Tunable isolated attosecond X-ray pulses with gigawatt peak power from a free-electron laser

Abstract

The quantum mechanical motion of electrons in molecules and solids occurs on the sub-femtosecond timescale. Consequently, the study of ultrafast electronic phenomena requires the generation of laser pulses shorter than 1 fs and of sufficient intensity to interact with their target with high probability.Probing these dynamics with atomic-site specificity requires the extension of sub-femtosecond pulses to the soft X-ray spectral region. Here we report the generation of isolated GW-scale soft X-ray attosecond pulses with an X-ray free-electron laser. Our source has a pulse energy that is six orders of magnitude larger than any other source of isolated attosecond pulses in the soft X-ray spectral region, with a peak power in the tens of gigawatts. This unique combination of high intensity, high photon energy and short pulse duration enables the investigation of electron dynamics with X-ray non-linear spectroscopy and single-particle imaging.their assistance in designing, constructing and installing the XLEAP wiggler. We also acknowledge the SLAC Accelerator Operations group, and the Mechanical and Electrical engineering divisions of the SLAC Accelerator Directorate, especially

Collinear setup for delay control in two-color attosecond measurements

“…Ultrashort laser sources are unique technological tools to resolve in time laser-matter dynamics on ultrafast timescales [1]. Nowadays, the highest temporal resolution of pump-probe experiments lies in the attosecond (1 as = 10 −18 s) domain and it is provided by the availability of ultrashort extreme ultraviolet (XUV) and x-ray pulses delivered either by high-order harmonic generation (HHG) in gases [2][3][4] or by Free-Electron Lasers [5,6]. HHG-based XUV attosecond pulses are routinely used in time-resolved pump-probe spectroscopic techniques to initiate dynamics, which are then probed by a second pulse at a later time.…”

Towards an ultra-compact x-ray free-electron laser (Conference Presentation)

“…This opens new possibilities in experiments involving coherent x-rays and IR light as both pump and probe [105] well beyond the capabilities of high harmonic generation sources [28]. With such sub-cycle synchronization, one may be able to obtain dynamical information with unprecedented resolution, as recently demonstrated in the XLEAP experiment at SLAC [106], which was also a first test of the ESASE scheme for XFEL use. Further, the compactness of the XFEL and the high gain predicted from the presented UC-XFEL approach may enable a new frontier in recirculating FEL systems such as regenerative amplifiers.…”

“…This is accompanied by a renewed emphasis on the ESASE analysis of the second compressor, where by taking into account finite-laser spot size effects, one may increase the brightness of the electron beam micro-bunches, at a cost of some efficiency in the bunching process. Advanced work on the ESASE technique is being applied to exploratory research on MaRIE-class XFELs; the current work here also has potential impact on XLEAP-like scenarios for existing XFELs [106]. Finally, we note that optically bunched high-peakcurrent beams may be effectively used to excite TV/m-amplitude wakefield acceleration waves in plasma [149].…”

Attosecond transient absorption spooktroscopy: a ghost imaging approach to ultrafast absorption spectroscopy

“…The spatial localization of the core orbitals means excitation of electrons from these orbitals to valence electronic states provides an atomic-site specific probe of transient valence electronic structure. The recent demonstration of isolated attosecond pulses from an X-ray free-electron laser (XFEL), with photon energies tunable across the soft X-ray regime and spectral brightness six orders of magnitude greater than HHG sources [20], enables numerous previously unfeasible attosecond measurements. However, the implementation of ATAS with an attosecond XFEL source presents a number of challenges.…”

“…The tunability and unprecedented brightness of XFEL sources provides a powerful tool for the experimental investigation of ultrafast molecular dynamics [19]. Recently, GW-scale soft X-ray isolated attosecond pulses (IAPs) were demonstrated at the Linac Coherent Light Source (LCLS), using an implementation of the enhanced self amplified spontaneous emission (ESASE) technique [20]. The spectral brightness of this attosecond source is six orders of magnitude greater than any tabletop HHG-based source of IAPs, facilitating non-linear spectroscopies.…”