Aarhus University Seal

Speaker Abstracts Tuesday 25th June

Tuesday 25th June 2013

   
 Chair: Henrik Stapelfeldt
09:00-10:00 PT: Atomic Physics with Attosecond Pulses 
 Anne L'Huillier (Lund University) 
  When atoms are exposed to intense laser radiation, electrons in the ground state may tunnel ionize, acquire energy from the field, and recombine, leading to the generation of attosecond pulses with broad bandwidth. When this process is repeated many times, the emitted radiation takes the form of a frequency comb, with peaks at odd harmonics of the laser field. This presentation will review the techniques used to optimize and characterize the radiation. The short pulse duration and broad bandwidth of attosecond pulses allow us to measure the phase and amplitude of an electronic wave packet using interferometric techniques. This gives us access to the temporal dynamics of the process that led to this wave-packet. We will describe some of these applications, and in particular recent results concerning photoionization dynamics.
   
 
   Session 3a: T8 Ultrafast dynamics and attosecond physics 
 Chair: Roland Wester
10:30-11:00 IT: Clocking ultrafast molecular dynamics through laser induced interference effects 
 Henri Bachau (Université Bordeaux 1) 
  We study the dissociation of H2+ and the dissociative ionization of H2 in UV femtosecond laser fields. We investigate two-UV-photon absorption and UV-pump-UV-probe schemes to trace the evolution of nuclear wave packets at the femtosecond timescale. Within these contexts the contribution of the 2psu dissociative channel (for H2+) and 2psu ionization channel (for H2) results in interferences leading to modulations of the proton kinetic energy and to asymmetries in the electron angular distributions. Recent results will be reported.
11:00-11:30 IT: Electron dynamics in the deep tunneling regime 
 Jens Biegert (Institute of Photonic Sciences, Barcelona) 
  We present the first 3D momentum measurements of mid-IR tunneling-ionization dynamics of atoms and molecules. Scrutinising such dynamics is important for realising future possibilities in mid-IR recollision physics and we achieve high precision measurements at only 1 meV above the threshold despite ponderomotive energies 5 orders of magnitude higher. We show first 3D momentum distributions demonstrating surprising new observations of near-zero momentum electrons and low momentum structures, below the eV, despite quiver energies of 95 eV.
11:30-12:00 IT: Correlated electron dynamics on the attosecond scale 
 Johannes Feist (Universidad Autonoma de Madrid) 
  Attosecond light pulses present novel tools for investigating electronic processes on their natural time scale. Of particular interest is the access to and control of correlated multi-electron dynamics. I will discuss recent progress in their understanding for setups such as attosecond streaking, based on large-scale solutions of the multi-electron Schrödinger equation.
12:00-12:30 IT: Electronic rescattering dynamics in laser fields 
 Stefanie Gräfe (Vienna University of Technology) 
   
   
 
   Session 3b: T13 Clusters and nanoparticles 
 Chair: Bernd Huber
10:30-11:00 IT: Electronic properties and many-body effects in epitaxial graphene 
 Philip Hofmann (Aarhus University) 
  High-quality, large-area epitaxial graphene can be grown on metal surfaces and this has been used to study the fundamental electronic structure and many-body effects in graphene. However, while the metal-graphene interaction is weak, it can still have a non-negligible effect on the properties of the graphene layer. In this talk, I will review the basic electronic properties of epitaxial graphene and discuss, how the graphene-substrate interaction can be modified by intercalation. It is even possible to step-wise intercalate a layer of SiO2 under the graphene, such that it becomes totally insulated from the metallic substrate. This opens the possibility of electrical transport measurements through the epitaxial graphene - something that is otherwise not possible because of the dominating transport through the underlying metal.
11:00-11:30 IT: Vibrational spectroscopy of metal cluster complexes: investigating the chemistry on a small surface 
 Andre Fielicke (Fritz Haber Institute of the Max Planck Society) 
  The application of IR Free Electron Lasers in gas-phase molecular spectroscopy opens up new possibilities in the structural characterization of elusive species, like metal clusters. The structures of bare metal clusters can be determined from their far-IR spectra, while the activation and reactions of cluster-bound ligands are probed by characteristic modes in the mid-IR.
11:30-12:00 IT: Superatoms and viruses 
 Hannu Häkkinen (University of Jyväskylä) 
  The electronic structure of gold and silver nanoclusters stabilized by organic ligands can be understood from the superatom model that accounts for the delocalized “metallic” electrons in the metal core. Recent progress in understanding these systems is reviewed and their bio-conjugation to enteroviruses is discussed.
12:00-12:30 IT: Spectroscopy of water surfaces 
 Niklas Ottosson (FOM Institute AMOLF) 
 

Due to its variable surface sensitivity and elemental specificity, core-level X-ray photoelectron spectroscopy (XPS) is an ideal technique to investigate the surface affinity and chemical state of a wide variety of compounds in the condensed phase. While the vacuum requirements of XPS long hampered the possibility to measure volatile liquid samples, the development of the liquid micro-jet technique has recently enabled measurements of photoelectron spectra from aqueous samples. In this talk I will present a series of recent liquid-jet XPS studies of hydrated organic molecules and ions (e.g. small linear carboxylic acids, benzoic acid, and simple alkali halide salts), which display rich and sometimes somewhat unexpected surface behaviors. Special emphasis is put on connections to and implications for fundamental atmospheric chemistry.

   
 
12:30-15:00 Poster session 
 
   
 
   Session 4a: T2 Atomic and molecular collisions / T13 Clusters and nanoparticles 
 Chair: Preben Hvelplund
15:30-16:00 IT: Experimental investigations of thermodynamical properties of small molecules and clusters 
 Yoni Toker (Weizmann Institute of Science) 
  Statistical dissociation is a perplexing process in which following photon absorption molecules and clusters dissociate on very long time-scales ranging up to hundreds of microseconds. As this process is statistical in nature it can be used as a tool for investigating the thermodyanmic properties of even very small systems. We will show how black-body induced radiative dissociation can be used to infer the binding energies of SF6 based clusters, how delayed electron emission can be used to study radiative cooling of Al4-, and how statistical framentation can be used to determine the heat capacity of the retinal chromophore.
16:00-16:30 IT: Ions colliding with clusters and biomolecules 
 Henrik Cederquist (Stockholm University) 
  In this talk I will present results on collisions between atomic ions, or atoms, and biomolecules, polycyclic aromatic hydrocarbons (PAHs), fullerenes, and clusters of such species. I will show that non-statistical fragmentation dominates when slow PAHs collide with He and that covalent dumb-bell C119+ forms when He collides with van der Waals clusters of C60 molecules.
16:30-17:00 IT: Quantum Effects in Cold Reactive Collisions 
 Edvardas Narevicius (Weizmann Institute of Science) 
   
17:00-17:30 IT: Ion induced fragmentation of complex molecules and clusters of molecules 
 Patrick Rousseau (Centre de Recherche sur les Ions, les Matériaux et la Photonique) 
  Low-energy multiply charged ions are an interesting probe for the study of the physical chemical properties of complex molecular systems. Charge and energy transfers occur during the interaction at the fs timescale. We will illustrate the application of the collisions with low-energy ions in the case of the ionisation/fragmentation of biomolecules.
   
 
   Session 4b: T14 Surface reaction dynamics and self assembly 
 Chair: Klavs Hansen
15:30-16:00 IT: Guiding ions through nanocapillaries 
 Reinhold Schuch (Stockholm University) 
  Charged particles, in particular slow highly charged ions, are found to be guided through nanocapillaries in various insulating materials by self-organized charge patches on the inner walls of the channels. Phenomena, such as time dependent formation of the guiding potential, its temperature dependence, and shaping of ion beams by irregular cross sections of capillaries will be presented.
16:00-16:30 IT: Reactive and non-reactive scattering of diatomic molecules on metal surfaces 
 Cristina Diaz (Universidad Autonoma de Madrid) 
  Understanding the fundamental principles that govern molecular dynamical processes occurring on metal surfaces is a basic requirement to design and develop new and improved catalyzers. Accurate state-of-the-art theoretical simulations are very useful, not only to interpret experimental measurements, but also to predict new trends.
16:30-17:00 IT: Interaction of highly charged ions with surfaces - dissipation of potential energy 
 Stefan Facsko (Helmholtz-zentrum Dresden-Rossendorf) 
  Highly charged ions (HCI) release a large amount of potential energy during their neutralization when interacting with solid surfaces. This energy is mostly retained in the solid leading to local phase transformations on a nanometer scale. The study of these modifications on surfaces or thin foils as a function of potential and kinetic energy gives insight into the interaction of HCIs with surfaces as well as into phase transformations under non-equilibrium conditions.
17:00-17:15 CT: Charge transfer between molecules and metal surfaces covered with ultrathin insulating films 
 Sergio Diaz-Tendero (Universidad Autonoma de Madrid) 
  T14-6-Diaz-Tendero.pdf
17:15-17:30 CT: Composite spontelectric films: nanostructured polarized molecular solids 
 Andrew Cassidy (Aarhus University) 
  T14-11-Cassidy.pdf