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Université de Fribourg

X-ray two-photon absorption with high fluence XFEL pulses

Hoszowska, Joanna ; Szlachetko, Jakub ; Dousse, Jean-Claude ; Błachucki, W. ; Kayser, Yves ; Milne, Ch. ; Pajek, M. ; Boutet, S. ; Messerschmidt, M. ; Williams, G. ; Chantler, C. T.

In: Journal of Physics: Conference Series, 2015, vol. 635, no. 10, p. 102009

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/Ų. Two-photon absorption leading to K-shell hollow atom...

Université de Fribourg

Wavelength-dispersive spectrometer for X-ray microfluorescence analysis at the X-ray microscopy beamline ID21 (ESRF)

Szlachetko, Jakub ; Cotte, M. ; Morse, J. ; Salomé, M. ; Jagodzinski, P. ; Dousse, Jean-Claude ; Hoszowska, Joanna ; Kayser, Yves ; Susini, J.

In: Journal of Synchrotron Radiation, 2010, vol. 17, no. 3, p. 400-408

The development of a wavelength-dispersive spectrometer for microfluorescence analysis at the X-ray Microscopy ID21 beamline of the European Synchrotron Radiation Facility (ESRF) is reported. The spectrometer is based on a polycapillary optic for X-ray fluorescence collection and is operated in a flat-crystal geometry. The design considerations as well as operation characteristics of the...

Université de Fribourg

A von Hamos x-ray spectrometer based on a segmented-type diffraction crystal for single-shot x-ray emission spectroscopy and time-resolved resonant inelastic x-ray scattering studies

Szlachetko, Jakub ; Nachtegaal, M. ; Boni, E. de ; Willimann, M. ; Safonova, O. ; Sa, J. ; Smolentsev, G. ; Szlachetko, Monika ; Bokhoven, J. A. van ; Dousse, Jean-Claude ; Hoszowska, Joanna ; Kayser, Yves ; Jagodziński, P. ; Bergamaschi, A. ; Schmitt, Bernd ; David, Christian ; Lücke, A.

In: Review of Scientific Instruments, 2012, vol. 83, no. 10, p. 103105

We report on the design and performance of a wavelength-dispersive type spectrometer based on the von Hamos geometry. The spectrometer is equipped with a segmented-type crystal for x-ray diffraction and provides an energy resolution in the order of 0.25 eV and 1 eV over an energy range of 8000 eV–9600 eV. The use of a segmented crystal results in a simple and straightforward crystal...

Université de Fribourg

Vacuum ultraviolet excitation luminescence spectroscopy of few-layered MoS 2

Pankratov, V ; Hoszowska, Joanna ; Dousse, Jean-Claude ; Huttula, M ; Kis, A ; Krasnozhon, D ; Zhang, M ; Cao, Wei

In: Journal of Physics: Condensed Matter, 2016, vol. 28, no. 1, p. 015301

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...

Université de Fribourg

Vacancy rearrangement processes in multiply ionized atoms

Czarnota, M. ; Pajek, M. ; Banas, D. ; Dousse, Jean-Claude ; Maillard, Yves-Patrick ; Mauron, Olivier ; Raboud, Pierre-Alexandre ; Berset, Michel ; Hoszowska, Joanna ; Slabkowska, K. ; Polasik, M. ; Chmielewska, D. ; Rzadkiewicz, J. ; Sujkowski, Z.

In: Journal of Physics: Conference Series, 2007, vol. 58, no. 1, p. 295

We demonstrate that in order to interpret the x-ray satellite structure of Pd Lα1,2(L₃M4,5) transitions excited by fast O ions, which was measured using a high-resolution von Hamos crystal spectrometer, the vacancy rearrangement processes, taking place prior to the x-ray emission, have to be taken into account. The measured spectra were compared with the predictions...

Université de Fribourg

Theoretical and experimental determination of $L$-shell decay rates, line widths, and fluorescence yields in Ge

Guerra, Michel ; Sampaio, J. M. ; Madeira, T. I. ; Parente, F. ; Indelicato, Paul ; Marques, J. P. ; Santos, J. P. ; Hoszowska, Joanna ; Dousse, Jean-Claude ; Loperetti, L. ; Zeeshan, Faisal ; Müller, M. ; Unterumsberger, R. ; Beckhoff, Burkhard

In: Physical Review A, 2015, vol. 92, no. 2, p. 022507

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 L3FYωL3 was determined at the Physikalisch-Technische...

Université de Fribourg

Synchrotron-radiation-based determination of Xe L-subshell Coster-Kronig yields: a reexamination via high-resolution x-ray spectroscopy

Cao, Wei ; Dousse, Jean-Claude ; Hoszowska, Joanna ; Žitnik, M. ; Kavčič, Matjaz ; Bučar, K.

In: Physical Review A, 2010, vol. 81, no. 1, p. 012501

The xenon L-subshell Coster-Kronig (CK) transition yields were revisited via high-resolution measurements of the Lα1,2 (L₃-M4,5) and Lβ₁ (L₂-M₄) x-ray emission lines. The L x-ray spectra were measured employing a Johansson-type curved crystal spectrometer and energy-tunable synchrotron radiation. The CK yields were derived from the relative L x-ray intensity jumps...

Université de Fribourg

Study of the reactivity of silica supported tantalum catalysts with oxygen followed by in situ HEROS

Błachucki, Wojciech ; Szlachetko, Jakub ; Kayser, Yves ; Dousse, Jean-Claude ; Hoszowska, Joanna ; Fernandes, Daniel L. A. ; Sá, Jacinto

In: Physical Chemistry Chemical Physics, 2015, vol. 17, no. 28, p. 18262–18264

We report on the reactivity of grafted tantalum organometallic catalysts with molecular oxygen. The changes in the local Ta electronic structure were followed by in situ high-energy resolution off-resonant spectroscopy (HEROS). The results revealed agglomeration and formation of Ta dimers, which cannot be reversed. The process occurs independently of starting grafted complex.

Université de Fribourg

Single-photon double K-shell ionization of low-Z atoms

Hoszowska, Joanna ; Kheifets, A. S. ; Dousse, Jean-Claude ; Bray, Igor ; Cao, Wei ; Fennane, Karima ; Kayser, Yves ; Kavčič, Matjaz ; Szlachetko, Jakub ; Szlachetko, Monika

In: Journal of Physics: Conference Series, 2010, vol. 212, no. 1, p. 012006

The photon energy dependence of the double K-shell ionization of light atoms is reported. Experimental double-to-single photoionization cross section ratios for Mg, Al, Si and Ca were obtained from measurements of high-resolution x-ray emission spectra. The double photoionization (DPI) cross-sections for K-shell hollow atom production are compared to convergent close-coupling calculations (CCC)...

Université de Fribourg

The satellites and hypersatellites of Lα1 2 and Lβ1 x-ray transitions in zirconium excited by oxygen and neon ions

Czarnota, M. ; Pajek, M. ; Banaś, D. ; Dousse, Jean-Claude ; Berset, Michel ; Mauron, Olivier ; Maillard, Yves-Patrick ; Raboud, Pierre-Alexandre ; Hoszowska, Joanna ; Polasik, M. ; Słabkowska, K. ; Chmielewska, D. ; Rzadkiewicz, J. ; Sujkowski, Z.

In: Journal of Physics: Conference Series, 2009, vol. 194, p. 152012

The interpretation of L-shell satellites and hypersatellites for Lα1,2 (L₃→M4,5) and Lβ₁ (L₂→M₄) x-ray transitions in zirconium multiply ionized by oxygen and neon ions is reported. The x-ray spectra were measured with a high-resolution von Hamos spectrometer and interpreted in terms the relativistic...