosecond hard x-ray free-electron laser (XFEL) pulses. The experiment was performed at the CXI end-station of the Linac Coherent Light Source (LCLS) by means of high- resolution x-ray emission spectroscopy. The focused x-ray beam provided extreme fluence of ∼105 photons/Å2. Two-photon absorption leading to K-shell hollow atom formation and to single K-shell ionization of solid Fe was investigated.

We report on high energy resolution measurements of the Kα hypersatellite x-ray spectra of Ca, V, Fe and Cu induced by impact with 144 MeV C and 180 MeV Ne ions.

We report on vacuum ultraviolet (VUV) excited photoluminescence (PL) spectra emitted from a chemical vapor deposited MoS2 few-layered film. The excitation spectrum was recorded by monitoring intensities of PL spectra at ~1.9 eV. A strong wide excitation band peaking at 7 eV was found in the excitation. The PL excitation band is most intensive at liquid helium temperature and completely quenched at 100 K. Through first-principles calculations of photoabsorption in MoS2, the excitation was explicated and attributed to transitions of electrons from p- and d- type states in the valence band to the d- and p-type states in the conduction band. The obtained photon-in/photon-out results clarify the excitation and emission behavior of the low dimensional MoS2 when interacting with the VUV light sources.

D. Banaś,1 M. Pajek,1 A. Surzhykov,2 Th. Stöhlker,2,3,4 C. Brandau,3,5 A. Gumberidze,6 C. Kozhuharov,3 H. F. Beyer,3 S. Böhm,5 F. Bosch,3 M. Czarnota,1 S. Chatterjee,3,* J.-Cl. Dousse,7 S. Fritzsche,2,8 S. Hagmann,3 D. Liesen,3 P. H. Mokler,3 A. Müller,5 A. Kumar,3 R. Reuschl,3 D. Sierpowski,9 U. Spillmann,3 J. Szlachetko,1,7 S. Tashenov,2,10 S. Trotsenko,2,3 P. Verma,3 and A. Warczak9 1Institute of Physics, Jan Kochanowski University, PL-25-406 Kielce, Poland 2Helmholtz-Institut Jena, D-07743 Jena, Germany 3GSI Helmholtzzentrum für Schwerionenforschung, D-64291 Darmstadt, Germany 4Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität Jena, D-07743 Jena, Germany 5Institut für Atom und Molekülphysik, Justus-Liebig-Universität, D-35392 Giessen, Germany 6ExtreMe Matter Institute EMMI and Research Division, GSI Helmholtzzentrum für Schwerionenforschung, D-64291 Darmstadt, Germany 7Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland 8Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universität Jena, D-07743 Jena, Germany 9Institute of Physics, Jagiellonian University, PL-30-059 Cracow, Poland 10Physikalisches Institut der Universität Heidelberg, D-69120 Heidelberg, Germany (Received 13 July 2015; published 21 September 2015)

The high-resolution von Hamos bent crystal spectrometer of the University of Fribourg was upgraded with a focused X-ray beam source with the aim of performing micro-sized X-ray fluorescence (XRF) measurements in the laboratory. The focused X-ray beam source integrates a collimating optics mounted on a low-power micro-spot X-ray tube and a focusing polycapillary half-lens placed in front of the sample. The performances of the setup were probed in terms of spatial and energy resolution. In particular, the fluorescence intensity and energy resolution of the von Hamos spectrometer equipped with the novel micro-focused X-ray source and a standard high-power water-cooled X-ray tube were compared. The XRF analysis capability of the new setup was assessed by measuring the dopant distribution within the core of Er-doped SiO2 optical fibers.

Various 3-dimensional nano-scaled periodic structures with different configurations and periods deposited on the surface of silicon and silica substrates were investigated by means of the grazing incidence and grazing emission X-ray fluorescence techniques. Apart from the characteristics which are typical for particle- and layer-like samples, the measured angular intensity profiles show additional periodicity-related features. The latter could be explained by a novel theoretical approach based on simple geometrical optics (GO) considerations. The new GO-based calculations were found to yield results in good agreement with experiment, also in cases where other theoretical approaches are not valid, e.g., periodic particle distributions with an increased surface coverage.

Physical, biological, and chemical transformations are initiated by changes in the electronic configuration of the species involved. These electronic changes occur on the timescales of attoseconds (10−18 s) to femtoseconds (10−15 s) and drive all subsequent electronic reorganization as the system moves to a new equilibrium or quasi-equilibrium state. The ability to detect the dynamics of these electronic changes is crucial for understanding the potential energy surfaces upon which chemical and biological reactions take place. Here, we report on the determination of the electronic structure of matter using a single self-seeded femtosecond x-ray pulse from the Linac Coherent Light Source hard x-ray free electron laser. By measuring the high energy resolution off-resonant spectrum (HEROS), we were able to obtain information about the electronic density of states with a single femtosecond x-ray pulse. We show that the unoccupied electronic states of the scattering atom may be determined on a shot-to-shot basis and that the measured spectral shape is independent of the large intensity fluctuations of the incoming x-ray beam. Moreover, we demonstrate the chemical sensitivity and single-shot capability and limitations of HEROS, which enables the technique to track the electronic structural dynamics in matter on femtosecond time scales, making it an ideal probe technique for time-resolved X-ray experiments.

High-energy-resolution photoexcited KN2,3 x-ray-emission measurements were carried out on krypton with the excitation energy tuned around the 1s4p and 1s3d double-excitation thresholds. Comprehensive two-dimensional resonant inelastic x-ray-scattering maps were recorded for the range of excitation and emission energies corresponding to both types of double excitations. The double-excitation signal could be clearly resolved from the dominant 1s ionization signal. The latter was subtracted from the measured maps, yielding isolated 1s4p and 1s3d photoexcitation spectra. Both two-electron excitation spectra are well described by a model spectrum built of consecutive bound-bound discrete transitions and shake-up and shake-off channels giving precise energies and intensities of the corresponding contributions. The obtained results are compared with other existing experimental values based on x-ray-absorption measurements and theoretical predictions.

We report on a high-resolution transmission-type curved crystal spectrometer based on the modified DuMond slit geometry. The spectrometer was developed at the University of Fribourg for the study of photoinduced X-ray spectra. K and L X-ray transitions with energies above about 10 keV can be measured with an instrumental resolution comparable to their natural linewidths. Construction details and operational characteristics of the spectrometer are presented. The variation of the energy resolution as a function of the focal distance and diffraction order is discussed. The high sensitivity of the spectrometer is demonstrated via the 2s-1s dipole-forbidden X-ray transition of Gd which could be observed despite its extremely low intensity. The precision of the instrument is illustrated by comparing the sum of the energies of the Au K-L2 and L2-M3 cascading transitions with the energy of the crossover K-M3 transition as well as by considering the energy differences of the Gd Kα1 X-ray line measured at five different diffraction orders. Finally, to demonstrate the versatility of the spectrometer, it is shown that the latter can also be used for in-house extended X-ray absorption fine structure measurements.

We report on high-resolution measurements of the photoinduced L1M2 and L1M3 x-ray emission lines of Tm-69, Yb-70, Lu-71, Ta-73, W-74, Re-75, Ir-77, Tl-81, 83Bi, and 95Am. From the linewidths of the measured transitions an accurate set of M2 and M3 level widths is determined assuming for the L-1 level widths the values reported by Raboud [P.-A. Raboud et al., Phys. Rev. A 65, 022512 (2002)]. Furthermore, the present experimental M2,3 data set is extended to Hg-80, Th-90, and U-92, using former L1M2,3 high-resolution x-ray emission spectroscopy measurements performed by our group. A detailed comparison of the M2 and M3 level widths determined in the present work with those recommended by Campbell and Papp [J. L. Campbell and T. Papp, At. Data Nucl. Data Tables 77, 1 (2001)] and other available experimental data as well as theoretical predictions is done. The observed abrupt changes of the M2,3 level widths versus atomic number Z can be explained satisfactorily by the cutoffs and onsets of the M2M4N1, respectively M(3)M(4)N3,4,5 and M(3)M(5)N2,3 Coster-Kronig transitions deduced from the semiempirical (Z + 1) approximation. As a spin-off result of this study, precise L1M2 and L1M3 transition energies are obtained for the investigated elements. A very good agreement with transition energies calculated within the many-body perturbation theory is found.

The grazing emission X-ray fluorescence (GEXRF) technique was applied to the analysis of different Al films, with nominal thicknesses in the range of 1 nm to 150 nm, on Si wafers. In GEXRF the sample volume from which the fluorescence intensity is detected is restricted to a near-surface region whose thickness can be tuned by varying the observation angle. This is possible because of the refraction of the fluorescence X-rays and the quite long emission paths within the probed sample. By recording the X-ray fluorescence signal for different shallow emission angles, defined relatively to the flat, smooth sample surface, the deposited Al surface layers of the different samples could be well characterized in terms of layer thickness, layer density, oxidation and surface roughness. The advantages offered by synchrotron radiation and the employed wavelength-dispersive detection setup were profited from. The GEXRF results retrieved were confirmed by complementary measurements. The experimental setup, the principles and advantages of GEXRF and the analysis of the recorded angular intensity profiles will be discussed in details.