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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

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

High energy resolution off-resonant spectroscopy for X-ray absorption spectra free of self-absorption effects

Błachucki, Wojciech Maria ; Szlachetko, Jakoub ; Hoszowska, Joanna ; Dousse, Jean-Claude ; Kayser, Yves ; Nachtegaal, M. ; Sá, J.

In: Physical Review Letters, 2014, vol. 112, no. 17, p. 173003

X-ray emission spectra recorded in the off-resonant regime carry information on the density of unoccupied states. It is known that by employing the Kramers-Heisenberg formalism, the high energy resolution off-resonant spectroscopy (HEROS) is equivalent to the x-ray absorption spectroscopy (XAS) technique and provides the same electronic state information. Moreover, in the present Letter we...

Université de Fribourg

Subshell-selective x-ray studies of radiative recombination of ${\mathrm{U}}^{92+}$ ions with electrons for very low relative energies

Banaś, D. ; Pajek, M. ; Surzhykov, A. ; Stöhlker, Th. ; Brandau, C. ; Gumberidze, A. ; Kozhuharov, C. ; Beyer, H. F. ; Böhm, S. ; Bosch, F. ; Czarnota, M. ; Chatterjee, S. ; Dousse, Jean-Claude ; Fritzsche, S. ; Hagmann, S. ; Liesen, D. ; Mokler, P. H. ; Müller, A. ; Kumar, A. ; Reuschl, R. ; Sierpowski, D. ; Spillmann, U. ; Szlachetko, Jakoub ; Tashenov, S. ; Trotsenko, S. ; Verma, P. ; Warczak, A.

In: Physical Review A, 2015, vol. 92, no. 3, p. 032710

Radiative recombination (RR) into the K shell and L subshells of U92+ ions interacting with cooling electrons has been studied in an x-ray RR experiment at the electron cooler of the Experimental Storage Ring at GSI. The measured radiative recombination rate coefficients for electron-ion relative energies in the range 0–1000 meV demonstrate the importance of relativistic effects. The observed...

Université de Fribourg

Enhanced radiative recombination of U⁹²⁺ ions with cooling electrons for the K-shell

Banaś, D. ; Beyer, H .F. ; Bosch, F. ; Brandau, C. ; Böhm, S. ; Chatterjee, S. ; Czarnota, M. ; Dousse, Jean-Claude ; Gumberidze, A. ; Hagmann, S. ; Kozhuharov, C. ; Liesen, D. ; Mokler, P. H. ; Müller, A. ; Kumar, A. ; Pajek, M. ; Reuschl, R. ; Schmidt, E. W. ; Sierpowski, D. ; Spillmann, U. ; Surzhykov, A. ; Stöhlker, Th. ; Szlachetko, Jakoub ; Tashenov, S. ; Trotsenko, S. ; Verma, P. ; Warczak, A.

In: Journal of Physics: Conference Series, 2012, vol. 388, no. 6, p. 062044

Observed enhancement of K-shell radiative recombination (RR) of bare uranium ions with cooling electrons is interpreted in terms of of distant transverse collisions in magnetized electron-cooler plasma described within the semiclassical geometrical model (SGM), which was recently proposed. The Monte Carlo simulations based on the proposed approach explains the enhancement measured in RR of...

Université de Fribourg

The enhancement effect in K-shell radiative recombination of U⁹²⁺ ions with cooling electrons

Banaś, D. ; Pajek, M. ; Stöhlker, Th. ; Beyer, H. F. ; Böhm, S. ; Bosch, F. ; Brandau, C. ; Czarnota, M. ; Chatterjee, S. ; Dousse, Jean-Claude ; Fritzsche, S. ; Gumberidze, A. ; Hagmann, S. ; Kozhuharov, C. ; Kumar, A. ; Liesen, D. ; Mokler, P. H. ; Müller, A. ; Reuschl, R. ; Schmidt, E. W. ; Sierpowski, D. ; Spillmann, U. ; Surzhykov, A. ; Szlachetko, J. ; Tashenov, S. ; Trotsenko, S. ; Verma, P. ; Warczak, A.

In: The European Physical Journal: Special Topics, 2009, vol. 169, no. 1, p. 15-18

We report the results of the x-ray radiative recombination (RR) experiment at the electron cooler of the ESR storage ring performed, for the first time, for detuned (off-cooling) electron energies. In this experiment the recombination of stored, decelerated bare uranium ions with electrons in the energy range 0–1000 meV was studied by observing K-RR x-ray photons emitted from direct radiative...

Université de Fribourg

Crystal optics for hard-X-ray spectroscopy of highly charged ions

Beyer, H.F. ; Attia, D. ; Banas, D. ; Bigot, E.-O. Le ; Bosch, F. ; Dousse, Jean-Claude ; Förster, E. ; Gumberidze, A. ; Hagmann, S. ; Heß, S. ; Hoszowska, J. ; Indelicato, P. ; Jagodzinski, P. ; Kozhuharov, Chr. ; Krings, Th. ; Liesen, D. ; Ma, X. ; Manil, B. ; Mohos, I. ; Pajek, M. ; Protić, D. ; Reuschl, R. ; Rzadkiewicz, J. ; Simionovici, A. ; Spillmann, U. ; Stachura, Z. ; Stöhlker, Th. ; Trassinelli, M. ; Trotsenko, S. ; Warczak, A. ; Wehrhan, O. ; Ziegler, E.

In: Spectrochimica Acta Part B: Atomic Spectroscopy, 2009, vol. 64, no. 8, p. 736-743

A twin crystal-spectrometer assembly, operated in the focusing compensated asymmetric Laue geometry has been developed for accurate spectroscopy of fast highly charged heavy ions in the hard-X-ray region. Coupled to the focusing crystal optics is a specially developed two-dimensional position-sensitive X-ray detector which is necessary for retaining spectral resolution also for fast moving...

Université de Fribourg

Distribution of aluminum over different T-sites in ferrierite zeolites studied with aluminum valence to core X-ray emission spectroscopy

Bohinc, R. ; Hoszowska, Joanna ; Dousse, Jean-Claude ; B³achucki, Wojciech Maria ; Zeeshan, Faisal ; Kayser, Yves ; Nachtegaal, Maarten ; Pinar, A. B. ; Bokhoven, Jeroen A. van

In: Physical Chemistry Chemical Physics, 2017, vol. 19, no. 43, p. 29271–29277

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...

Université de Fribourg

Double L₃M ionization of Pd induced by impact with medium-energy electrons

Cao, Wei ; Dousse, Jean-Claude ; Hoszowska, Joanna ; Kavčič, Matjaz ; Kayser, Yves ; Schenker, Jean-Luc ; Žitnik, M.

In: Physical Review A: atomic, molecular and optical physics, 2011, vol. 83, no. 2, p. 022708

The electron-induced L₃M two-step double ionization cross sections of metallic Pd were determined experimentally for incident electron beam energies ranging from the double ionization threshold up to 18 keV. The double L₃M ionization cross sections were derived from the intensity ratios (ILαM:ILα) of the resolved M satellites to the parent diagram lines. The sample was...