A5013085278- Advanced X-ray Imaging Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Electron Microscopy Techniques and Applications
- Laser-Matter Interactions and Applications
- Atomic and Molecular Physics
- Crystallography and Radiation Phenomena
- Advanced Chemical Physics Studies
- Laser-Plasma Interactions and Diagnostics
- Ion-surface interactions and analysis
- Spectroscopy and Quantum Chemical Studies
- Particle Accelerators and Free-Electron Lasers
- Enzyme Structure and Function
- X-ray Diffraction in Crystallography
- Mass Spectrometry Techniques and Applications
- High-pressure geophysics and materials
- Advanced Fiber Laser Technologies
- Laser-induced spectroscopy and plasma
- Electron and X-Ray Spectroscopy Techniques
- Crystallization and Solubility Studies
- Laser Design and Applications
- Inorganic Chemistry and Materials
- Hydrogen Storage and Materials
- Inorganic Fluorides and Related Compounds
- Gyrotron and Vacuum Electronics Research
- Magnetism in coordination complexes
Center for Free-Electron Laser Science
2015-2024
Deutsches Elektronen-Synchrotron DESY
2015-2024
Universität Hamburg
2015-2024
Max Planck Institute for the Structure and Dynamics of Matter
2013-2022
Hamburg Centre for Ultrafast Imaging
2013-2022
University of Science and Technology Beijing
2015
University of Kansas
2008-2010
Korea Advanced Institute of Science and Technology
1999-2001
The nonlinear absorption mechanisms of neon atoms to intense, femtosecond kilovolt x rays are investigated. production Ne(9+) is observed at x-ray frequencies below the Ne(8+), 1s(2) edge and demonstrates a clear quadratic dependence on fluence. Theoretical analysis shows that combination two-photon ionization Ne(8+) ground state high-order sequential process involving single-photon transient excited states time scale faster than Auger decay. We find direct cross section orders magnitude...
Abstract Following structural dynamics in real time is a fundamental goal towards better understanding of chemical reactions. Recording snapshots individual molecules with ultrashort exposure times key ingredient this goal, as atoms move on femtosecond (10 −15 s) timescales. For condensed-phase samples, ultrafast, atomically resolved structure determination has been demonstrated using X-ray and electron diffraction. Pioneering experiments have also started addressing gaseous samples....
X-ray free-electron lasers (FELs) are promising tools for structural determination of macromolecules via coherent x-ray scattering. During ultrashort and ultraintense pulses with an atomic-scale wavelength, samples subject to radiation damage possibly become highly ionized, which may influence the quality scattering patterns. We develop a toolkit treat detailed ionization, relaxation, dynamics atom within consistent theoretical framework. The problem including is investigated as function FEL...
We have investigated multiphoton multiple ionization dynamics of xenon atoms using a new x-ray free-electron laser facility, SPring-8 Angstrom Compact free electron LAser (SACLA) in Japan, and identified that Xen+ with n up to 26 is produced at photon energy 5.5 keV. The observed high charge states (n≥24) are via five-photon absorption, evidencing the occurrence absorption involving deep inner shells. A newly developed theoretical model, which shows good agreement experiment, elucidates...
The multi-wavelength anomalous diffraction (MAD) method is used to determine phase information in x-ray crystallography by employing dispersion corrections from heavy atoms on coherent scattering. X-ray free-electron lasers (FELs) show promise for revealing the structure of single molecules or nanocrystals within femtoseconds, but problem remains largely unsolved. Due ultrabrightness FEL, samples experience severe electronic radiation damage, especially atoms, which hinders direct...
Dense plasmas, found in stellar interiors, are composed of atoms with decreased ionization potentials compared isolated atoms. Researchers have developed a new model to explain the potential data, successfully reproducing results that previous models could not.
Rapid development of X-ray free-electron laser (XFEL) science has taken place in recent years owing to the consecutive launch large-scale XFEL instruments around world. Research areas such as warm dense matter physics and coherent imaging take advantage unprecedentedly high intensities XFELs. A single pulse can induce very complex dynamics within initiated by core-hole photoionization. Owing this complexity, theoretical modeling revealing details excitation relaxation irradiated is important...
Abstract Using electron spectroscopy, we have investigated nanoplasma formation from noble gas clusters exposed to high-intensity hard-x-ray pulses at ~5 keV. Our experiment was carried out the SPring-8 Angstrom Compact free LAser (SACLA) facility in Japan. Dedicated theoretical simulations were performed with molecular dynamics tool XMDYN. We found that this unprecedented wavelength regime is a highly indirect process. In argon investigated, mainly formed through secondary cascading...
Two new one-dimensional single azide-bridged metal(II) compounds [[M(5-methylpyrazole)4(N3)]n](ClO4)n(H2O)n [M = Co (1a), Ni (2a)] were prepared by treating an M(II) ion with stoichiometric amount of sodium azide in the presence four equivalents 3(5)-methylpyrazole ligand. The isostructural 1a and 2a crystallize monoclinic space group P2(1)/n. bridging ligands have a unique end-to-end coordination mode that brings two neighboring metal centers into cis-position respect to unit form...
We present a Floquet treatment of multiphoton quantum interference in strongly driven superconducting flux qubit. The periodically time-dependent Schr\"odinger equation can be reduced to an equivalent time-independent infinite-dimensional matrix eigenvalue problem. For resonant or nearly transitions, we extend the generalized Van Vleck (GVV) degenerate high-order perturbation theory for Hamiltonian, allowing reduction $N\ifmmode\times\else\texttimes\fi{}N$ effective where $N$ is number...
When atoms and molecules are irradiated by an x-ray free-electron laser (XFEL), they highly ionized via a sequence of one-photon ionization relaxation processes. To describe the dynamics during XFEL pulses, rate equation model has been employed. Even though this is straightforward for case light atoms, it generates huge number coupled equations heavy like xenon, which not trivial to solve directly. Here, we employ Monte Carlo method address problem investigate xenon induced pulses at photon...
The sequential inner-shell multiple ionization of krypton was investigated at the Linac Coherent Light Source using ion time-of-flight spectroscopy photon energies above (2 keV) and below (1.5 $L$ edge with two x-ray pulse lengths (5 80 fs, nominally) various energies. At 2.5 mJ energy, charge states up to Kr${}^{17+}$ were recorded for $M$-shell Kr${}^{21+}$ $L$-shell ionization. Comparing experimental state distribution Monte Carlo rate-equation calculations, we find a strong enhancement...
We present the implementation of an electronic-structure approach dedicated to ionization dynamics molecules interacting with x-ray free-electron laser (XFEL) pulses. In our scheme, molecular orbitals for core-hole states are represented by linear combination numerical atomic that solutions corresponding states. demonstrate scheme efficiently calculates all possible multiple-hole configurations formed during XFEL The method is suitable investigate multiphoton multiple and accompanying...
Spin–orbit effects on the bond lengths and dissociation energies of sixth- seventh-row p-block element monohydrides MH(M=Tl–Rn 113–118) are evaluated using relativistic effective core potentials at coupled-cluster level theory. play a dominant role in determination molecular properties for hydrides. hydrides qualitatively similar to, but substantially larger than those sixth-row homologs due to enormous spin–orbit splitting 7p orbitals. interactions change by −0.02∼+0.03 Å −0.21∼+0.21 ,...
A hydrogen- and covalent-bonded 3D array, [Mn(bpe)(H(2)O)(4)](n)()(ClO(4))(2)(n)()(bpe)(4)(n)()(H(2)O)(2)(n)() (2) [bpe = 1,2-bis(4-pyridyl)ethane], a network, [Mn(bpe)(1.5)(H(2)O)(tp)](n)()(H(2)O)(n)() (3) [tp terephthalate], 2D sheet, [Mn(bpe)(N(3))(2)](n)() (4), have been synthesized characterized by spectroscopic data single-crystal X-ray diffraction studies. Complex 2 contains two types of packing bpe molecules: One type molecules (=N31-bpe symmetry-related bpe) run along the chain...
We perform an ab initio study of multiphoton ionization (MPI) carbon dioxide in intense linearly polarized laser pulses with arbitrary molecular orientation by means a time-dependent density-functional theory (TDDFT) proper long-range potential. develop Voronoi-cell finite difference method highly adaptive grids for accurate solution the TDDFT equations. Our results demonstrate that dependence MPI is determined multiple orbital contributions and electron correlation effects are significant....
We have investigated multiphoton multiple ionization of argon and xenon atoms at 5 keV using a new x-ray free electron laser (XFEL) facility, the SPring-8 Angstrom Compact LAser (SACLA) in Japan. The experimental results are compared with theoretical presented here. absolute fluence XFEL pulse has been determined help calculations utilizing two-photon processes atom. high charge states up to +22 observed for Xe comparison point occurrence sequential L-shell absorption resonance-enabled ionization.
We investigate the possible reasons for discrepancy between theoretical two-photon ionization cross section, $\ensuremath{\sim}\phantom{\rule{-0.16em}{0ex}}{10}^{\ensuremath{-}56}$ ${\mathrm{cm}}^{4}\phantom{\rule{0.16em}{0ex}}\mathrm{s}$, of Ne${}^{8+}$ obtained within perturbative nonrelativistic framework monochromatic light [S. Novikov and A. Hopersky, J. Phys. B 34, 4857 (2001)] experimental value, $7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}54}$ reported in [G. Doumy et...
We present a theoretical investigation of x-ray multiphoton ionization dynamics polyatomic molecules, based on the rate equation model and molecular electronic structure calculations. An efficient numerical procedure is developed to calculate photoionization cross sections, Auger rates, fluorescence rates for all possible multiple-hole configurations molecules. investigate charge-state distribution water molecule after interaction with an intense pulse discuss its dependence fluence duration...
The ultrafast structural dynamics of water following inner-shell ionization is a crucial issue in high-energy radiation chemistry. We have exposed isolated molecules to short x-ray pulse from free-electron laser and detected momenta all produced ions coincidence. By combining experimental results theoretical modeling, we can image dissociation individual unprecedented detail. reveal significant molecular H2O2+, such as asymmetric deformation bond-angle opening, leading two-body or three-body...
A recent experiment [Phys. Rev. Lett. 102, 073902 (2009)] has demonstrated that elliptically polarized high-order harmonic generation can be produced from linearly driving fields for aligned molecular systems. In order to reveal the underlying physical mechanisms of elliptical harmonics, we present fully ab initio and high-precision calculations analyses amplitude, phase, polarization state radiation hydrogen ions with arbitrary orientation. We find high ellipticity arises orbital symmetry...
We present results of single-shot resonant magnetic scattering experiments Co/Pt multilayer systems using 100 fs long ultraintense pulses from an extreme ultraviolet (XUV) free-electron laser. An x-ray-induced breakdown the channel during pulse duration is observed at fluences 5 J/cm(2). Simultaneously, speckle contrast high-fluence pattern significantly reduced. performed simulations nonequilibrium evolution system XUV duration. find that electronic state sample strongly perturbed first few...