2018-8-3, Sauppe, Mario, Rompotis, Dimitrios, Erk, Benjamin, Bari, Sadia, Bischoff, Tobias, Boll, Rebecca, Bomme, Cédric, Bostedt, Christoph, Dörner, Simon, Düsterer, Stefan, Feigl, Torsten, Flückiger, Leonie, Gorkhover, Tais, Kolatzki, Katharina, Langbehn, Bruno, Monserud, Nils, Müller, Erland, Müller, Jan P., Passow, Christopher, Ramm, Daniel, Rolles, Daniel, Schubert, Kaja, Schwob, Lucas, Senfftleben, Björn, Treusch, Rolf, Ulmer, Anatoli, Weigelt, Holger, Zimbalski, Jannis, Zimmermann, Julian, Möller, Thomas, Rupp, Daniela

Extreme ultraviolet (XUV) and X-ray free-electron lasers enable new scientific opportunities. Their ultra-intense coherent femtosecond pulses give unprecedented access to the structure of undepositable nanoscale objects and to transient states of highly excited matter. In order to probe the ultrafast complex light-induced dynamics on the relevant time scales, the multi-purpose end-station CAMP at the free-electron laser FLASH has been complemented by the novel multilayer-mirror-based split-and-delay unit DESC (DElay Stage for CAMP) for time-resolved experiments. XUV double-pulses with delays adjustable from zero femtoseconds up to 650 picoseconds are generated by reflecting under near-normal incidence, exceeding the time range accessible with existing XUV split-and-delay units. Procedures to establish temporal and spatial overlap of the two pulses in CAMP are presented, with emphasis on the optimization of the spatial overlap at long time-delays via time-dependent features, for example in ion spectra of atomic clusters.

2018-8-2, Erk, Benjamin, Müller, Jan P., Bomme, Cédric, Boll, Rebecca, Brenner, Günter, Chapman, Henry N., Correa, Jonathan, Düsterer, Stefan, Dziarzhytski, Siarhei, Eisebitt, Stefan, Graafsma, Heinz, Grunewald, Sören, Gumprecht, Lars, Hartmann, Robert, Hauser, Günter, Keitel, Barbara, von Korff Schmising, Clemens, Kuhlmann, Marion, Manschwetus, Bastian, Mercadier, Laurent, Müller, Erland, Passow, Christopher, Plönjes, Elke, Ramm, Daniel, Rompotis, Dimitrios, Rudenko, Artem, Rupp, Daniela, Sauppe, Mario, Siewert, Frank, Schlosser, Dieter, Strüder, Lothar, Swiderski, Angad, Techert, Simone, Tiedtke, Kai, Tilp, Thomas, Treusch, Rolf, Schlichting, Ilme, Ullrich, Joachim, Moshammer, Robert, Möller, Thomas, Rolles, Daniel

The non-monochromatic beamline BL1 at the FLASH free-electron laser facility at DESY was upgraded with new transport and focusing optics, and a new permanent end-station, CAMP, was installed. This multi-purpose instrument is optimized for electron- and ion-spectroscopy, imaging and pump–probe experiments at free-electron lasers. It can be equipped with various electron- and ion-spectrometers, along with large-area single-photon-counting pnCCD X-ray detectors, thus enabling a wide range of experiments from atomic, molecular, and cluster physics to material and energy science, chemistry and biology. Here, an overview of the layout, the beam transport and focusing capabilities, and the experimental possibilities of this new end-station are presented, as well as results from its commissioning.

2017, Oelze, Tim, Schütte, Bernd, Müller, Maria, Müller, Jan P., Wieland, Marek, Frühling, Ulrike, Drescher, Markus, Al-Shemmary, Alaa, Golz, Torsten, Stojanovic, Nikola, Krikunova, Maria

Irradiation 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.