Browsing by Author "Frühling, Ulrike"
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- ItemCorrelated electronic decay in expanding clusters triggered by intense XUV pulses from a Free-Electron-Laser(London : Nature Publishing Group, 2017) Oelze, Tim; Schütte, Bernd; Müller, Maria; Müller, Jan P.; Wieland, Marek; Frühling, Ulrike; Drescher, Markus; Al-Shemmary, Alaa; Golz, Torsten; Stojanovic, Nikola; Krikunova, MariaIrradiation of nanoscale clusters and large molecules with intense laser pulses transforms them into highly-excited non- equilibrium states. The dynamics of intense laser-cluster interaction is encoded in electron kinetic energy spectra, which contain signatures of direct photoelectron emission as well as emission of thermalized nanoplasma electrons. In this work we report on a so far not observed spectrally narrow bound state signature in the electron kinetic energy spectra from mixed Xe core - Ar shell clusters ionized by intense extreme-ultraviolet (XUV) pulses from a free-electron-laser. This signature is attributed to the correlated electronic decay (CED) process, in which an excited atom relaxes and the excess energy is used to ionize the same or another excited atom or a nanoplasma electron. By applying the terahertz field streaking principle we demonstrate that CED-electrons are emitted at least a few picoseconds after the ionizing XUV pulse has ended. Following the recent finding of CED in clusters ionized by intense near-infrared laser pulses, our observation of CED in the XUV range suggests that this process is of general relevance for the relaxation dynamics in laser produced nanoplasmas.
- ItemTHz streak camera performance for single-shot characterization of XUV pulses with complex temporal structures(Washington, DC : Soc., 2020) Oelze, Tim; Kulyk, Olena; Schütte, Bernd; Frühling, Ulrike; Klimešová, Eva; Jagielski, Bartholomäus; Dittrich, Laura; Drescher, Markus; Pan, Rui; Stojanovic, Nikola; Polovinkin, Vitaly; Khakurel, Krishna P.; Muehlig, Kerstin; Bermudez Macias, Ivette J.; Düsterer, Stefan; Faatz, Bart; Andreasson, Jakob; Wieland, Marek; Krikunova, MariaThe THz-field-driven streak camera has proven to be a powerful diagnostic-technique that enables the shot-to-shot characterization of the duration and the arrival time jitter of free electron laser (FEL) pulses. Here we investigate the performance of three computational approaches capable to determine the duration of FEL pulses with complex temporal structures from single-shot measurements of up to three simultaneously recorded spectra. We use numerically simulated FEL pulses in order to validate the accuracy of the pulse length retrieval in average as well as in a single-shot mode. We discuss requirements for the THz field strength in order to achieve reliable results and compare our numerical study with the analysis of experimental data that were obtained at the FEL in Hamburg - FLASH. © 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement