A5006895718- X-ray Spectroscopy and Fluorescence Analysis
- Atomic and Molecular Physics
- Advanced Chemical Physics Studies
- Advanced X-ray Imaging Techniques
- Electron and X-Ray Spectroscopy Techniques
- Crystallography and Radiation Phenomena
- Laser-Matter Interactions and Applications
- Quantum, superfluid, helium dynamics
- Spectroscopy and Quantum Chemical Studies
- Advanced Electron Microscopy Techniques and Applications
- Spectroscopy and Laser Applications
- Chemical Thermodynamics and Molecular Structure
- Particle Accelerators and Free-Electron Lasers
- High-pressure geophysics and materials
- Nuclear Physics and Applications
- Muon and positron interactions and applications
- Laser-induced spectroscopy and plasma
- Boron and Carbon Nanomaterials Research
- Iron-based superconductors research
- Rare-earth and actinide compounds
- Terahertz technology and applications
- Photocathodes and Microchannel Plates
- Crystal Structures and Properties
- Cold Atom Physics and Bose-Einstein Condensates
- Machine Learning in Materials Science
Uppsala University
2014-2025
MAX IV Laboratory
2020-2025
Lund University
2020-2025
Free-electron lasers providing ultra-short high-brightness pulses of X-ray radiation have great potential for a wide impact on science, and are critical element unravelling the structural dynamics matter. To fully harness this potential, we must accurately know properties: intensity, spectrum temporal profile. Owing to inherent fluctuations in free-electron lasers, mandates full characterization properties each every pulse. While diagnostics these exist, they often invasive many cannot...
The nonlinear interaction of x rays with matter is at the heart understanding and controlling ultrafast molecular dynamics from an atom-specific viewpoint, providing new scientific analytical opportunities to explore structure small quantum systems. At increasingly high x-ray intensity, sensitivity ultrashort pulses specific electronic states emerging short-lived transient intermediates particular relevance for our fundamental multiphoton absorption processes. In this work, intense...
SPECIES is an undulator-based soft X-ray beamline that replaced the old I511 at MAX II storage ring. aimed high-resolution ambient-pressure photoelectron spectroscopy (APXPS), near-edge absorption fine-structure (NEXAFS), emission (XES) and resonant inelastic scattering (RIXS) experiments. The has two branches use a common elliptically polarizing undulator monochromator. beam switched between by changing focusing optics after Both have separate exit slits, refocusing dedicated permanent...
A new experimental technique uses an x-ray free-electron laser to reveal charge dynamics within a molecule following removal of electron, paving the way for broader understanding molecular transfer.
Resonant inelastic x-ray scattering (RIXS) is a major method for investigation of electronic structure and dynamics, with applications ranging from basic atomic physics to materials science. In RIXS applied inversion-symmetric systems, it has generally been accepted that strict parity selectivity applies in the sub–kilo–electron volt region. contrast, we show selection rule violated spectra free homonuclear diatomic O 2 molecule. By analyzing spectral dependence on angle, demonstrate...
Nonlinear x-ray spectroscopy The extension of nonlinear optics to the spectral domain is a promising direction in development spectroscopy. Although theoretical concepts were developed decades ago, scientists still struggle implement them because elusive nature effects. Eichmann et al. now present atomic momentum (AMS), which based on detection scattered atom after transfer from photons (see Perspective by Pfeifer). authors show how AMS can observe stimulated Raman scattering signals at neon...
Dissociation upon sulfur <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>K</a:mi></a:math>-shell excitation or ionization of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:msub><c:mrow><c:mi>SF</c:mi></c:mrow><c:mrow><c:mn>6</c:mn></c:mrow></c:msub></c:mrow></c:math> is studied by <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mi>L</e:mi></e:math>-shell emission spectroscopy using synchrotron radiation...
With the invention of femtosecond X-ray free-electron lasers (XFELs), studies light-induced chemical reaction dynamics and structural reach a new era, allowing for time-resolved diffraction spectroscopy. To ultimately probe coherent electron nuclear on their natural time length scales, nonlinear spectroscopy schemes have been proposed. In this contribution, we want to critically assess experimental realisation at current-day XFEL sources, by presenting first attempts demonstrate stimulated...
A recent experimental study [J.-E. Rubensson et al., Phys. Rev. Lett. 83, 947 (1999)] measured a significant fluorescence yield of the He( ${2lnl}^{\ensuremath{'}}$) photoexcited resonances, showing major qualitative differences from nonrelativistic predictions. We present further theoretical these states, and perform $R$-matrix multichannel quantum defect theory calculations to extract ionization cross sections. These results are in excellent agreement with newer, higher-resolution...
X-ray-emission threshold-electron coincidence spectroscopy has been applied to ${\mathrm{N}}_{2}$, ${\mathrm{O}}_{2}$, and ${\mathrm{N}}_{2}\mathrm{O}$. The main features of the spectra can be interpreted as conventional core level threshold electron spectra, free from postcollision interaction effects. relative cross sections for adiabatic ionization close-lying hole states vibrational substates are presented. results compared theoretical predictions state-of-the-art photoelectron discussed...
Abstract Warm dense matter is at the boundary between a plasma and condensed phase plays role in astrophysics, planetary science inertial confinement fusion research. However, its electronic structure ionic upon irradiation with strong laser pulses remain poorly understood. Here, we use an intense ultrafast X-ray free-electron pulse to simultaneously create characterize warm copper using L -edge absorption spectroscopy over large intensity range. Below of 10 15 W cm −2 , peak below edge...
We present a newly designed compact grating spectrometer for the energy range from 210 eV to 1250 eV, which would include Kα1,2 emission lines of vital elements like C, N, and O. The is based on grazing incidence spherical varied line spacing with 2400 l/mm at its center radius curvature 58 542 mm. First, results show resolving power around 1000 an 550 working high vacuum (10−4 mbar) environment without losing photon intensity.
Resonant inelastic x-ray scattering spectra excited at the ${\ensuremath{\pi}}^{*}$-resonance of nitrogen molecule are presented. Well-resolved vibrational excitations in electronic ground state, and $3{\ensuremath{\sigma}}_{g}^{\ensuremath{-}1}1{\ensuremath{\pi}}_{g}^{1}\phantom{\rule{4pt}{0ex}}{a}^{1}{\mathrm{\ensuremath{\Pi}}}_{g}$ state observed. The analyzed within Kramers-Heisenberg formalism, importance lifetime-vibrational interference effects is highlighted. In addition, strongly...
Abstract X-ray photoelectron spectroscopy (XPS) measures the binding energy of core-level electrons, which are well-localised to specific atomic sites in a molecular system, providing valuable information on local chemical environment. The technique relies measuring spectrum upon x-ray photoionisation, and resolution is often limited by bandwidth ionising pulse. This particularly problematic for time-resolved XPS, where desired time enforces fundamental lower limit source. In this work, we...
We report on a combined experimental and theoretical study ${\mathrm{CrI}}_{3}$ single crystals by employing the polarization dependence of resonant inelastic x-ray scattering (RIXS). Our investigations reveal multiple Cr $3d$ orbital splitting ($dd$ excitations) as well magnetic dichroism (MD) in RIXS spectra. The $dd$ excitation energies are similar two sides ferromagnetic transition temperature, ${T}_{C}\ensuremath{\sim}61$ K, although MD is predominant at 0.4 T field below ${T}_{C}$....
During beam time at a research facility, alignment and optimization of instrumentation, such as spectrometers, is time-intensive task often needs to be performed multiple times throughout the operation an experiment. Despite motorization individual components, automated solutions are not always available. In this study, novel approach that combines optimisers with neural network surrogate models significantly reduce overhead for mobile soft X-ray spectrometer proposed. Neural networks were...
A dramatic electric field dependence has been observed in the fluorescence yield spectrum of doubly excited states helium, where a rich phenomenology is encountered below threshold. Fluorescence yields certain can be tuned to zero, while other dipole-forbidden are significantly enhanced, for fields much weaker than 1 kV/cm. Using an R-matrix multichannel quantum defect theory, spherical-to-parabolic frame transformation method, we able reproduce main features spectrum, and discuss...
We report the first measurement of near oxygen K-edge auger spectrum glycine molecule. Our work employed an x-ray free electron laser as photon source operated with input energies tunable between 527 and 547 eV. Complete spectra were recorded at each energy in tuning range, revealing resonant non-resonant structures. Finally ab initio theoretical predictions are compared measured above edge assignment decay channels is performed.
Radiative decay spectra of doubly excited states in He have been measured after selective excitation with monochromatized synchrotron radiation. The are excellent agreement predictions based on calculations.
An influence of static magnetic fields on the fluorescence yield spectrum He in vicinity N = 2 thresholds has been observed. The experimental results are excellent agreement with predictions based multichannel quantum defect theory, and it is demonstrated that Rydberg electron l mixing due to diamagnetic interaction essential for description observed intensity enhancement.
With the introduction of multi-bend achromats in new fourth-generation storage rings emittance has decreased by an order magnitude resulting increased brightness. However, higher brightness comes with smaller beam sizes and narrower radiation cones. As a consequence, requirements on mechanical stability regarding beamline components increases. Here innovative five-axis parallel kinematic mirror unit for use soft X-ray beamlines using off-axis grazing-incidence optics is presented. Using...