2019, Ueda, Kiyoshi, Sokell, Emma, Schippers, Stefan, Aumayr, Friedrich, Sadeghpour, Hossein, Burgdörfer, Joachim, Lemell, Christoph, Tong, Xiao-Min, Pfeifer, Thomas, Calegari, Francesca, Palacios, Alicia, Martin, Fernando, Corkum, Paul, Sansone, Giuseppe, Gryzlova, Elena V., Grum-Grzhimailo, Alexei N., Piancastelli, Maria Novella, Weber, Peter M., Steinle, Tobias, Amini, Kasra, Biegert, Jens, Berrah, Nora, Kukk, Edwin, Santra, Robin, Müller, Alfred, Dowek, Danielle, Lucchese, Robert R., McCurdy, C. William, Bolognesi, Paola, Avaldi, Lorenzo, Jahnke, Till, Schöffler, Markus S., Dörner, Reinhard, Mairesse, Yann, Nahon, Laurent, Smirnova, Olga, Schlathölter, Thomas, Campbell, Eleanor E.B., Rost, Jan-Michael, Meyer, Michael, Tanaka, Kazuo A.

We publish three Roadmaps on photonic, electronic and atomic collision physics in order to celebrate the 60th anniversary of the ICPEAC conference. In Roadmap I, we focus on the light-matter interaction. In this area, studies of ultrafast electronic and molecular dynamics have been rapidly growing, with the advent of new light sources such as attosecond lasers and x-ray free electron lasers. In parallel, experiments with established synchrotron radiation sources and femtosecond lasers using cutting-edge detection schemes are revealing new scientific insights that have never been exploited. Relevant theories are also being rapidly developed. Target samples for photon-impact experiments are expanding from atoms and small molecules to complex systems such as biomolecules, fullerene, clusters and solids. This Roadmap aims to look back along the road, explaining the development of these fields, and look forward, collecting contributions from twenty leading groups from the field. © 2019 IOP Publishing Ltd.

2017-04-10, Savelyev, Evgeny, Boll, Rebecca, Bomme, Cédric, Schirmel, Nora, Redlin, Harald, Erk, Benjamin, Düsterer, Stefan, Müller, Erland, Höppner, Hauke, Toleikis, Sven, Müller, Jost, Kristin Czwalinna, Marie, Treusch, Rolf, Kierspel, Thomas, Mullins, Terence, Trippel, Sebastian, Wiese, Joss, Küpper, Jochen, Brauβe, Felix, Krecinic, Faruk, Rouzée, Arnaud, Rudawski, Piotr, Johnsson, Per, Amini, Kasra, Lauer, Alexandra, Burt, Michael, Brouard, Mark, Christensen, Lauge, Thøgersen, Jan, Stapelfeldt, Henrik, Berrah, Nora, Müller, Maria, Ulmer, Anatoli, Techert, Simone, Rudenko, Artem, Rolles, Daniel

In pump-probe experiments employing a free-electron laser (FEL) in combination with a synchronized optical femtosecond laser, the arrival-time jitter between the FEL pulse and the optical laser pulse often severely limits the temporal resolution that can be achieved. Here, we present a pump-probe experiment on the UV-induced dissociation of 2,6-difluoroiodobenzene (C6H3F2I) molecules performed at the FLASH FEL that takes advantage of recent upgrades of the FLASH timing and synchronization system to obtain high-quality data that are not limited by the FEL arrival-time jitter. We discuss in detail the necessary data analysis steps and describe the origin of the time-dependent effects in the yields and kinetic energies of the fragment ions that we observe in the experiment.

2018, Amini, Kasra, Savelyev, Evgeny, Brauße, Felix, Berrah, Nora, Bomme, Cédric, Brouard, Mark, Burt, Michael, Christensen, Lauge, Düsterer, Stefan, Erk, Benjamin, Höppner, Hauke, Kierspel, Thomas, Krecinic, Faruk, Lauer, Alexandra, Lee, Jason W. L., Müller, Maria, Müller, Erland, Mullins, Terence, Redlin, Harald, Schirmel, Nora, Thøgersen, Jan, Techert, Simone, Toleikis, Sven, Treusch, Rolf, Trippel, Sebastian, Ulmer, Anatoli, Vallance, Claire, Wiese, Joss, Johnsson, Per, Küpper, Jochen, Rudenko, Artem, Rouzée, Arnaud, Stapelfeldt, Henrik, Rolles, Daniel, Boll, Rebecca

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. This allows investigating the influence of the molecular environment on the absorption of an intense, femtosecond XUV pulse and the subsequent Coulomb explosion process. We find that the XUV probe pulse induces local inner-shell ionization of atomic iodine in dissociating iodomethane, in contrast to non-selective ionization of all photofragments in difluoroiodobenzene. The results reveal evidence of electron transfer from methyl and phenyl moieties to a multiply charged iodine ion. In addition, indications for ultrafast charge rearrangement on the phenyl radical are found, suggesting that time-resolved Coulomb explosion imaging is sensitive to the localization of charge in extended molecules.