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Université de Fribourg

Novel reference-free methods for the determination of the instrumental response of Laue-type bent crystal spectrometers

Szlachetko, Monika ; Hoszowska, Joanna ; Szlachetko, Jakub ; Dousse, Jean-Claude

In: Journal of Analytical Atomic Spectrometry, 2019, vol. 34, no. 11, p. 2325–2332

We report on novel reference-free methods to determine the instrumental resolution of transmission-type bent crystal spectrometers. The novel methods are based on the measurements of a selected X-ray line in several orders of diffraction. It is shown that the angular broadening of the spectrometer and the natural linewidth of the selected transition can be obtained directly from the novel...

Université de Fribourg

A DuMond-type crystal spectrometer for synchrotron-based X-ray emission studies in the energy range of 15–26 keV

Jagodziński, Paweł ; Szlachetko, Jakub ; Dousse, Jean-Claude ; Hoszowska, Joanna ; Szlachetko, Monika ; Vogelsang, U. ; Banaś, Dariusz ; Pakendorf, T. ; Meents, A. ; Bokhoven, Jeroen A. van ; Kubala-Kukuś, Aldona ; Pajek, Marek ; Nachtegaal, Maarten

In: Review of Scientific Instruments, 2019, vol. 90, no. 6, p. 063106

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...

Université de Fribourg

High energy resolution off-resonant spectroscopy: A review

B³achucki, Wojciech ; Hoszowska, Joanna ; Dousse, Jean-Claude ; Kayser, Yves ; Stachura, Regina ; Tyra³a, Krzysztof ; Wojtaszek, Klaudia ; Sá, Jacinto ; Szlachetko, Jakub

In: Spectrochimica Acta Part B: Atomic Spectroscopy, 2017, vol. 136, p. 23–33

We review the high energy resolution off-resonant spectroscopy (HEROS) technique. HEROS probes the unoccupied electronic states of matter in a single-shot manner thanks to the combination of off-resonant excitation around atomic core states using wavelength dispersive X-ray detection setups. In this review we provide a general introduction to the field of X-ray spectroscopy together with the...

Université de Fribourg

In situ high energy resolution off-resonant spectroscopy applied to a time-resolved study of single site Ta catalyst during oxidation

B³achucki, Wojciech ; Szlachetko, Jakub ; Kayser, Yves ; Dousse, Jean-Claude ; Hoszowska, Joanna ; Zeeshan, Faisal ; Sá, Jacinto

In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2017, vol. 411, no. Supplement C, p. 63–67

In the present work high energy resolution off-resonant X-ray spectroscopy (HEROS) was employed at a synchrotron to study a silica supported Ta(V) bisalkyl catalyst activated in hydrogen. The Ta Lα1 HEROS spectra were measured during oxidation of the starting complex and the relative species’ concentration was successfully retrieved as a function of time using the fingerprint HEROS spectra...

Université de Fribourg

Double K-shell photoionization and hypersatellite x-ray transitions of 12⩽Z⩽23 atoms

Hoszowska, Joanna ; Dousse, Jean-Claude ; Cao, Wei ; Fennane, Karima ; Kayser, Yves ; Szlachetko, Monika ; Szlachetko, Jakub ; Kavčič, Matjaz

In: Physical Review A, 2010, vol. 82, no. 6, p. 063408

Single-photon double K-shell ionization of low-Z neutral atoms in the range 12⩽Z⩽23 is investigated. The experimental method was based on measurements of the high- resolution Kαh hypersatellite x-ray spectra following the radiative decay of the K-shell double-vacancy states excited by monochromatic synchrotron radiation. The photon energy dependence of the double K-shell ionization was...

Université de Fribourg

Establishing nonlinearity thresholds with ultraintense X-ray pulses

Szlachetko, Jakub ; Hoszowska, Joanna ; Dousse, Jean-Claude ; Nachtegaal, Maarten ; Błachucki, Wojciech ; Kayser, Yves ; Sà, Jacinto ; Messerschmidt, Marc ; Boutet, Sebastien ; Williams, Garth J. ; David, Christian ; Smolentsev, Grigory ; Bokhoven, Jeroen A. van ; Patterson, Bruce D. ; Penfold, Thomas J. ; Knopp, Gregor ; Pajek, Marek ; Abela, Rafael ; Milne, Christopher J.

In: Scientific Reports, 2016, vol. 6, p. 33292

X-ray techniques have evolved over decades to become highly refined tools for a broad range of investigations. Importantly, these approaches rely on X-ray measurements that depend linearly on the number of incident X-ray photons. The advent of X-ray free electron lasers (XFELs) is opening the ability to reach extremely high photon numbers within ultrashort X-ray pulse durations and is leading...

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

Real time determination of the electronic structure of unstable reaction intermediates during Au₂O₃ Reduction

Szlachetko, Jakub ; Sá, Jacinto ; Nachtegaal, Maarten ; Hartfelder, Urs ; Dousse, Jean-Claude ; Hoszowska, Joanna ; Fernandes, Daniel Luis Abreu ; Shi, Hongqing ; Stampfl, Catherine

In: The Journal of Physical Chemistry Letters, 2014, vol. 5, no. 1, p. 80–84

Chemical reactions are always associated with electronic structure changes of the involved chemical species. Determining the electronic configuration of an atom allows probing its chemical state and gives understanding of the reaction pathways. However, often the reactions are too complex and too fast to be measured at in situ conditions due to slow and/or insensitive experimental techniques. A...

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