Perspective: Opportunities for ultrafast science at SwissFEL

Beaud, P.; Bokhoven, Jeroen A. van; Chergui, Majed; Feurer, Thomas; Haase, Johannes; Ingold, G.; Johnson, S. L.; Knopp, G.; Lemke, Henrik T.; Milne, Christopher J.; Pedrini, Bill; Radi, P. P.; Schertler, Gebhard F. X.; Standfuss, Jörg; Staub, U.; Patthey, L.

doi:10.1063/1.4997222

Cited by 51 publications

(32 citation statements)

References 265 publications

(178 reference statements)

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“…Numerous exciting opportunities are opened up by this technology, including reconstructing realspace molecular movies via time-resolved diffraction as well as time-domain and broadband X-ray Raman experiments (8,(12)(13)(14)(15)(16). The development of FELs (17)(18)(19)(20) as well as tabletop light sources, such as high-harmonic generation for soft X-rays and laser-driven plasma sources for hard X-rays (21)(22)(23)(24), has permitted the generation of bright ultrashort X-ray pulses (25)(26)(27). This has opened up the possibility of carrying out time-dependent, pump-probe diffraction in which a system is first pumped to an excited state by a visible or UV pulse and is then probed via the diffraction of a second X-ray pulse at varying time delays, allowing the reconstruction of "molecular movies" that visualize the evolving electron density (12-15, 28, 29).…”

mentioning

confidence: 99%

Monitoring molecular nonadiabatic dynamics with femtosecond X-ray diffraction

Bennett

Kowalewski

Rouxel

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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Ultrafast time-resolved X-ray scattering, made possible by free-electron laser sources, provides a wealth of information about electronic and nuclear dynamical processes in molecules. The technique provides stroboscopic snapshots of the time-dependent electronic charge density traditionally used in structure determination and reflects the interplay of elastic and inelastic processes, nonadiabatic dynamics, and electronic populations and coherences. The various contributions to ultrafast off-resonant diffraction from populations and coherences of molecules in crystals, in the gas phase, or from single molecules are surveyed for core-resonant and off-resonant diffraction. Single-molecule [Formula: see text] scaling and two-molecule [Formula: see text] scaling contributions, where N is the number of active molecules, are compared. Simulations are presented for the excited-state nonadiabatic dynamics of the electron harpooning at the avoided crossing in NaF. We show how a class of multiple diffraction signals from a single molecule can reveal charge-density fluctuations through multidimensional correlation functions of the charge density.

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mentioning

confidence: 99%

Monitoring molecular nonadiabatic dynamics with femtosecond X-ray diffraction

Bennett

Kowalewski

Rouxel

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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“…One of many reasons for that, and arguably the main one, was the significantly higher energy spread in the POHANG FEL, e ' 1.8 Â 10 À4 to 5 Â 10 À4 (Kang et al, 2017), than that in the LCLS FEL; the weak condition for the Pierce parameter, > 2 e , was hardly fulfilled for the fundamental tone; for high harmonics the inequality was not fulfilled: < e . Another installation, SWISS FEL (Milne et al, 2017), has very low absolute energy spread, 350 keV, which translates into e = 0.006% for the energy E = 5.8 GeV. The harmonic power evolution is shown in Fig.…”

Section: Radiation From Multi-harmonic Undulatorsmentioning

confidence: 99%

“…1 = k=ð ffiffi ffi 2 p Þ, for the PAL-XFEL than for the LCLS line, and the estimate of the spectral width is similar, Á/ ' 0.1%. The split of the fundamental spectrum line at SWISS XFEL (Milne et al, 2017) at = 0.1 nm, where the beam has the same transversal size x,y ' 25 mm, is shown in Fig. 6(a).…”

Section: Research Papers Figurementioning

confidence: 99%

Theoretical spectral analysis of FEL radiation from multi-harmonic undulators

Zhukovsky

2020

J Synchrotron Radiat

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A theoretical study of the spontaneous and stimulated undulator radiation (UR) from electrons in undulators with multiple periods in both transversal directions is presented. Exact expressions are derived for the UR intensities in terms of the generalized Bessel and Airy functions, accounting for undulator field harmonics of arbitrary strength and for real parameters of the beams and installations. Theoretical results are verified with numerical and experimental data for SWISS-XFEL, PAL-XFEL, LEUTL, LCLS etc. The spectrum, UR line shape and width, and the harmonic evolution along the undulators are analyzed and compared with the available data for these experiments. Moreover, the effect of the field harmonics is elucidated. It is demonstrated that the third field harmonic can cause distinct odd UR harmonics. The asymmetric undulator field configuration is identified, which allows intense radiation of these harmonics. The power evolution in a free-electron laser (FEL) with such an undulator is studied by means of an analytical FEL model. The latter is enhanced by a true description of the gradual power saturation of harmonics. A FEL with elliptic undulator and electron–photon phase-shifting is proposed and modeled. It is shown that the resulting harmonic power from the phase-shifted elliptic undulator can be significantly higher than from a planar undulator with the same phase-shifting.

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“…X-ray free-electron lasers provide a powerful tool for investigating fundamental structures and dynamics of materials in physics, chemistry, and biology [1][2][3][4][5]. One significant advantage of X-rays from free-electron lasers is the ability to create pulses with a very short duration compared to typical picosecond-duration pulses from third-generation synchrotron radiation sources.…”

Section: Introductionmentioning

confidence: 99%

Optical second harmonic generation in LiB₃O₅ modulated by intense femtosecond X-ray pulses

Deng¹,

Zerdane²,

Xie³

et al. 2020

Opt. Express

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Many of the scientific applications for X-ray free-electron lasers seek to exploit the ultrashort pulse durations of intense X-rays to obtain femtosecond time resolution of various processes in a "pump-probe" scheme. One of the limiting factors for such experiments is the timing jitter between the X-rays and ultrashort pulses from more conventional lasers operating at near-optical wavelengths. In this work, we investigate the potential of using X-ray-induced changes in the optical second harmonic generation efficiency of a nonlinear crystal to retrieve single-shot arrival times of X-ray pulses with respect to optical laser pulses. Our experimental results and simulations show changes to the efficiency of the second harmonic generation of 12%, approximately three times larger than the measured changes in the transmission of the 800 nm center-wavelength fundamental pulse. Further experiments showing even larger changes in the transmission of 400 nm center-wavelength pulses show that the mechanism of the second harmonic generation efficiency modulation is mainly the result of X-ray-induced changes in the linear absorption coefficients near 400 nm. We demonstrate and characterize a cross-correlation tool based on this effect in reference to a previously demonstrated method of X-ray/optical cross-correlation.

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Perspective: Opportunities for ultrafast science at SwissFEL

Cited by 51 publications

References 265 publications

Monitoring molecular nonadiabatic dynamics with femtosecond X-ray diffraction

Monitoring molecular nonadiabatic dynamics with femtosecond X-ray diffraction

Theoretical spectral analysis of FEL radiation from multi-harmonic undulators

Optical second harmonic generation in LiB₃O₅ modulated by intense femtosecond X-ray pulses

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Perspective: Opportunities for ultrafast science at SwissFEL

Cited by 51 publications

References 265 publications

Monitoring molecular nonadiabatic dynamics with femtosecond X-ray diffraction

Monitoring molecular nonadiabatic dynamics with femtosecond X-ray diffraction

Theoretical spectral analysis of FEL radiation from multi-harmonic undulators

Optical second harmonic generation in LiB3O5 modulated by intense femtosecond X-ray pulses

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Optical second harmonic generation in LiB₃O₅ modulated by intense femtosecond X-ray pulses