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BETA
Agåker, Marcus
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Publications (10 of 34) Show all publications
Sanchez-Gonzalez, A., Micaelli, P., Olivier, C., Barillot, T. R., Ilchen, M., Lutman, A. A., . . . Marangos, J. P. (2017). Accurate prediction of X-ray pulse properties from a free-electron laser using machine learning. Nature Communications, 8, Article ID 15461.
Open this publication in new window or tab >>Accurate prediction of X-ray pulse properties from a free-electron laser using machine learning
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2017 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, article id 15461Article in journal (Refereed) Published
Abstract [en]

Free-electron lasers providing ultra-short high-brightness pulses of X-ray radiation have great potential for a wide impact on science, and are a critical element for unravelling the structural dynamics of matter. To fully harness this potential, we must accurately know the X-ray properties: intensity, spectrum and temporal profile. Owing to the inherent fluctuations in free-electron lasers, this mandates a full characterization of the properties for each and every pulse. While diagnostics of these properties exist, they are often invasive and many cannot operate at a high-repetition rate. Here, we present a technique for circumventing this limitation. Employing a machine learning strategy, we can accurately predict X-ray properties for every shot using only parameters that are easily recorded at high-repetition rate, by training a model on a small set of fully diagnosed pulses. This opens the door to fully realizing the promise of next-generation high-repetition rate X-ray lasers.

Place, publisher, year, edition, pages
Nature Publishing Group, 2017
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-327226 (URN)10.1038/ncomms15461 (DOI)000402745000001 ()28580940 (PubMedID)
Available from: 2017-08-25 Created: 2017-08-25 Last updated: 2017-11-29Bibliographically approved
Urpelainen, S., Sathe, C., Grizolli, W., Agåker, M., Head, A. R., Andersson, M., . . . Hennies, F. (2017). The SPECIES beamline at the MAX IV Laboratory: a facility for soft X-ray RIXS and APXPS. Paper presented at 9th International Workshop on X-Ray Radiation Damage to Biological Crystalline Samples, MAR 09-11, 2016, Lund, SWEDEN. Journal of Synchrotron Radiation, 24, 344-353
Open this publication in new window or tab >>The SPECIES beamline at the MAX IV Laboratory: a facility for soft X-ray RIXS and APXPS
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2017 (English)In: Journal of Synchrotron Radiation, ISSN 0909-0495, E-ISSN 1600-5775, Vol. 24, p. 344-353Article in journal, Meeting abstract (Refereed) Published
Abstract [en]

SPECIES is an undulator-based soft X-ray beamline that replaced the old I511 beamline at the MAX II storage ring. SPECIES is aimed at high-resolution ambient-pressure X-ray photoelectron spectroscopy (APXPS), near-edge X-ray absorption fine-structure (NEXAFS), X-ray emission spectroscopy (XES) and resonant inelastic X-ray scattering (RIXS) experiments. The beamline has two branches that use a common elliptically polarizing undulator and monochromator. The beam is switched between the two branches by changing the focusing optics after the monochromator. Both branches have separate exit slits, refocusing optics and dedicated permanent endstations. This allows very fast switching between two types of experiments and offers a unique combination of the surface-sensitive XPS and bulk-sensitive RIXS techniques both in UHV- and at elevated ambient-pressure conditions on a single beamline. Another unique property of the beamline is that it reaches energies down to approximately 27 eV, which is not obtainable on other current APXPS beamlines. This allows, for instance, valence band studies under ambient-pressure conditions. In this article the main properties and performance of the beamline are presented, together with selected showcase experiments performed on the new setup.

Keywords
RIXS, APXPS, beamlines, MAX IV
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-315845 (URN)10.1107/S1600577516019056 (DOI)000391724900037 ()28009577 (PubMedID)
Conference
9th International Workshop on X-Ray Radiation Damage to Biological Crystalline Samples, MAR 09-11, 2016, Lund, SWEDEN
Funder
Swedish Research Council, 2009-5861Knut and Alice Wallenberg Foundation
Available from: 2017-02-21 Created: 2017-02-21 Last updated: 2017-11-29Bibliographically approved
Kimberg, V., Sanchez-Gonzalez, A., Mercadier, L., Weninger, C., Lutman, A., Ratner, D., . . . Rohringer, N. (2016). Stimulated X-ray Raman scattering - a critical assessment of the building block of nonlinear X-ray spectroscopy. Faraday discussions (Online), 194, 305-324
Open this publication in new window or tab >>Stimulated X-ray Raman scattering - a critical assessment of the building block of nonlinear X-ray spectroscopy
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2016 (English)In: Faraday discussions (Online), ISSN 1359-6640, E-ISSN 1364-5498, Vol. 194, p. 305-324Article in journal (Refereed) Published
Abstract [en]

With the invention of femtosecond X-ray free-electron lasers (XFELs), studies of light-induced chemical reaction dynamics and structural dynamics reach a new era, allowing for time-resolved X-ray diffraction and spectroscopy. To ultimately probe coherent electron and nuclear dynamics on their natural time and length scales, coherent nonlinear X-ray spectroscopy schemes have been proposed. In this contribution, we want to critically assess the experimental realisation of nonlinear X-ray spectroscopy at current-day XFEL sources, by presenting first experimental attempts to demonstrate stimulated resonant X-ray Raman scattering in molecular gas targets.

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-312397 (URN)10.1039/C6FD00103C (DOI)000392422200014 ()27711899 (PubMedID)
Available from: 2017-01-09 Created: 2017-01-09 Last updated: 2017-11-29Bibliographically approved
Rohringer, N., Kimberg, V., Weninger, C., Sanchez-Gonzalez, A., Lutman, A., Maxwell, T., . . . Rubensson, J.-E. (2016). Stimulated X-Ray Raman Scattering with Free-Electron Laser Sources. In: X-RAY LASERS 2014: . Paper presented at 14th International Conference on X-Ray Lasers, MAY 26-30, 2014, Colorado State Univ, Fort Collins, CO (pp. 201-207).
Open this publication in new window or tab >>Stimulated X-Ray Raman Scattering with Free-Electron Laser Sources
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2016 (English)In: X-RAY LASERS 2014, 2016, p. 201-207Conference paper, Published paper (Refereed)
Abstract [en]

Stimulated electronic x-ray Raman scattering is the building block for several proposed x-ray pump probe techniques, that would allow the study of electron dynamics at unprecedented timescales. We present high spectral resolution data on stimulated electronic x-ray Raman scattering in a gas sample of neon using a self-amplified spontaneous emission x-ray free-electron laser. Despite the limited spectral coherence and broad bandwidth of these sources, high-resolution spectra can be obtained by statistical methods, opening the path to coherent stimulated x-ray Raman spectroscopy. An extension of these ideas to molecules and the results of a recent experiment in CO are discussed.

Series
Springer Proceedings in Physics, ISSN 0930-8989 ; 169
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-300141 (URN)10.1007/978-3-319-19521-6_26 (DOI)000378036600026 ()9783319195216; 9783319195209 (ISBN)
Conference
14th International Conference on X-Ray Lasers, MAY 26-30, 2014, Colorado State Univ, Fort Collins, CO
Available from: 2016-08-03 Created: 2016-08-03 Last updated: 2016-08-03Bibliographically approved
Yin, Z., Peters, H. B., Hahn, U., Agåker, M., Hage, A., Reininger, R., . . . Techert, S. (2015). A new compact soft x-ray spectrometer for resonant inelastic x-ray scattering studies at PETRA III. Review of Scientific Instruments, 86(9), Article ID 093109.
Open this publication in new window or tab >>A new compact soft x-ray spectrometer for resonant inelastic x-ray scattering studies at PETRA III
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2015 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 86, no 9, article id 093109Article in journal (Refereed) Published
Abstract [en]

We present a newly designed compact grating spectrometer for the energy range from 210 eV to 1250 eV, which would include the K alpha(1,2) emission lines of vital elements like C, N, and O. The spectrometer is based on a grazing incidence spherical varied line spacing grating with 2400 l/mm at its center and a radius of curvature of 58 542 mm. First, results show a resolving power of around 1000 at an energy of 550 eV and a working spectrometer for high vacuum (10(-4) mbar) environment without losing photon intensity.

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-265597 (URN)10.1063/1.4930968 (DOI)000362573300010 ()26429431 (PubMedID)
Available from: 2015-11-02 Created: 2015-11-02 Last updated: 2017-12-01
Englund, C.-J., Agåker, M., Fredriksson, P., Olsson, A., Johansson, N., Rubensson, J.-E. & Nordgren, J. (2015). An ultra-high vacuum chamber for scattering experiments featuring in-vacuum continuous in-plane variation of the angle between entrance and exit vacuum ports. Review of Scientific Instruments, 86(9), Article ID 095110.
Open this publication in new window or tab >>An ultra-high vacuum chamber for scattering experiments featuring in-vacuum continuous in-plane variation of the angle between entrance and exit vacuum ports
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2015 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 86, no 9, article id 095110Article in journal (Refereed) Published
Abstract [en]

A concept that enables in-vacuum continuous variation of the angle between two ports in one plane has been developed and implemented. The vacuum chamber allows for measuring scattering cross sections as a function of scattering angle and is intended for resonant inelastic X-ray scattering experiments. The angle between the ports can be varied in the range of 30 degrees-150 degrees, while the pressure change is less than 2 x 10(-10) mbars.

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-265596 (URN)10.1063/1.4931041 (DOI)000362573300062 ()26429483 (PubMedID)
Funder
Knut and Alice Wallenberg Foundation
Available from: 2015-11-02 Created: 2015-11-02 Last updated: 2017-12-01
Sanchez-Gonzalez, A., Barillot, T. R., Squibb, R. J., Kolorenc, P., Agåker, M., Averbukh, V., . . . Marangos, J. P. (2015). Auger Electron and Photoabsorption Spectra of Glycine in the Vicinity of the Oxygen K-edge Measured with an X-FEL. Journal of Physics B: Atomic, Molecular and Optical Physics, 48(23), Article ID 234004.
Open this publication in new window or tab >>Auger Electron and Photoabsorption Spectra of Glycine in the Vicinity of the Oxygen K-edge Measured with an X-FEL
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2015 (English)In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 48, no 23, article id 234004Article in journal (Refereed) Published
Abstract [en]

We report the first measurement of the near oxygen K-edge auger spectrum of the glycine molecule. Our work employed an x-ray free electron laser as the photon source operated with input photon energies tunable between 527 and 547 eV. Complete electron spectra were recorded at each photon energy in the tuning range, revealing resonant and non-resonant auger structures. Finally ab initio theoretical predictions are compared with the measured above the edge auger spectrum and an assignment of auger decay channels is performed.

Keywords
X-FEL, auger electron, glycine, oxygen, ab initio calculation
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-270416 (URN)10.1088/0953-4075/48/23/234004 (DOI)000365240900005 ()
Available from: 2016-03-14 Created: 2015-12-28 Last updated: 2018-06-26
Terschlüsen, J. A., Agåker, M., Svanqvist, M., Plogmaker, S., Nordgren, J., Rubensson, J.-E., . . . Söderström, J. (2014). Measuring the temporal coherence of a high harmonic generation setup employing a Fourier transform spectrometer for the VUV/XUV. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 768, 84-88
Open this publication in new window or tab >>Measuring the temporal coherence of a high harmonic generation setup employing a Fourier transform spectrometer for the VUV/XUV
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2014 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 768, p. 84-88Article in journal (Refereed) Published
Abstract [en]

In this experiment we used an 800 nm laser to generate high-order harmonics in a gas cell filled with Argon. Of those photons, a harmonic with 42 eV was selected by using a time-preserving grating monochromator. Employing a modified Mach–Zehnder type Fourier transform spectrometer for the VUV/XUV it was possible to measure the temporal coherence of the selected photons to about 6 fs. We demonstrated that not only could this kind of measurement be performed with a Fourier transform spectrometer, but also with some spatial resolution without modifying the XUV source or the spectrometer.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
Fourier transform spectrometer, HHG, Temporal coherence, Spatial coherence, SoftX-ray, XUV
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:uu:diva-236322 (URN)10.1016/j.nima.2014.09.040 (DOI)000344995400013 ()
Funder
Swedish Research Council, 2006-4382Swedish Research Council, 2010-4132Swedish Research Council, 2011-5036Knut and Alice Wallenberg Foundation, 2008.0108Knut and Alice Wallenberg Foundation, personal grant (JS)Carl Tryggers foundation , 12:439Carl Tryggers foundation , 13:423
Available from: 2014-11-17 Created: 2014-11-17 Last updated: 2017-12-05Bibliographically approved
Brandenburg, T., Agåker, M., Atak, K., Pflüger, M., Schwanke, C., Petit, T., . . . Aziz, E. F. (2014). The electronic structure of perfluorodecalin studied by soft X-ray spectroscopy and electronic structure calculations. Physical Chemistry, Chemical Physics - PCCP, 16(42), 23379-23385
Open this publication in new window or tab >>The electronic structure of perfluorodecalin studied by soft X-ray spectroscopy and electronic structure calculations
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2014 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, no 42, p. 23379-23385Article in journal (Refereed) Published
Abstract [en]

Fluorine and carbon K absorption and emission spectra of liquid perfluorodecalin are presented and analyzed in terms of density functional calculations-configuration interaction. A comprehensive view of the electronic structure is given, and site-specific intramolecular interactions are investigated in detail. It is found that, while the outer fluorine atoms have excess charge in the ground state, the lowest excitations must be associated with charge transfer towards the inner carbon atoms.

Keywords
Thomas Hobbes, cocodrilo, alegoría, Leviatán, Cristianidad, religión pagana
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-237721 (URN)10.1039/c4cp03153a (DOI)000343750700051 ()25263001 (PubMedID)
Available from: 2014-12-04 Created: 2014-12-04 Last updated: 2017-12-05Bibliographically approved
Agåker, M., Andersson, J., Englund, J., Rausch, J., Rubensson, J.-E. & Nordgren, J. (2011). Spectroscopy in the vacuum-ultraviolet. Nature Photonics, 5, 248
Open this publication in new window or tab >>Spectroscopy in the vacuum-ultraviolet
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2011 (English)In: Nature Photonics, ISSN 1749-4885, E-ISSN 1749-4893, Vol. 5, p. 248-Article in journal (Refereed) Published
National Category
Atom and Molecular Physics and Optics Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-281291 (URN)
Available from: 2016-03-22 Created: 2016-03-22 Last updated: 2017-11-30
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