Chair: Anthony Starace, The University of Nebraska, Lincoln, USA

#73, 8:30 – 9:00 Ultrafast molecular structure determination from aligned polyatomic molecules using laser-induced electron diffraction, M. G. PULLEN, B. WOLTER, A.-T. LE, M. BAUDISCH, M. HEMMER, A. SENFTLEBEN, M. SCLAFANI, C. D. SCHRÖTER, J. ULLRICH, R. MOSHAMMER, C.-D. LIN, AND J. BIEGERT, Laser-induced electron diffraction is a developing dynamical imaging technique that can probe molecular dynamics at fewfemtosecond temporal resolutions and has the potential to reach the sub-femtosecond level. We have developed the recipe to extend the technique to polyatomic molecules and we demonstrate the method by extracting the structure of aligned and anti-aligned acetylene (C2H2). We show that multiple bond lengths can be simultaneously imaged at high accuracy including elusive hydrogen containing bonds. Our results open the door to the investigation of larger complex molecules and the realization of a true molecular movie.

#74, 9:00 – 9:15 Carrier-Envelope Phase Mapping of Laser-Induced Electron Rescattering, HENNING GEISELER, NOBUHISA ISHII, FLORIAN GEIER, KEISUKE KANESHIMA, TERUTO KANAI, AND JIRO ITATANI, We present an experimental technique to probe the energy-dependence of elastic scattering cross sections for electron-ion collisions in laser-induced electron rescattering. When high-energy photoelectrons are produced through ionization in intense few-cycle IR pulses, rescattered electrons originating from a single half-cycle under the rapidly varying pulse envelope are spectrally isolated. Through CEP-control, the scattering energy is scanned over an extended interval, and assisted by a theoretical description, the scattering cross section is extracted. The technique is demonstrated for the case of xenon, revealing a localized enhancement at 17 eV.

#75, 9:15 – 9:30 Retrieval of two-dimensional molecular structure with laser-induced electron diffraction from laser-aligned polyatomic molecules, CHAO YU, HUI WEI, XU WANG, ANH-THU LE, RUIFENG LU, AND C. D. LIN, Imaging the transient process of molecules has been a basic way to investigate chemical reactions and dynamics. Based on laser-induced electron diffraction with partially 1D-aligned molecules, here we provide two efficient methods for reconstructing 2D structure of polyatomic molecules. We demonstrate that electron diffraction images in both scattering angles and broadband energy can be utilized to retrieve complementary structure information, including positions of light atoms. With picometer spatial resolution and the inherent femtosecond temporal resolution of lasers, laser-induced electron diffraction method offers significant opportunities for probing atomic motion in large molecules in a typical pump-probe measurement.

#76, 9:30 – 9:45 Atomic-scale diffractive imaging of subcycle electron dynamics in graphene, V. S. YAKOVLEV, M. I. STOCKMAN, F. KRAUSZ, AND P. BAUM, Using graphene as an example material, we show with simulations that ultrafast electron and X-ray diffraction can provide a time-dependent record of charge-density maps in condensed matter. Such real-space measurements promise subcycle and sub-atomic resolutions, and they can reveal light-driven electron  dynamics that are not easily accessible by conventional spectroscopic methods.

#77 9:45 – 10:00, Resolving tunneling dynamics in attosecond electron holography, G. PORAT, G. ALON, M. KRÜGER, B. D. BRUNER, N. DUDOVICH, Attosecond and strong-field physics offer new insights into ultrafast quantum phenomena, the most fundamental of which is quantum tunneling. We apply attosecond electron holography as a new mechanism to resolve the tunneling dynamics. By adding a weak second harmonic field we map the dynamical properties of the hologram. Specifically, we show that the holographic measurement serves as a differential measurement resolving, with extremely high sensitivity, subtle differences in the ionization times associated with the different electron trajectories.