# CFEL-DESYT

 2019-03-2008:43 [PUBDB-2019-01624] Journal Article Welsch, R. Probing photodissociation dynamics using ring polymer molecular dynamics The journal of chemical physics 150(11), 114105 (2019) [10.1063/1.5086218]   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.: PDF PDF (PDFA); 2019-03-1910:24 [PUBDB-2019-01603] Journal Article Santra, R. Time-resolved x-ray/optical pump-probe simulations on $\mathrm{N_2}$ molecules Structural dynamics 6(2), 024101 (2019) [10.1063/1.5053995]   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 [...] OpenAccess: PDF PDF (PDFA); 2019-02-2108:34 [PUBDB-2019-01191] Journal Article Santra, R. Time-dependent QED approach to x-ray nonlinear Compton scattering Physical review / A 99(2), 022120 (2019) [10.1103/PhysRevA.99.022120]   Motivated by a recent experiment [Fuchs et al., Nat. Phys [...] OpenAccess: PDF PDF (PDFA); 2019-02-2013:59 [PUBDB-2019-01181] Journal Article et al X-ray induced damage of B$_4$C-coated bilayer materials under various irradiation conditions Scientific reports 9(1), 2029 (2019) [10.1038/s41598-019-38556-0]   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 [...] OpenAccess: PDF PDF (PDFA); 2019-02-0413:49 [PUBDB-2019-00936] Journal Article et al Femtosecond phase-transition in hard x-ray excited bismuth Scientific reports 9(1), 602 (2019) [10.1038/s41598-018-36216-3]   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 [...] OpenAccess: PDF PDF (PDFA); 2019-02-0413:38 [PUBDB-2019-00935] Journal Article et al Simulated XUV photoelectron spectra of THz-pumped liquid water The journal of chemical physics 150(4), 044505 (2019) [10.1063/1.5054272]   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.: PDF PDF (PDFA); 2018-12-2009:22 [PUBDB-2018-05775] Journal Article Welsch, R. Infrared-laser-pulse-enhanced ultrafast fragmentation of $N_2^{2+}$ following Auger decay: Mixed quantum-classical simulations Physical review / A 98(6), 063421 (2018) [10.1103/PhysRevA.98.063421]   We employ mixed quantum-classical molecular dynamics simulations to investigate the fragmentation of $N_2$ molecules after core-level photoionization by an x-ray laser, subsequent Auger decay, and followed by a femtosecond IR pulse that interacts with $N_2^{2+}$. The delayed IR pulse couples the dissociative electronic states of $N_2^{2+}$ with electronic states that can support long-lived vibrational resonances [...] OpenAccess: PDF PDF (PDFA); 2018-12-0509:40 [PUBDB-2018-05211] Journal Article et al Ultrafast nuclear dynamics in the doubly-core-ionized water molecule observed via Auger spectroscopy Physical review / A 98(6), 063403 (2018) [10.1103/PhysRevA.98.063403]   We present a combined experimental and theoretical study of the Auger-emission spectrum following double core ionization and excitation of gas-phase water molecules with hard-x-ray synchrotron radiation above the O $K^{−2}$ threshold. We observe an indication of ultrafast proton motion occurring within the 1.5 fs lifetime of the double-core-hole (DCH) states in water [...] OpenAccess: PDF PDF (PDFA); 2018-12-0509:31 [PUBDB-2018-05209] Journal Article Santra, R. Theory of x-ray scattering from laser-driven electronic systems Physical review / B 98(22), 224302 (2018) [10.1103/PhysRevB.98.224302]   We describe, within the framework of quantum electrodynamics, an interaction between a nonresonant hard x-ray pulse and an electronic system in the presence of a temporally periodic laser field driving electron dynamics in this system. We apply Floquet theory to describe the laser-driven electronic system, and then obtain the scattering probability of an arbitrary nonresonant x-ray pulse from such a system employing the density-matrix formalism [...] OpenAccess: PDF PDF (PDFA); 2018-10-1109:55 [PUBDB-2018-03750] Journal Article et al Relativistic and resonant effects in the ionization of heavy atoms by ultra-intense hard X-rays Nature Communications 9(1), 4200 (2018) [10.1038/s41467-018-06745-6]   An accurate description of the interaction of intense hard X-ray pulses with heavy atoms,which is crucial for many applications of free-electron lasers, represents a hitherto unresolvedchallenge for theory because of the enormous number of electronic configurations andrelativistic effects, which need to be taken into account. Here we report results on multipleionization of xenon atoms by ultra-intense (about 1019W/cm2) femtosecond X-ray pulses atphoton energies from 5.5 to 8.3 keV and present a theoretical model capable of reproducingthe experimental data in the entire energy range. [...] OpenAccess: PDF PDF (PDFA);