Wissenschaftliches Programm

Die Länge von angemeldeten Vorträgen beträgt 20 Minuten einschließlich Diskussion.

Poster und Vorträge können folgenden Themengebieten zugeordnet werden:

• Astronomie und Astrophysik
• Atomphysik
• Molekülphysik
• Biophysik
• Chemische Physik
• Festkörperphysik
• Philosophie
• Kernphysik
• Medizinische Physik
• Nanophysik
• Quantenphysik
• Technische Informatik
• Teilchenphysik
• Theoretische Physik
• Umweltphysik
• Mathematik und Informatik
• außeruniversitäre Arbeitswelten
• Öffentlichkeitsarbeit
• Didaktik
• Gesellschaftswissenschaft
• Sonstiges

Der Eröffnungsvortrag am 03.11.2016 um 16:30 wird gehalten von:

Prof. Dr. Petra Rudolf, University of Groningen, Zernike Institute for Advanced Materials, NL

See atoms move in real time: ultrafast electron diffraction

Time-resolved electron diffraction is a unique tool for providing direct and detailed information on the structural dynamics of solid surfaces, nano-sized materials, molecules and atomically thin layers, thanks to the high cross section for interaction between electron and matter. Femtosecond lasers are used to generate ultrashort light and electron pulses. Light initiates a process in the sample - a phase transition, an electronic excitation or simply a temperature jump - and by recording snapshots of the electrons diffracted from the sample in a stroboscopic fashion, one can image the photo-induced motion of the structure. In this talk I shall try to give a taste of the immense possibilities of ultrafast electron diffraction, illustrating how this novel technique opens the door to physical understanding of many aspects of light-matter interaction such as out of equilibrium structural phase transitions, melting, controlled nanoscale mechanical phenomena, and creation of coherent phonons.

Der Öffentliche Abendvortrag am 04.11.2016 um 18:30 Uhr wird gehalten von:

Prof. Dr. Margarete Mühlleitner, Karlsruher Institut für Technologie (KIT), Institut für Theoretische Physik (ITP)

Gewichtsprobleme in der Teilchenphysik oder wie die Teilchen zu ihrer Masse kommen

Grundlagenforschung in der Teilchenphysik ist angetrieben von unserem tiefen Bedurfnis, die Geheimnisse der Natur zu ergründen. Wir möchten verstehen, wie sich das Universum entwickelte und woraus es besteht. Was sind die Bausteine der Materie und welche Kräfte halten sie zusammen? Das Standardmodell der Teilchenphysik fasst unser heutiges Wissen über die fundamentalen Strukturen der Materie und Kräfte zusammen. Eine drängende Frage ist in diesem Zusammenhang die nach der Erzeugung der Teilchenmassen. Mit der Entdeckung des Higgsbosons durch die LHC Experimente ATLAS und CMS sind wir der Beantwortung dieser Frage ein großes Stück näher gekommen. Was aber steckt hinter der Grundidee des Higgsmechanismus und wie kann diese den Ursprung der Massen erklären? Wie funktioniert das Wechselspiel zwischen theoretischen Ideen und experimenteller Forschung, welches schließlich fast 50 Jahre nach der Postulierung des Higgsteilchens zu seiner Entdeckung fuürte? Welche Auswirkungen hat diese Entdeckung auf unser Verständnis der Natur, wie wird sie unsere weitere Forschung beeinflussen und lenken? In dem Vortrag werden diese und weitere Fragen diskutiert werden.

Weitere Plenarvorträge werden gehalten von:

Prof. Dr. Gudrun Hiller, Technische Universität Dortmund, High Energy & Particle Theory Group

Flavor – Generationsstruktur in der Hochenergiephysik

Eines der faszinierendsten Phänomene der Teilchenphysik ist die Generationsstruktur fundamentaler Materie, also der Quarks und Leptonen. In diesem Vortrag wird erklärt, was die dazugehörigen Quantenzahlen ”Flavors” sind, und was wir über diese wissen. Wir berichten über spannende neue Ergebnisse auf der Suche nach Physik jenseits des Standardmodells in der Flavorphysik.

Dr. Kerstin Tackmann , Deutsches Elektronen-Synchrotron (DESY), ATLAS

Recent results from the ATLAS and CMS experiments at the Large Hadron Collider

The experiments at the Large Hadron Collider (LHC) at CERN in Geneva are using proton-proton collisions at high energy to study the physics of elementary particles and the forces acting between them. After successful operation at center-of-mass energies of 7 and 8 TeV from 2010 to 2012, the LHC has been delivering pp collisions at 13 TeV since summer 2015. I will give an overview of recent results from the ATLAS and CMS experiments, including an overview of the status of measurements of the properties of the Higgs boson, discovered in 2012, and highlights from precision measurements and searches for physics beyond the Standard Model of particle physics.

Prof. Dr. Francesca Calegari, Deutsches Elektronen Synchrotron Physics Department, University of Hamburg, IFN-CNR, Milano

Tracking electron dynamics in molecules with extremely short light pulses

Dynamical processes in molecules occur on an ultrafast temporal scale, ranging from picoseconds (1ps=10-12 s) to femtoseconds (1fs =10-15 s) when concerning with a structural change, down to attoseconds (1as = 10-18 s) when dealing with electrons. Electron dynamics plays a very important role in bond-formation and bond-breakage, thus determining the final chemical reactivity of a molecule. At the most basic level we can assert that chemical reactions are the result of interactions between electrons. Within this context, a prominent question still needs to be addressed: which is the role of the electron dynamics in the photo-induced chemical changes that occur in our own biological molecules? As the question will be addressed for simple biorelevant molecules in a bottom-up approach, the physical origin of a variety of light-driven processes occurring in more complex biological systems of crucial importance in photo-chemistry and photo-biology will be disclosed. In this talk I will present advancements in attosecond technology and the application of these ultrafast light transients for the investigation of the electron dynamics in molecules. I will show that attosecond light pulses can be used to ”watch” in real time charge migration occurring in a few femtoseconds between two different functional groups of aromatic amino acids (the building blocks of proteins). These findings open new important perspectives for the future understanding of the role of the electron dynamics in the photochemistry of bio-relevant molecules.

Prof. Dr. Christiane Koch, Universität Kassel, Theoretische Physik III - Quantendynamik und -kontrolle

Quantum resonances in cold collisions

Collisions between individual atoms and molecules in the gas phase provide the most basic testbed for our understanding of intermolecular interactions. At low collisional energies, quantum effects such as tunneling and resonances dominate the scattering dynamics. Resonances correspond to a quantization of the relative motion; they enable the formation of chemical bonds and are particularly susceptible to external field control. Using the example of cold Penning ionization reactions, I will discuss under which conditions quantum resonances come into play in cold collisions, how they can be probed by external fields, and what they allow us to learn about the intermolecular interactions. Moreover, I will show how active control of scattering resonances modifies the process of bond making at very low temperature and thus provides a key to solution in the long-standing quest to control chemical reactions.

Prof. Dr. Leticia González, Universität Wien, Institut für Theoretische Chemie

Molecular nonadiabatic dynamics including spin transitions

Spin has important theoretical implications and many practical applications across different scientific disciplines. In this presentation, I will discuss about how to model electronic spin transitions in molecular systems subject to light irradiation. We employ ab initio trajectory surface hopping techniques that allow us to include any arbitrary type of coupling. In this way, it is straightforward to study excited state dynamics induced by nonadiabatic effects or by spin-orbit couplings, as well as by laser interactions. As an example, the direct consequences of spin for DNA photostability and photodamage will be explained.

Prof. Dr. Prof. Cristiane Morais Smith, University of Groningen, Zernike Institute for Advanced Materials

Graphene: the good, the bad, the nano and the pseudo

Graphene is probably the most fascinating material ever discovered, but it has some drawbacks: it is not superconducting and it does not exhibit the quantum spin Hall effect. The interesting electronic properties of graphene, such as the presence of charge carriers that behave as if they would have no mass, are rooted on the honeycomb lattice of the carbon atoms. A key question in this regard is: if we build a honeycomb lattice of semiconducting nanocrystals, is it going to behave like graphene or like the semiconducting building blocks? In the first part of the talk, I will show that these systems, which have been experimentally synthesized recently [1], combine the best of the two materials. Honeycomb lattices of semiconducting nanocrystals exhibit a gap at zero energy, as well as Dirac cones at finite energies. In addition, a honeycomb lattice made of CdSe nanocrystals displays topological properties in the valence band [2], whereas for HgTe very large topological gaps are predicted to occur in the conduction p-bands [3]. These artificial materials thus open the possibility to engineer higher- orbital physics with Dirac electrons and to realize quantum (spin) Hall phases at room temperature [3]. In the second part of the talk, I will discuss how to describe the full dynamical electromagnetic interaction in 2D systems like graphene, where the electrons are constrained to move in the 2D plane, whereas the photons move in 3D. By using the pseudo-QED approach, I will show how quantized edge states emerge in this system and give rise to the quantum Valley Hall Effect [4], thus opening the possibility to realize Valleytronics as an alternative to Spintronics and Electronics.

[1] M. P. Boneschanscher et al, Science 344, 1377 (2014). [2] E. Kalesaki et al., Phys. Rev. X 4, 011010 (2014). [3] W. Beugeling, E. Kalesaki, C. Delerue, Y.-M. Niquet, D. Vanmaekelbergh, and C. Morais Smith, Nature Communications 6, 6316 (2015). [4] E. Marino, L. O. Nascimento, V. S. Alves, and C. Morais Smith, Phys. Rev. X 5, 011040 (2015).