# FS-FLASH-B

 2019-07-0917:18 [PUBDB-2019-02682] Journal Article et al Alignment of the aberration-free XUV Raman spectrometer at FLASH Journal of synchrotron radiation 26(1), 18 - 27 (2019) [10.1107/S160057751801576X]   An extreme-ultraviolet (XUV) double-stage Raman spectrometer is permanently installed as an experimental end-station at the PG1 beamline of the soft X-ray/XUV free-electron laser in Hamburg, FLASH. The monochromator stages are designed according to the Czerny–Turner optical scheme, adapted for the XUV photon energy range, with optical elements installed at grazing-incidence angles. [...] Restricted: PDF PDF (PDFA); 2019-07-0917:13 [PUBDB-2019-02681] Journal Article et al Surface structure determination by x-ray standing waves at a free-electron laser New journal of physics 21(3), 033031 (2019) [10.1088/1367-2630/aafa47]   We demonstrate the structural sensitivity and accuracy of the x-ray standing wave technique at a high repetition rate free-electron laser, FLASH at DESY in Hamburg, by measuring the photoelectron yield from the surface SiO$_2$ of Mo/Si multilayers. These experiments open up the possibility to obtain unprecedented structural information of adsorbate and surface atoms with picometer spatial and femtosecond temporal resolution [...] OpenAccess: PDF PDF (PDFA); 2019-07-0916:52 [PUBDB-2019-02679] Journal Article et al Normalized single-shot X-ray absorption spectroscopy at a free-electron laser Optics letters 44(9), 2157 - 2160 (2019) [10.1364/OL.44.002157]   A setup for dispersive X-ray absorption spectroscopy (XAS), employing a new reference scheme, has been implemented and tested at the soft X-ray free-electron laser (FEL) FLASH in Hamburg. A transmission grating was used to split the FEL beam into two copies (signal and reference). [...] OpenAccess: PDF PDF (PDFA); 2019-07-0916:47 [PUBDB-2019-02678] Journal Article et al Wavefront-propagation simulations supporting the design of a time-delay compensating monochromator beamline at FLASH2 Journal of synchrotron radiation 26(3), 899 - 905 (2019) [10.1107/S160057751900345X]   Wavefront-propagation simulations have been performed to complete the design of a monochromator beamline for FLASH2, the variable-gap undulator line at the soft X-ray free-electron laser in Hamburg (FLASH). Prior to propagation through the beamline optical elements, the parameters of the photon source were generated using the GENESIS code which includes the free-electron laser experimental data. [...] OpenAccess: PDF PDF (PDFA); Restricted: PDF PDF (PDFA); 2019-07-0916:41 [PUBDB-2019-02677] Journal Article et al Mapping ultrafast ionization of atoms and clusters with terahertz-streaking delay Physical review / A 99(4), 043423 (2019) [10.1103/PhysRevA.99.043423]   We apply THz-field streaking to temporally resolve the ultrafast ionization of neutral cluster vs atomic targets exposed to intense ultrashort soft x-ray pulses from a free-electron laser (FEL). In the experiment pristine Xe and mixed Xe/Ar clusters as well as Xe atoms are ionized in the vicinity of the $4d→ɛf$ giant resonance of Xe [...] OpenAccess: PDF PDF (PDFA); 2019-07-0916:35 [PUBDB-2019-02676] Journal Article et al Electronic decay of core-excited HCl molecules probed by THz streaking Structural dynamics 6(3), 034301 (2019) [10.1063/1.5091756]   The ultrafast electronic decay of HCl molecules in the time domain after resonant core excitation was measured. Here, a Cl-2p core electron was promoted to the antibonding σ* orbital initiating molecular dissociation, and simultaneously, the electronic excitation relaxes via an Auger decay [...] OpenAccess: PDF PDF (PDFA); 2019-06-2111:31 [PUBDB-2019-02530] Journal Article et al Ultrafast charge redistribution in small iodine containing molecules New journal of physics 21(3), 033017 (2019) [10.1088/1367-2630/ab1056]   We present studies on intra-molecular charge redistribution in iodine containing molecules upon iodine-4d photoionization. For this, we employed an XUV-pump-XUV-probe scheme based on time-delayed femtosecond pulses delivered by the free-electron laser at DESY in Hamburg (FLASH) [...] OpenAccess: PDF PDF (PDFA); 2019-05-2911:54 [PUBDB-2019-02388] Journal Article et al An X-ray gas monitor for free-electron lasers Journal of synchrotron radiation 26(4), 1092 - 1100 (2019) [10.1107/S1600577519005174]   A novel X-ray gas monitor (XGM) has been developed which allows the measurement of absolute photon pulse energy and photon beam position at all existing and upcoming free-electron lasers (FELs) over a broad spectral range covering vacuum ultraviolet (VUV), extreme ultraviolet (EUV) and soft and hard X-rays. The XGM covers a wide dynamic range from spontaneous undulator radiation to FEL radiation and provides a temporal resolution of better than 200 ns [...] OpenAccess: PDF PDF (PDFA); 2019-05-0809:15 [PUBDB-2019-02178] Journal Article et al Photon diagnostics at the FLASH THz beamline Journal of synchrotron radiation 26(3), 700 - 707 (2019) [10.1107/S1600577519003412]   The THz beamline at FLASH, DESY, provides both tunable (1–300 THz) narrow-bandwidth (∼10%) and broad-bandwidth intense (up to 150 uJ) THz pulses delivered in 1 MHz bursts and naturally synchronized with free-electron laser X-ray pulses. Combination of these pulses, along with the auxiliary NIR and VIS ultrashort lasers, supports a plethora of dynamic investigations in physics, material science and biology. [...] OpenAccess: PDF PDF (PDFA); 2019-02-2017:27 [PUBDB-2019-01185] Journal Article et al Terahertz-Field-Induced Time Shifts in Atomic Photoemission Physical review letters 122(7), 073001 (2019) [10.1103/PhysRevLett.122.073001]   Time delays for atomic photoemission obtained in streaking or reconstruction of attosecond bursts by interference of two-photon transitions experiments originate from a combination of the quantum mechanical Wigner time and the Coulomb-laser coupling. While the former was investigated intensively theoretically as well as experimentally, the latter attracted less interest in experiments and has mostly been subject to calculations [...] OpenAccess: PDF PDF (PDFA);