# FS-FLASH-O

 2018-01-0513:44 [PUBDB-2018-00199] Journal Article et al Photodissociation of Aligned $\mathrm{CH_3I}$ and $\mathrm{C_{6}H_{3}F_{2}I}$ Molecules Probed with Time-Resolved Coulomb Explosion Imaging by Site-Selective XUV Ionization Structural dynamics 5(1), 014301 - (2018) [10.1063/1.4998648]   We explore time-resolved Coulomb explosion induced by intense, extreme ultraviolet (XUV) femtosecond pulses from a free-electron laser as a method to image photo-induced molecular dynamics in two molecules, iodomethane and 2,6-difluoroiodobenzene. At an excitation wavelength of 267 nm, the dominant reaction pathway in both molecules is neutral dissociation via cleavage of the carbon–iodine bond. [...] Fulltext: PNG; OpenAccess: PDF PDF (PDFA); 2018-01-0316:49 [PUBDB-2018-00094] Journal Article/Contribution to a conference proceedings/Contribution to a book Yurkov, M. Frequency Doubler and Two-Color Mode of Operation at Free Electron Laser FLASH2 Proc. SPIE, 2017. - ISBN - doi:10.1117/12.2265584Advances in X-ray Free-Electron Lasers Instrumentation IV, PraguePrague, Czech Republic, 24 Apr 2017 - 27 Apr 2017 Proceedings of SPIE 10237, 1023710 (2017) [10.1117/12.2265584] special issue: "Advances in X-ray Free-Electron Lasers Instrumentation IV"   We report on the results of the first operation of a frequency doubler at FLASH2. The scheme uses the feature of the variable gap of the undulator. [...] OpenAccess: 1023710 - PDF PDF (PDFA); 10237-35_Yurkov_Doubler-SPIE - PDF PDF (PDFA); 2017-12-2214:02 [PUBDB-2017-14060] Journal Article et al Experimental study of EUV mirror radiation damage resistance under long-term free-electron laser exposures below the single-shot damage threshold Journal of synchrotron radiation 25(1), 77 - 84 (2018) [10.1107/S1600577517017362]   The durability of grazing- and normal-incidence optical coatings has been experimentally assessed under free-electron laser irradiation at various numbers of pulses up to 16 million shots and various fluence levels below 10% of the single-shot damage threshold. The experiment was performed at FLASH, the Free-electron LASer in Hamburg, using 13.5 nm extreme UV (EUV) radiation with 100 fs pulse duration. [...] OpenAccess: PDF PDF (PDFA); 2017-12-2015:10 [PUBDB-2017-13877] Journal Article et al Observation of Reverse Saturable Absorption of an X-ray Laser Physical review letters 119(7), 075002 (2017) [10.1103/PhysRevLett.119.075002]   A nonlinear absorber in which the excited state absorption is larger than the ground state can undergo a process called reverse saturable absorption. It is a well-known phenomenon in laser physics in the optical regime, but is more difficult to generate in the x-ray regime, where fast nonradiative core electron transitions typically dominate the population kinetics during light matter interactions [...] OpenAccess: PDF PDF (PDFA); 2017-12-1911:10 [PUBDB-2017-13688] Journal Article/Contribution to a conference proceedings/Contribution to a book et al A soft x-ray split-and-delay unit for FLASH II : [Proceedings] - , 2017. - doi:10.1117/12.2265708Advances in X-ray Free-Electron Lasers Instrumentation IV, PraguePrague, Czech Republic, 24 Apr 2017 - 27 Apr 2017 Proceedings of SPIE 10237, 1023712 (2017) [10.1117/12.2265708]   For the soft x-ray free-electron laser FLASH II at DESY in Hamburg a new split-and-delay unit (SDU) is built for photon energies in the range of 30 eV < hν < 1500 eV with an option to expand this range to hν = 2500 eV. The SDU is based on wavefront beam splitting at grazing incidence angles. [...] OpenAccess: PDF PDF (PDFA); 2017-12-1818:46 [PUBDB-2017-13675] Journal Article et al Non-invasive online wavelength measurements at FLASH2 and present benchmark Journal of synchrotron radiation 25(1), 3 - 15 (2018) [10.1107/S1600577517013893] special issue: "PhotonDiag2017 Workshop special issue"   At FLASH2, the free-electron laser radiation wavelength is routinely measured by an online spectrometer based on photoionization of gas targets. Photoelectrons are detected with time-of-flight spectrometers and the wavelength is determined by means of well known binding energies of the target species. [...] OpenAccess: PDF PDF (PDFA); 2017-12-1811:00 [PUBDB-2017-13615] Contribution to a conference proceedings et al Status of the Soft X-Ray Free Electron Laser FLASH 8th International Particle Accelerator Conference, IPAC2017, CopenhagenCopenhagen, Denmark, 14 May 2017 - 19 May 2017 JACoW, Geneva, Switzerland , 3 pp. (2017) [10.18429/JACoW-IPAC2017-WEPAB025]   The superconducting free-electron laser user facility FLASH at DESY in Hamburg, routinely produces several thousand photon pulses per second. The operational parameters cover a wavelength range from 90 nm down to 4 nm with pulse energies from several $\mu$J up to 1 mJ and with pulse durations of several hundred fs down to a few fs. [...] OpenAccess: PDF PDF (PDFA); External link: Fulltext 2017-12-1810:52 [PUBDB-2017-13612] Poster et al Status of the Soft X-Ray Free Electron Laser FLASH 8th International Particle Accelerator Conference, IPAC2017, CopenhagenCopenhagen, Denmark, 14 May 2017 - 19 May 2017   The superconducting free-electron laser user facility FLASH at DESY in Hamburg, routinely produces several thousand photon pulses per second. The operational parameters cover a wavelength range from 90 nm down to 4 nm with pulse energies from several $\mu$J up to 1 mJ and with pulse durations of several hundred fs down to a few fs. [...] OpenAccess: PDF PDF (PDFA); 2017-12-0714:09 [PUBDB-2017-12877] Journal Article/Contribution to a conference proceedings/Contribution to a book et al Grating monochromator with ultrafast response for FLASH2 at DESY [Proceedings] - , 2017. - ISBN - doi:10.1117/12.2264885Advances in X-ray Free-Electron Lasers Instrumentation IV, PraguePrague, Czech Republic, 24 Apr 2017 - 27 Apr 2017 Proceedings of SPIE 10237, 1023716 (2017) [10.1117/12.2264885]   We discuss the design of grating-based monochromators for coherent ultrafast pulses in the extreme-ultraviolet. The main application of such instruments is the monochromatization of ultrafast high-order laser harmonics and freeelectron-laser pulses. [...] OpenAccess: PDF PDF (PDFA); 2017-12-0714:06 [PUBDB-2017-12875] Journal Article/Contribution to a conference proceedings/Contribution to a book et al Time-delay-compensated grating monochromator for FEL beamlines : [Proceedings] - , 2014. - doi:10.1117/12.2065257X-Ray Free-Electron Lasers: Beam Diagnostics, Beamline Instrumentation, and Applications II, San DiegoSan Diego, California, 18 Aug 2014 - 19 Aug 2014 Proceedings of SPIE 9210, 921001 (2014) [10.1117/12.2065257]   We present the design of a time-delay-compensated monochromator explicitly designed for extreme-ultraviolet FEL sources, in particular the upcoming FLASH II at DESY (Hamburg). The design originates from the variable-line-spaced (VLS) grating monochromator by adding a second grating to compensate for the pulse-front tilt given by the first grating after the diffraction. [...] OpenAccess: PDF PDF (PDFA);