CFEL-DESYT

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2019-07-04
12:46
OpenAccess [PUBDB-2019-02638] Journal Article
et al
Theoretical evidence for the sensitivity of charge-rearrangement-enhanced x-ray ionization to molecular size
It was recently discovered that molecular ionization at high x-ray intensity is enhanced, in comparison with that of isolated atoms, through a phenomenon called CREXIM (charge-rearrangement-enhanced x-ray ionization of molecules). X-ray absorption selectively ionizes heavy atoms within molecules, triggering electron transfer from neighboring atoms to the heavy-atom sites and enabling further ionization there [...]
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2019-06-13
09:08
OpenAccess [PUBDB-2019-02472] Journal Article
et al
Ultrafast anisotropic disordering in graphite driven by intense hard X-ray pulses
We present results from the SPring-8 Angstrom Compact free electron LAser (SACLA) X-ray free electron laser (XFEL) facility, using an X-ray pump, X-ray probe scheme to observe ultrafast changes in the structure of heated graphite. The 9.8 keV XFEL beam was focused to give an intensity on the order of  ∼ 10$^{19}$ W/cm$^2$, and the evolution of the diffraction pattern observed up to delays of 300 fs [...]
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2019-06-12
14:56
OpenAccess [PUBDB-2019-02460] Journal Article
et al
xcalib : a focal spot calibrator for intense X-ray free-electron laser pulses based on the charge state distributions of light atoms
The xcalib toolkit has been developed to calibrate the beam profile of an X-ray free-electron laser (XFEL) at the focal spot based on the experimental charge state distributions (CSDs) of light atoms. Characterization of the fluence distribution at the focal spot is essential to perform the volume integrations of physical quantities for a quantitative comparison between theoretical and experimental results, especially for fluence-dependent quantities. [...]
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ddc:550
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2019-04-02
10:40
OpenAccess [PUBDB-2019-01792] Journal Article

Analytical Theory of Attosecond Transient Absorption Spectroscopy of Perturbatively Dressed Systems
Applied Sciences 9(7), 1350 () [10.3390/app9071350] special issue: "Attosecond Science and Technology: Principles and Applications"  GO
A theoretical description of attosecond transient absorption spectroscopy for temporally and spatially overlapping XUV and optical pulses is developed, explaining the signals one can obtain in such an experiment. To this end, we employ a two-stage approach based on perturbation theory, which allows us to give an analytical expression for the transient absorption signal [...]
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2019-03-20
08:43
Embargoed OpenAccess [PUBDB-2019-01624] Journal Article

Probing photodissociation dynamics using ring polymer molecular dynamics
The performance of the ring polymer molecular dynamics (RPMD) approach to simulate typical photodissociation processes is assessed. The correct description of photodissociation requires the calculation of correlation functions or expectation values associated with non-equilibrium initial conditions, which was shown to be possible with RPMD very recently [J. [...]
Published on 2019-03-18. Available in OpenAccess from 2020-03-18.: Download fulltextPDF Download fulltextPDF (PDFA);
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2019-03-19
10:24
OpenAccess [PUBDB-2019-01603] Journal Article

Time-resolved x-ray/optical pump-probe simulations on $\mathrm{N_2}$ molecules
Structural dynamics 6(2), 024101 () [10.1063/1.5053995]  GO
The dynamics of $N_2^{2+}$ dications after x-ray-induced Auger decay and their probing with a delayed infrared probe pulse are theoretically investigated based on a quantum-mechanical model including all relevant electronic states for which wave-packet calculations on ab-initio potential energy curves are performed. Our results demonstrate that the $N_2^{2+}$ yield modulated by the delay of the probe pulse contains dynamical information on the wave-packet evolution in the quasi-bound final electronic states [...]
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2019-02-21
08:34
OpenAccess [PUBDB-2019-01191] Journal Article

Time-dependent QED approach to x-ray nonlinear Compton scattering
Motivated by a recent experiment [Fuchs et al., Nat. Phys [...]
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2019-02-20
13:59
OpenAccess [PUBDB-2019-01181] Journal Article
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X-ray induced damage of B$_4$C-coated bilayer materials under various irradiation conditions
In this report, we analyse X-ray induced damage of B$_4$C-coated bilayer materials under various irradiation geometries, following the conditions of our experiment performed at the free-electron-laser facility SACLA. We start with the discussion of structural damage in solids and damage threshold doses for the experimental system components: B$_4$C, SiC, Mo and Si [...]
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2019-02-04
13:49
OpenAccess [PUBDB-2019-00936] Journal Article
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Femtosecond phase-transition in hard x-ray excited bismuth
The evolution of bismuth crystal structure upon excitation of its $A_{1g}$ phonon has been intensely studied with short pulse optical lasers. Here we present the first-time observation of a hard x-ray induced ultrafast phase transition in a bismuth single crystal at high intensities $(~10^{14} W/cm^2 ).$ The lattice evolution was followed using a recently demonstrated x-ray single-shot probing setup [...]
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2019-02-04
13:38
Embargoed OpenAccess [PUBDB-2019-00935] Journal Article
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Simulated XUV photoelectron spectra of THz-pumped liquid water
Highly intense, sub-picosecond terahertz (THz) pulses can be used to induce ultrafast temperature jumps (T-jumps) in liquid water. A supercritical state of gas-like water with liquid density is established, and the accompanying structural changes are expected to give rise to time-dependent chemical shifts. [...]
Published on 2019-01-29. Available in OpenAccess from 2020-01-29.: Download fulltextPDF Download fulltextPDF (PDFA);
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