Physikalisches Kolloquium

Vorträge im SS 2014

Physikalisches Kolloquium der Universität Kiel


Dienstag, 29. Apr. 2014 - Prof. K. Meier, KIP Universität Heidelberg

From Ions to Electrons - Physical Models of Brain Circuits

Dienstag, 06. Mai 2014 - Prof. B. Abel, IOM Leipzig / U Leipzig

Ultrafast spectroscopy near liquid water interfaces employing high-harmonics radiation

Dienstag, 13. Mai 2014 - Frau Dr. Tanja Mehlstäubler, Physik. Techn. Bundesanstalt

Relativistic Geodesy with Optical Clock

Dienstag, 27. Mai 2014 - Dr. Julia Stähler, F.-Haber-Institut Berlin

Ultrafast dynamics of exciton formation at the ZnO (10-10) surface

Dienstag, 03. Jun. 2014 - Prof. G. Brezesinski, MPI Potsdam

Amphilic molecules confined at the air / liquid interface

Montag, 16. Jun. 2014 (Sonderkolloqium) - Dr. Dieter Bilitza, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA und George Mason University, Space Weather Laboratory, Fairfax, Virginia, USA

Die Ionosphäre - Einführung und neueste Ergebnisse

Dienstag, 24. Jun. 2014 - Dr. D. Lundin

Thin film deposition by plasma-based processes

Dienstag, 01. Jul. 2014 - Dr. Birger Buttenschön, Max-Planck-Institut für Plasmaphysik, Greifswald

Plasma Wakefield Acceleration - Ein neues Beschleunigerkonzept zur Erzeugung hochenergetischer Elektronen- und Positronenstrahlen

Dienstag, 08. Jul. 2014 - Dr. Klaus Ellmer, Helmholtz-Zentrum Berlin

Großflächiges Magnetronsputtern von Solarzellen und Wasserspaltungselektroden für zukünftige regenerative Energieversorgung

Vorträge im WS 2016/2017

Kolloquiumsvorträge (dienstags, 12.15 Max-Planck Hörsaal)

  • 18. Oktober

    Bridget Murphy (IEAP)  Murphy.pdf
    When (two) surfaces meet
  • 25. Oktober 2016

    Rodger Thomson (Tucson)  Thompson.pdf
    Testing Dark Energy and New Physics with Fundamental Constants
  • 15. November 2016

    Hanno Kählert (ITAP) Kählert.pdf
    Challenges for theory in strongly coupled (complex) plasmas

  • 13. Dezember 2016

    Alexey Chernikov (Univ. Regensburg)
    Excitons in 2D materials

    Since the discovery of graphene, a single sheet of carbon atoms, research focused on two-dimensional (2D) van der Waals materials evolved rapidly due the availability of atomically thin, thermally stable crystals with intriguing physical properties. The 2D materials naturally inherit major traits associated with systems of reduced dimensionality: strongly enhanced interactions, efficient light-matter coupling, and sensitivity to the environment. In particular, the considerable strength of the Coulomb forces, i.e., electrical attraction and repulsion between the charge carriers, introduces a rich variety of many-body phenomena. It leads to the emergence of atom-like electron-hole quasi-particles, such as excitons, trions, and biexcitons, with unusually high binding energies and efficient light absorption.


    In this talk, I will focus on the physics of excitons in semiconducting 2D materials, largely determining the optical response of these ultra-thin layers. The observation of exciton binding energies on the order of many 100’s of meV and the marked deviation of the electron-hole attraction from the conventional Coulomb law will be discussed. The results reflect both strong carrier confinement and the distinctive nature of the dielectric screening in atomically thin systems. I will further describe how some of the more extreme non-equilibrium conditions such as strong photo-excitation and high electrical doping can profoundly alter the many-body interactions.

  • 17. Januar 2017

    Karl Jakobs (Uni Freiburg)

    From the Discovery of the Higgs Boson to the Search for Dark Matter

    -New results from the LHC-


    With the discovery of the Higgs boson by the two large experiments ATLAS and CMS at the Large Hadron Collider (LHC) at the European laboratory for particle physics CERN in Geneva, an important milestone in the investigation of the fundamental interactions was reached. Despite this discovery important questions remain open: does the discovered particle have the properties as predicted by the Brout-Englert-Higgs mechanism in the Standard Model or does it show devi­ations pointing to new physics? Are there new symmetries and -linked to them- new particles that could explain the Dark Matter in the Universe?


    In June 2015 a new data-taking period has started and proton-proton collisions are investi­gated with an energy of 13 TeV –nearly twice the collision energy used in the previous years. A new energy window opens up where the above-mentioned questions can be addressed. In the talk, the current status of the measurements at the LHC is presented. In particular, the properties of the discovered Higgs boson and the search for candidate Dark Matter particles are discussed.


  • 24. Januar 2017

    Angel Rubio (Max Planck Institute for the Structure and Dynamics of Matter, Hamburg)

    Modeling Light-Matter interaction: From Weak to Strong Coupling in QED Chemistry and Materials

    Computer simulations that predict the light-induced change in the physical and chemical properties of complex systems, molecules, nanostructures and solids usually ignore the quantum nature of light.  We have recently shown how the effects of the photons can be properly included in such calculations.  The basic idea is to treat the full QED system of particles and photons as a quantum fluid. Here the particles are represented by a charge current, and the photons by a classical electromagnetic field that acts on the current in a very complex manner.  This study opens up the possibility to predict and control the change of material properties due to the interaction with light particles from first principles .
    Here we will review the recent advances within density-functional a schemes to describe spectroscopic properties of complex systems with special emphasis to modeling  time and spatially resolved electron spectroscopies   We will discuss the theoretical approaches developed in the group  for  the characterization of matter out of equilibrium, the control material processes at the electronic level and tailor material properties, and  master energy and information on the nanoscale to propose new devices with capabilities. We will focus on examples  linked to the efficient conversion of light into electricity or chemical fuels ("artificial photosynthesis") and the design on new nanostructure based optoelectronic devices, among others.  
    Our  goal is to provide a detailed, efficient, and at the same time accurate microscopic approach for the ab-initio description and control of the dynamics of decoherence and dissipation in quantum many-body systems. This theoretical framework provides a new way to control and alter chemical reactions in complex systems,  direct the movement of electrons, selectively trigger physico-chemical processes, and create new state of matter.


  • 31. Januar 2017

    Axel Gross (Uni Ulm)
    Challenges in the theoretical description of electrochemical energy storage and conversion

    In spite of its technological relevance in the energy conversion and storage, our knowledge about the microscopic structure of electrochemical electrode-electrolyte interfaces and electrical double layers is still rather limited. The theoretical description of these interfaces from first principles is hampered by three facts. i) In electrochemistry, structures and properties of the electrodeelectrolyteinterfaces are governed by the electrode potential which adds considerable complexity to the theoretical treatment since charged surfaces have to be considered. ii) The theoretical
    treatment of processes at solid-liquid interfaces includes a proper description of the liquid which requires to determine free energies instead of just total energies. This means that computationally expensive statistical averages have to be performed. iii) Electronic structure methods based on
    density functional theory (DFT) combine numerical efficiency with a satisfactory accuracy. However, there are severe shortcomings of the DFT description of liquids, in particular water, using current functionals.

    Despite these obstacles, there has already significant progress been made in the first-principles modeling of electrochemical electrode-electrolyte interfaces. In this contribution, I will present our attempts to contribute to this progress by systematically increasing the complexity of the considered systems [1]. Different approaches to describe aqueous electrolytes at electrodes using first-principles calculations will be compared: the electrolyte can be described either as a thermodynamic reservoir or using implicit of explicit solvent models [2,3]. The equilibrium coverage of specifically adsorbed anions such as halides will be addressed which is an integral part of the realistic modeling of electrochemical double layers [2]. Furthermore, the modelling of electrocatalytic reactions occurring in fuel cells [3] will be presented. Finally, first attempts to model
    structures and processes in batteries using electronic structure calculations will be presented.

    [1] N. Hörmann, M. Jaeckle, F. Gossenberger, T. Roman, K. Forster-Tonigold, M. Naderian, S. Sakong, and A. Groß, Some challenges in the first-principles modeling of structures and processes in electrochemical energy storage and transfer, J. Power Sources 275, 531-538 (2015).

    [2] F. Gossenberger, T. Roman and A. Groß , Hydrogen and halide co-adsorption on Pt(111) in an electrochemical environment: a computational perspective, Electrochim. Acta 216, 152-159 (2016).

    [3] S. Sakong and Axel Groß, The importance of the electrochemical environment in the electrooxidation of methanol on Pt(111), ACS Catal. 6, 5575 (2016).
  • 07. Februar 2017

    Ronald Redmer (Universität Rostock)
    Warm Dense Matter - Probing Planetary Interiors

    The behaviour of warm dense matter (pressures up to the TPa region and temperatures up to several eV) is of paramount importance for understanding the interior, evolution and magnetic field of solar and extrasolar planets. While the light elements H and He are the main components of gas giants like Jupiter, mixtures of H-He-C-N-O are relevant for Neptune-like planets, and minerals of the MgO-FeO-SiO2 complex are the building blocks of rocky planets (Earth, super-Earths). The high-pressure phase diagram of these elements and mixtures has to be known in order to develop corresponding models. Of special interest in this context is the location of the melting line, of potential regions of phase separation and metal-insulator transitions. These high-pressure phenomena have a strong impact on interior, evolution, and dynamo models for planets and, simultaneously, constitute a major challenge to plasma and computational physics. 
    Molecular dynamics simulations based on finite-temperature density functional theory are used to predict the equation of state, the high-pressure phase diagram, and the transport properties of warm dense matter for a wide range of densities and temperatures as typical for the interior of planets. These data are benchmarked against diamond-anvil-cell and shock-wave experiments and then applied to construct interior and evolution models for solar and extrasolar planets.

  • 25. April 2017

    Hans Böhringer (Max-Planck-Institut für Extraterrestrischer Physik)

  • 16. Mai 2017

    Jürgen Blum (TU Braunschweig)
    Die Entstehung der Planetesimale im jungen Sonnensystem

  • 30. Mai 2017

    Claus Lämmerzahl (ZARM, Univ. Bremen)
    Quantenmechanik und Gravitation
  • 18. Juli 2017

    Reserviert (A. Piel)



Vorträge im SS 2017

Kolloquiumsvorträge (dienstags, 16.15 Hans-Geiger Hörsaal)


  • 18. April 2017

    Hans Böhringer (Max-Planck-Institut für Extraterrestrische Physik)

    Erforschung der Struktur unseres Universums mit Hilfe von Galaxienhaufen im Röntgenlicht

    Galaxienhaufen als größte klar definierte Objekte in unserem Universum sind ideale Testobjekte zur Vermessung der großräumigen, kosmischen
    Struktur und zum Test kosmologischer Modelle. Durch das mehrere 10 Millionen Grad heiße Plasma, das die Haufen ausfüllt, erscheinen die Haufen als besonders interessante Objekte in der Röntgenastronomie. Röntgenbeobachtungen bieten daher einen besonders guten Zugang zur Charakterisierung und zum Verständnis dieser Systeme.

    Aus dem Himmelsatlas im Röntgenbereich, der mit dem deutschen Röntgensatelliten ROSAT erstellt wurde, haben wir den größten Katalog röntgenleuchtender Galaxienhaufen ertellt und die Struktur von Stichproben dieser Haufen im Detail untersucht. Tests kosmologischer Modelle mit Hilfe dieser Daten liefern z.B. einen Wert für die mittlere Materiedichte unseres Universums.
    Das Ergebnis zeigt, dass wir zur Erklärung der Beobachtungen eine bisher unbekannte "Dunkle Materie" brauchen, und dass möglicherweise ein
    kleinerer Teil dieser Materie aus Neutrinos mit endlicher Restmasse besteht. Beim Studium der Materieverteilung im nahen Universum stellen wir fest, dass wir uns in einer Umgebungen mit weniger als mittlerer Materiedichte befinden, mit wichtiger Auswirkung auf die lokale Hubble Konstante im Vergleich zu ihrem globalen Wert.

  • 2. Mai 2017

    Thomas Frauenheim (Uni Bremen)
    Multi-scale modeling of nanostructured devices

    Presently electronic and optoelectronic devices scale down to nanometer sizes at which quantum atomistic modeling can be used to understand the fundamental mechanisms and optimize quality and performance. In this talk I am going to describe recent developments of DFTB-based atomistic and charge transport simulations addressing applications to ultra-scaled Silicon-on-Oxide electronic devices and nanostructured solar cells and light emitting diodes.

    (1) Ultimate scaling of Si MOSFETs leads to extremely thin and short channels, which are justifiably modeled at the atomic level. Currently, hydrogen-termination of the channel is used in device models, as a compromise between efficiency and accuracy. This work advances the state of the art by adopting a density-functional tight-binding (DFTB) Hamiltonian, permitting the inclusion of the confining oxide explicitly in the simulation domain in an ab initio fashion. Simulations of band-structure and electron transport in extremely thin SOI MOSFET are studied with this method, showing good agreement with experiment and reveal a large quantitative difference when compared to simulations with H-passivated channel. S. Markov et al. IEEE Transaction on Electron Devices 62 (2015) 696.

    (2) simulations of photovoltaic devices are based on classical models, which neglect the atomistic details and quantum-mechanical effects besides the dependence on many empirical parameters. Within the nonequilibrium Green’ s function formalism, we present a quantum-mechanical study of the performance of inorganic nanowire-based photovoltaic devices. On the basis of density-functional tight-binding theory, the method allows simulation of current− voltage characteristics and optical properties of photovoltaic devices without relying on empirical parameters. Numerical studies of silicon nanowire-based devices of realistic sizes with 10 000 atoms are performed, and the results indicate that atomistic details and nonequilibrium conditions have a clear impact on the photoresponse of the devices. Y. Zhang, et al. Journal of Ohys. Chem. Letters, 5 (2014) 1272.

    (3) Understanding of the electroluminescence (EL) mechanism in optoelectronic devices is imperative for further optimization of their efficiency and effectiveness. Here, a quantum mechanical approach is formulated for modeling the EL processes in nanoscale light emitting diodes (LED). Based on non-equilibrium Green’s function quantum transport equations, interactions with the electromagnetic vacuum environment are included to describe electrically driven light emission in the devices. The presented framework is illustrated by numerical simulations of a silicon nanowire LED device. EL spectra of the nanowire device under different bias voltages are obtained and, more importantly, the radiation pattern and polarization of optical emission can be determined using the current approach. This work is an important step forward towards atomistic quantum mechanical modeling of the electrically induced optical response in nanoscale systems. R. Wang, et al. Nanoscale ( (2016) 13168.

    If time allows, I will report on the time-dependant DFTB implementations and describe recent applications to nitric oxide degradation on titania surfaces and hot electron injection into TiO2 nanoparticles.

  • 16. Mai 2017

    Jürgen Blum (IGeP, TU Braunschweig)
    Die Entstehung der Planetesimale im jungen Sonnensystem

    Unser Wissen über die Entstehung der Planeten ist immer noch lückenhaft. Aus astronomischen Beaboachtungen können wir lernen, dass Planeten in so genannten protoplanetaren Scheiben entstehen, die zu 99% aus Gas und zu 1% aus mikroskopisch kleinen Staubpartikeln bestehen. In diesen Scheiben kollidieren die Staubteilchen, haften aneinander und bilden bis zu zentimetergroße Agglomerate. Dies konnte durch Modellierung, 
    Labormessungen und astronomische Untersuchungen bestätigt werden. Das weitere Wachstum hin zu Planetesimalen, den kleinsten gravitativ 
    gebundenen Körpern mit Durchmessern von einigen Kilometern, wird zurzeit noch kontrovers diskutiert. Die beiden favorisierten Modelle 
    unterscheiden sich darin, dass im einen das Wachstum aufgrund haftender Stöße fortschreitet, im anderen hingegen eine hydrodynamische 
    Instabilität in der protoplanetaren Scheibe, die "Streaming Instability", für eine so starke Konzentration der zentimetergroßen Staubklumpen sorgt, dass der gesamte Komplex gravitativ kollabiert.
    Mit der jüngst abgeschlossenen Mission Rosetta zum Kometen 67P/Tschurjumow-Gerassimenko konnte erstmals ein Körper aus den Frühzeiten des Sonnensystems im Detail untersucht werden. Die bislang vorliegenden Ergebnisse deuten darauf hin, dass Komet 67P durch einen gravitativen Kollaps in seiner heutigen Form entstanden ist. Wenn sich dies bestätigen sollte, liegt der Schluss nahe, dass Planetesimale nicht durch haftende Stöße, sondern durch Instabilitäten in protoplanetaren Scheiben entstehen.

  • 13. Juni 2017,
    Beginn 17.15Uhr (!)

    Tiberiu Minea (U Paris-Sud, Frankreich)
    Modeling of vacuum breakdown. Thermo-field, dynamics of microparticles and laser assisted electron emission

    Vacuum is often used as an isolator in numerous applications, such as X-ray tubes, particle accelerators, high voltage pass-through, etc. However, their performance is limited by the risk of unpredictable breakdown events between electrodes. Moreover, the breakdown usually leads to the formation of arc discharges, which can seriously damage the system.

    Since 2010 the LPGP develops a research program “High Voltage holding In Vacuum”, in collaboration with CEA and CentraleSupelec which aims to give a better description of the origin of the vacuum breakdown.

    Three numerical models have been developed to tackles three particular aspects of the problem.

    (i) The model OVIP (Orsay Vacuum Insulation Percolation) deals with the thermos-field electron emission from a surface microprotrusion and the results are in good agreement with the experimental results for breakdown. The operation with fast pulses allows to enhance the field emission avoiding the breakdown.

    (ii) The model OFEN (Orsay Field Emission Nanoparticles) describes the micro-particles (MP) transport in the inter-electrodes gap, in vacuum) and the interactions (heating and modification of the MP charge) between electrons and the MP. It is an extension of the Cranberg’s theory of clumps when the MP is exposed to an intense field ~1-5 MV/m and it is simultaneous bombarded by electrons released from the cathode micro-tips. The results clearly show four different regimes of MP trajectories obtained for different emission currents, MP sizes and inter-electrode distances and the effect of the MP crash of on the cathode, helping to understand the vacuum conditioning.

    (iii) The last model OFELIE (Orsay Field Emission and Light Emission) analysis the electron emission induced by picosecond laser from solid surfaces placed under an intense electric field. The results show an important difference between the electrons temperature (5500 K) and the phonons temperature (850 K). In these conditions, the Fermi-Dirac distribution depends of the electron temperature, while the thermo-field emission becomes effective for temperatures well below the fusion of the metal.

    In conclusion, the modeling of the related phenomena between solid and vacuum depends on the way the energy is transferred to the electrons and it helps to distinguish between different scenarios and to design performant systems.
  • 04. Juli 2017

    Eberhard Möbius (Space Science Center and Department of Physics, University of New Hampshire)

    Astronomy with Neutral Atoms - Imaging the Heliospheric Boundary and Catching the Interstellar Wind with the Interstellar Boundary Explorer

    400 years after Galileo pointed a telescope at celestial objects for the first time, neutral atoms were added to the astronomical toolbox with the Interstellar Boundary Explorer (IBEX), launched October 19, 2008. Since early 2009, two energetic neutral atom (ENA) cameras take global images of the solar system’s interaction with its galactic neighborhood. They have returned stunning images of the heliospheric boundary region, where the solar wind slows down in response to the surrounding interstellar medium, including the front and tail region of the heliosphere. Most unexpectedly, the images show a bright and persistent “Ribbon” across the sky, which provides a marker for the direction of the local interstellar magnetic field, but the processes leading to the bright ENA emission are still being investigated. Time variations in the ENA fluxes that vary with energy provide additional constraints and point to the neutral solar wind that penetrates beyond the boundary of the heliosphere. The IBEX-Lo camera catches the interstellar wind of neutral H, He, O, and Ne atoms that blows through the solar system with a speed of ≈26 km/s and arises from the motion of the Sun relative to the surrounding local interstellar gas cloud (LIC). This observed gas flow distribution is an excellent probe of the state of the LIC and shows clear signatures of the deflection of the interstellar plasma at the heliospheric boundary.

  • 11. Juli 2017

    Erwin O. Flückiger
    60 Jahre Neutronenmonitor

  • 18. Juli 2017, 15:00 Uhr

    Abschiedskolloquium von Prof. Piel


Vorträge im WS 2017/2018

  • 24.10.2017

    Dr. Gerard van Rooij (Dutch Institute for Fundamental Energy Research DIFFER, Eindhoven) abstract
    Electrification of chemical industry: a key role for plasma chemistry

    Sustainable energy generation by means of wind or from solar radiation through photovoltaics or concentrated solar power will continue to increase its share of the energy mix. Intermittency due to e.g. day/night cycle, regional variation in availability, and penetration of sustainable energy into sectors other than electricity such as the chemical industry necessitates means of storage, transport and energy conversion on a large scale. A promising option is the synthesis of chemicals and artificial fuels using sustainable energy. A truly circular economy requires that the raw materials are the thermodynamically most stable ones such as CO_2 and N_2 . In this contribution it will be highlighted how plasma chemistry can potentially combine compatibility with e.g. intermittency and localized production to activate these molecules with maximum energy efficiency, essentially due to preferential vibrational excitation (causing inherently strong out-of-equilibrium processing conditions that achieve selectivity in the reaction processes). Examples will be discussed of research carried out at DIFFER to ultimately enable a scale up to chemical industrial applications.


  • 07.11.2017

    Dr. Volker Schulz-von der Gathen (Fakultät für Pysik und Astronomie der Ruhr-Universität Bochum)
    Microplasma arrays: Concept, configuration, characteristics and potential applications


Der Vortrag von Dr. Schulz-von der Gathen am 07. November fällt auf Grund von Krankheit leider aus! Der Neue Termin wurde für die 09.01.2018 festgelegt.
  • 21.11.2017

    Dr. Michael Klick (Plasmatrex, Berlin) abstract
    Zur Plasma-Wand-Wechselwirkung in industriellen HF-Plasmen​

    Die Plasma-Wand-Wechselwirkung ist für die industrielle Nutzung von chemisch aktiven HF-Plasmen von fundamentaler Bedeutung. Im Bereich des Plasma-Ätzens in der Halbleiter-Industrie ist die sogenannte Konditionierung von Prozesskammern nach einer Reinigung im Abstand von einigen Wochen oder Monaten Vorbedingung für die Freigabe zur Fertigung. Dies trifft aber auch für PECVD-Kammern im laufen-den Betrieb zu, da die auch auf der Wand abgeschiedene Schicht i.a. wieder zurück geätzt werden muss. [mehr im abstract]

  • 28.11.2017

    Prof. Dr. Claus Lämmerzahl (ZARM, Bremen) abstract
    An operational foundation of General Relativity and the search for Quantum Gravity

    General Relativity seems to be incompatible with the principles of quan-tum theory. Therefore, a new theory - Quantum Gravity - is expected to replace General Relativity which also should lead to new physical effects. However, no finally worked out Quantum Gravity theory exists. In order to be able to already design experiments searching for expected effects of Quantum Gravity one has to carry out such experiments which give a foundation of General Relativity. Such a program is described in this talk: Based on an constructive axiomatic approach to General Relativity from Ehlers, Pirani, and Schild experiments are described which have the poten-tial to find deviations from standard physics related to Quantum Gravity.

  • 12.12.2017

    Prof. Dr. Peter Schmelcher (Universität Hamburg) abstract
    Mesoscopic Physics with Ultracold Atoms: From Few- to Many-Body Systems

    Bose-Einstein condensates, matter waves and generally ultracold atomic physics have seen over the past two decades a breathtaking development and represent nowadays an important part of modern quantum physics. We provide here an overview of me-soscopic aspects of ultracold atomic structures and processes in tightly confining traps. For strongly interacting ultracold atoms novel tunneling mechanisms occur which play a key role for the atomic transport and the formation of rich quantum pha-ses. We demonstrate a variety of tunneling processes which are the basis of the emerging field of atomtronics, some of them being counterintuitive, such as the tun-neling of repulsively bound atomic clusters.
    A special focus will be on the none-quilibrium quantum dynamics of ultracold bosonic and fermionic ensembles where correlations determine the response due to a quantum quench or a continuous driving. Recent methodological developments allow to explore the correlated dynamics in the crossover regime from few- to many-body systems in order to understand the emergence of collective behaviour.

  • 19.12.2017

    Dr. Kählert (Reserviert)

  • 09.01.2018

    Dr. Volker Schulz-von der Gathen (Fakultät für Pysik und Astronomie der Ruhr-Universität Bochum) abstract
    Microplasma arrays: Concept, configuration, characteristics and potential applications

    Microplasma arrays belong to the class of low temperature non-equilibrium atmospheric pressure plasma devices. They consist of huge numbers of about 100 micrometer size cavities regularly positioned on a common ground. These structures are usually generally manufactured applying microstructure techniques on silica wafers [1], but other configurations have been investigated recently. Being basically dielectric barrier discharges, the devices are typically driven by a single power supply at kHz frequencies at voltages of a few hundred volts. Due to the small dimensions strong fields exist in close contact with the surfaces that introduces new physical features. The geometric configuration results e.g. in unique features of discharge dynamics as ionization waves. A huge number of possible applications have been proposed over the last years [2]. The examples range from photonic applications as light generation and detection to large scale surface treatments or use as meta materials. In this talk we will give a basic description of the concepts of microplasma arrays, their operation and some application possibilities. Subsequently we will describe some of the physical features observed mainly by analysis of optical emission.

    [1] J.G. Eden, S.-J. Park, and K.-S. Kim, „Arrays of non-equilibrium plasmas confined to microcavities: an emerging frontier in plasma science and its applications“ Plasma Sources Science and Technology, 2006, 15, S67-S73
    [2] J.G. Eden, and S.-J. Park, „Microcavity plasma devices and arrays: a new realm of plasma physics and photonic applications“, Plasma Phys Control Fusion, 2005, 47, B83-B92

  • 16.01.2018

    Prof. Dr. Ulrich Stroth (TU München/IPP) abstract
    Über die zentrale Bedeutung des Plasmarandes für die Fusionsforschung

    Der Votrag beschreibt die physikalischen Prozesse, die den Rand des Fusionsplasmas auszeichnen, wo der Übergang vin einem bis zu 100 Millionen Grad heißen Plasma zu den umgebenden matiellen Wänden vollzogen wird. Die Forschung auf diesem Gebiet ist stark interdisziplinär. Sie greift auf Konzepte aus verschiedenen Fachgebieten zurück, angefangen bei der Festkörperphysik, über die Atmo- und Molekülphysik und die Magnetohydrodynamik, bis hin zur Plasmaturbulenz. Durch die Darstellung ausgewählter Prozesse wird das Zusammenwirken der verschiedenen Einflüsse auf das Plasma sichtbar gemacht.
    Das Verständnis des Plasmaranders ist insbesondere dazu notwendig, um eine sichere Leistungabfuhr aus Fusionsplasmen zu gewährleisten. Mögliche Realisierungendes Plasmarandes für ein Fusionskraftwerk werden beispielhaft and den Experimenten des MPI für Plasmaphysik, dem Tokamak ASDEX Upgrade und dem Stellarator Wendelstein 7-X, dargestellt.

  • 23.01.2018

    Prof. Dr. Stefan Kuhr (University of Strathclyde, Glasgow) abstract
    Quantum-Gas Microscopes - Quantum-Simulation with Single-Particle Access

    Ultracold atoms in well-controlled engineered environments in optical lattices are a versa-tile tool for quantum-simulation of strongly correlated quantum systems. The most recent developments in this field include quantum-gas microscopes [1], enabling single-lattice-site resolution and single-atom control [2]. Imaging of with single-atoms resolution has made it possible to directly observe bosonic and fermionic many-body quantum systems in an un-precedented way, giving access to, e.g., in-situ measurements of temperature and entropy distributions, direct observation of correlations and their spreading, or the build-up of en-tanglement. I will present how we achieved single-atom-resolved fluorescence imaging of fermionic potassium-40 atoms using electromagnetically-induced-transparency (EIT) coo-ling [3], and a new way of Raman gray-molasses cooling [4]. I will also report on our pro-gress towards the creation of fermionic Mott insulators and the study of strongly correlated fermionic quantum systems and their out-of-equilibrium dynamics.

  • 30.01.2018

    Prof. Dr. K. Hassouni (Université Paris, France) abstract
    Nanoparticles formation in non-equilibrium plasmas

    Dusty plasmas were observed and investigated since the early 20th century in the context of astrophysical sciences, the early eighties in the context of material processing plasmas and for more than two decades in the context of edge tokamak plasmas and their interaction with fusion reactor materials.
    Surprisingly, the physical mechanisms and collisional processes that lead to the formation of dust particles in plasmas received little attention during the last century. The situation changed with the strong increase of interest for nanomaterial processing and the advent of ITER project. As a matter of fact, dusty plasmas were considered as a promising tool for making and processing functional nanomaterials with unique properties for a variety of applications. On the other hand, the formation of dust particles in tokamak edge plasmas represents a major safety concern and motivated a large research effort with the aim to understand the phys-ical mechanism that lead to the formation of these particles and to propose a way to inhibit these mecha-nisms. (Read more in the attached abstract)

  • 06.02.2018

    Prof. Dr. Livio Narici, INFN (Italian National Institute for Nuclear Physics), Rome abstract
    Anomalous light flashes & other sensory illusions due to charged particles in space and hadrontherapy

    In 1952 an article appeared in Journal of Aviation Medicinehypothesizing the poten-tial hazard of the cosmic rays in spaceflight. Dr. Tobias predicted that individual heavy ions passing through the retina might produce visual effects. In 1969, Edwin Aldrin reported mysterious visual stars and streaks during his lunar mission. This started a still ongoing interest on if and how cosmic radiation could modulate sen-sory and, more at large, brain activity, and if this could represent a functional health hazard. Many researches on ground (especially in the beginning of the 70’s) have been carried on, followed by a smaller number of space experiment (on the Apollo, Skylab, Apollo-Soyuz). More recently the interest revitalized with several investiga-tions both on ground (also on patients undergoing hadrontherapy) and in space. Since Tobias’ prediction we now know that not only heavy ions are producing sen-sory illusions, but also light ions, even protons. And there are also indications that all sensory channels and, possibly, also other brain activities, can be modulated by charged radiation. In this talk a brief history of the light flashes studies followed by a panorama of what is becoming evident about other sensory systems involvement will be presented. Experimental results from the ALTEA program about in vitro and in vivo (on animal models) investigations as well as about studies on humans (pati-ents and astronauts) will be presented.

Vorträge im SS 2018

  • 24.04.2018

    Prof. Dr. Jan Benedikt (CAU IEAP), Kiel abstract
    Kalte Nicht-Gleichgewichts-Plasmen für neuartige Forschung und Anwendungen

    Nicht-Gleichgewichts-Plasmen besitzen vielfältige Anwendungsmöglichkeiten, die vom Satellitenantrieb über die Herstellung von nanostrukturierten Elektronikbautei-len und der Abscheidung von ultraharten Schutzschichten bis hin zur Plasma-Sterilisation oder Plasmatherapie in Medizin reichen. In diesen Plasmen haben nur die Elektronen sehr hohe Temperaturen (mehrere 10.000 Grad), die Schwerteil-chen (Atome, Moleküle, Ionen) bleiben dagegen kalt. Sie sind normalerweise in ei-nem Gas im Niederdruckbereich realisiert, in welchem hauptsächlich die Elektronen durch die elektrischen Felder beschleunigt werden und die Nicht-Gleichgewichtssituation durch eine geringere Stoßfrequenz und Energieübertrag gewährleistet ist. Nicht-Gleichgewichts-Plasmen kann man aber auch bei Atmo-sphärendruck durch gepulste Felder, Begrenzung des Stromes oder Hochfrequenz-felder realisieren. Die energetischen Elektronen führen zur Anregung von Atomen und Dissoziation von Molekülen, was eine Reaktivität des Gases erreicht, die sonst nur bei viel höheren Gastemperaturen stattfinden würde. Darüber hinaus werden Ionen in Richtung Oberfläche beschleunigt und können sehr feine, aber auch sehr tiefe Strukturen ätzen. In diesem Vortrag werden zuerst die Diagnostik der reakti-ven Plasmakomponenten wie Radikale, Ionen oder Vakuum-UV Strahlung disku-tiert und danach die Plasmaanwendungen in multidisziplinären Feldern der Materi-alsynthese oder Plasmamedizin vorgestellt.

  • 08.05.2018

    Prof. Dr. A. Anders (Leibniz Institute of Surface Engineering (IOM), Leipzig) abstract
    Plasma Potential Distribution and Electron Heating in Sputtering Magnetrons

    Sputtering magnetrons are widely used to make thin films and are generally consid-ered a mature technology. Over the last years it has become known that magnetrons show surprisingly rich physics based on plasma instabilities. Without these instabili-ties, magnetrons would generally not work. The energy needed to ionize atoms of the process gas and sputtered from the target is generallythought to be delivered by "hot" secondary electrons (Penning-Thornton paradigm). Recent theoretical [1], spectro-scopic [2], and probe data [3] however indicate that most of the electrons’ energy comes from the presheath, and is provided by localized electric fields concentrated at the edge of "ionization zones" or "spokes" [4, 5]. This is closely related to self-organization and turbulence as observed in interesting images of magnetron plasmas.

  • 15.05.2018

    free - but no accommodation - Special Olympics Deutschland in Kiel

  • 29.05.2018

    Prof. Dr. Ulf Helmersson (Linköping University, Schweden), abstract
    Wires, trusses and pillars produced by assembly of plasma generated nanopartices

    Nanoparticles generated or supplied to a plasma attains a negative potential due to the nature of the plasma. This open up interesting possibilities in synthesis and assembly of the nanoparticles creating structures in the nano- and micro-range. In this work, we use hollow cathode sputtering powered with high-power pulse to ensure close to full ionized of the source material. This promotes rapid growth of the nanoparticles to desired sizes and the negative charge makes it possibility to guide nanoparticles for assembly and collection on desired positions. This is demonstrated by attracting na-noparticles to substrate positions with a positive potential and focusing nanoparticles through a matrix of electrostatic lenses to assemble the nanoparticles into pillars. For ferromagnetic nanoparticles, we also demonstrate generation of nanowires as well as nanowires cross-linked into trusses. Since the iron nanoparticles are generated under relatively pure condition they assemble into wires without oxides in the interfaces. Nanowires and trusses assembled on conducting substrates can potentially be used as low cost large area electrodes.

  • 05.06.2018


  • 12.06.2018

    Prof. Dr. Francis Halzen (Wisconsin IceCube Particle Astrophysics Center and Department of Physics) University of Wisconsin–Madison, abstract
    ICE CUBE and the Discovery of High-Energy Cosmic Neutrinos

    The IceCube project has transformed a cubic kilometer of natural Antarctic ice into a neutrino detector. The instrument detects more than 100,000 neutrinos per year in the GeV to PeV energy range. Among those, we have isolated a flux of high-energy cosmic neutri-nos. I will discuss the instrument, the analysis of the data, the signi-ficance of the discovery of cosmic neutrinos, and the recent multi-messenger observation of a flaring TeV blazar in coincidence with the IceCube neutrino alert IC170922. The large cosmic neutrino flux observed implies that the Universe’s energy density in high-energy neutrinos is the same as that in gamma rays, suggesting that the sources are connected and that a multitude of astronomical objects await discovery.

  • 19.06.2018

    Prof. Dr. Cornelia Denz (Institut für Angewandte Physik) Westfälische Wilhelms-Universität Münster abstract
    Complex light fields for optical manipulation of nanoparticles and cells

    Light can hold, move and measure micro- and nano particle without touching. This allows implementing a device named optical tweezers which exploits focused laser light to trap and manipulate small particles. When using complex tailored light fields based on holographic principles, optical tweezers become an extraordinary metrology tool for analysis in nanophotonics or biophysics.

  • 26.06.2018

    Prof. Dr. Thomas Mannel (Universität Siegen, Germany), abstract
    Particle Physics after the Higgs Discovery: Where do we go?

    After the recent discovery of the Higgs boson the so-called Standard Model of particle physics has become a complete and mathematically consistent theory, which – at least in principle – could be valid up to extremely high energies. In this talk I will discuss, why research in particle physics is still well motivated, although the Higgs boson is discovered. I will consider on the one hand the theoretical problems of the standard model, on the other hand, I will discuss experimental hints, why the standard model cannot be the final theory of the fundamental interactions.

  • 03.07.2018

  • 10.07.2018

  • 17.07.2018

Vorträge im WS 2018/2019

  • 30.10.2018

    Dr. Katrin Amann-Winkel (Stockholm University),  abstract - [Magnussen]
    “Does water consist of two liquids? How X-rays reveal water ́s mysteries”

    Water is ubiquitous and the most important liquid for life on earth. Although the water molecule is seemingly simple, various macroscopic properties of water are most anomalous, such as the density maximum at 4°C or the divergence of the heat capacity upon cooling. The fundamental origin of these anomalies is yet to be fully understood [1]. Computersimulations suggest that the anomalous behaviour of ambient and supercooled water could be explained by a two state model of water. An important role in this ongoing debate plays the amorphous forms of water [2]. Since the discovery of two distinct amorphous states of ice with different density (high- and low density amorphous ice, HDA and LDA) it has been discussed whether and how this phenomenon of polyamorphism at high pressures is connected to the occurrence of two distinct liquid phases (HDL and LDL) [3]. X-ray scattering experiments on both supercooled water [4] and amorphous ice [5] are of major importance for our understanding of water. In my talk I will give an overview on our recent experiments on micrometer-sized supercooled water droplets [4] and amorphous ices [5]. Among other techniques, X-ray correlation spectroscopy (XPCS) was used to study the dynamics in amorphous ice around the hypothesized glass transition tempera- ture. Our results are consistent with the hypothesis of a liquid-liquid transition between HDL and LDL [3,4,5].

    [1] Nilsson, A. & Pettersson, L.G.M., The structural origin of anomalous properties of liquid water. 6, 8998, Nature Comms (2015)
    [2] K. Amann-Winkel et al., Water ́s controversial glass transition, Rev. Mod. Phys. 88, 0110002 (2016)
    [3] P. Gallo, K. Amann-Winkel et al., Water: a Tale of Two Liquids, Chem. Rev. 116, 7463-7500 (2016)
    [4] K.H. Kim, A. Spaeh et al., Maxima in the Thermodynamic Response and Correlation Functions of Deeply Supercooled Water, SCIENCE 358, 1589 (2017)
    [5] F. Perakis, K. Amann-Winkel et al., Diffusive dynamics during the high-to-low density transition in amor- phous ice, PNAS 114, 8193 (2017)

  • 06.11.2018
  • 13.11.2018

    Dr. Andreas Dorsel (Zeiss SMT, Oberkochen),  abstract - [Duschl]
    “ZEISS Semiconductor Manufacturing Technology“
    ...where Science meets Industry...

    The advent of Micorelectronics, ubiquitous in all areas of life today, has often been referred to as the third industrial revolution. Semiconductor manufacturing technologies are key in enabling this dramatic development. This talk will try to point to answers questions like
    • Which technologies are key?
    • What are the drivers for these technologies?
    • What are limitations resulting from the laws of physics?
    • What has been achieved and what is considered achievable?
    • What is different when comparing science and academia vs. development and in- dustry
  • 20.11.2018
  • 27.11.2018

    Prof. Dr. Andreas Eckart (Universität zu Köln),  abstract - [Duschl]
    The central light-year of the Milky Way
    How stars and gas live in a relativistic
    environment of a super-massive black hole

    The central region of our Milky Way is an extremely active region. It is the closest galactic nucleus that is accessable to us allowing us to study it in fine detail. Here we present most recent results obtained with state of the art instruments providing sensitive measurments at their highest angular resolution. The central star cluster harbors a small cusp of high velocity mostly young and dusty stars that are in orbit around the 4 million solar mass super massive black hole (SMBH) Sagittarius A* (SgrA*). Molecular and atomic gas is streaming towards this region in the form of a spiral connecting it to the Circum Nuclear Ring. Using the Large Atacama Millimeter Array (ALMA) we investigated the kinematics and composition of this material in detail highlighting signatures of star formation and the interaction with a wind emerging form the direction of SgrA*. Using results from the Very Large Telescope (VLT) we will highlight the dynamics of the ultra-fast stars and present theories on their origin. We demonstrate that one of the innermost stars shows clear signs of relativistic motion in the deep potential well of the SMBH. The interaction of plasma with SgrA* reveals that matter is orbiting and is being accreted onto the SMBH to produce powerful flares. These are detectable all across the electromagnetic spectrum and help us to understand the region close to the event horizon of SgrA* which is currently under investigation using the Event Horizon Telescope (EHT).
  • 04.12.2018

    Dr. Michael Zeuner (scia systems, Chemnitz), abstract - [Kersten]
    "Ionenstrahl- und Magnetronsputterverfahren für moderne Oberflächenanwendungen“

    Anwendungen bei der Fertigung von MEMS (Mechanisch-elektrische Mikrosysteme) erschließen zahlreiche neue Anwendungen für Plasma- und Ionenstrahlverfahren, insbesondere gilt das für die Fertigung von Baugruppen und Schaltkreisen für die Mobilkommunikation. Im Vortrag wird speziell auf Fertigungsverfahren für passive Hochfrequenzfilter eingegangen. Mit der modernen Mobilkommunikation hat sich die Hochfrequenzelektronik stürmisch entwickelt. Unterschiedlichste Informationen werden auf verschiedenen Frequenzbändern übertragen, so dass heutige Mobiltelefone bis zu 50 Frequenzfilter enthalten. Die Filter nutzen akustische Resonatoren, um eine notwendige Miniaturisierung vornehmen zu können. Je nach Frequenzbereich werden die Filter als Oberflächenwellenfilter SAW) oder Volumenresonatoren (BAW) ausgelegt. Der Vortrag stellt daher einleitend Anforderungen und Funktionsprinzipien dieser Filterbauelemente dar.
    In den Filtern werden piezoelektrische Materialien bzw. Schichtsysteme eingesetzt, die in geometrischen Dimensionen exakt auf die Zielfrequenzbänder eingestellt werden müssen. Über Magnetronsputtern werden einerseits piezoelektrischen Schichten mit hohen piezoelektischen Koeffizienten hergestellt, andererseits auch sogenannte Temperaturkompensationsschichten, die thermische Drift der Bauelemente zumindest einschränken soll. Trotz ausgefeilter Abscheideverfahren werden bei weitem nicht die Eigenschaftstoleranzen erreicht, um eine ideale Ausbeute an Filtern auf Waferlevel zu erzielen, daher müssen die Filter zwangsläufig auf die exakte Zielfrequenz getrimmt werden. Ein solcher Trimmprozess erfolgt durch verweilzeitgesteuerte Ionenstrahlen mittels deren Toleranzen bis in den sub-nm-Bereich korrigiert werden können. Der Vortrag präsentiert Verfahren, Ausrüstung und Ergebnisse zur Abscheidung der piezoelektrischen Schichten als auch zum finalen Frequenztrimmen der Filterbauelemente.
  • 11.12.2018
  • 18.12.2018
  • 08.01.2019

    Dr. Bridget Murphy , abstract - [Magnussen]
    (Institute of Experimental and Applied Physics, Kiel University
    Ruprecht Haensel Laboratory, Kiel University)

    "Archaeometry: The Role of Physics in the Quest to Understand Qumran“

    The famous Dead Sea scrolls, found in 1947 at Qumran, point to a group of people, the ‘Essenes’, described by famous philosophers including Pliny and Flavius Josephus. In 1998, interdisciplinary laboratory research started in Jerusalem between materials scientists, museum curators and archaeologists to obtain fresh information of what the manuscripts and the material culture may demonstrate, and how to preserve this cultural heritage for the centuries to come. While the primary question of ‘who wrote the scrolls and where’ remains unanswered this project opened a golden opportunity to employ archaeometry analytical techniques including structural analysis and spectroscopy to investigate the scroll parchment[1] and textiles[2] from Qumran[3]. In this lecture, I will explain how physics can provide non-destructive methods for investigating ancient artefacts. I will introduce the methods and explain how modern infra-red and florescence spectroscopic and neutron and X-ray methods can provide insight into the ancient practices and processes and also give us hints on how best to preserve these valuable antiquities.

    [1] B. Murphy, M. Cotte, M. Mueller, M. Balla, J. Gunneweg, in Holistic Qumran. (Brill, 2010), vol. 87, pp. 77-98.
    [2] M. Muller, B. Murphy, M. Burghammer, C. Riekel, E. Pantos, J. Gunneweg, Ageing of native cellulose fibres under archaeological conditions: textiles from the Dead Sea region studied using synchrotron X-ray microdiffraction. Applied Physics A: Materials Science & Processing 89, 877-881 (2007).
    [3] H. J.B., G. J., Khirbet Qumran et Ain Feshkha II, Novum Testamentum et Orbis Antiquus, Series Archaeologica 3. ( Academic Press Fribourg; Vandenhoeck & Ruprecht., Fribourg; Göttingen;, 2003).
  • 15.01.2019

    Prof. Dr. Karsten Danzmann (MPI für Gravitationsphysik und Universität Hannover), abstract - [Dau,Duschl]
    "Gravitational Wave Astronomy: Listening to the sounds of the dark universe!"

    For thousands of years we have been looking at the universe with our eyes. But most of the universe is dark and will never be observable with electromagnetic waves. Since September 14th, 2015, everything is different: Gravitational waves were discovered! We have obtained a new sense and finally we can listen to the dark side of the universe. The first sounds that we heard were from unexpectedly heavy Black Holes, which we are now routinely and frequently detecting. The observation of a neutron star merger opened the era of multi-messenger astronomy. Low-Frequency gravitational wave signals from supermassive black holes will soon be detected by the space detector LISA. And the laser technology developed for gravitational wave detection is now being used for earth observation with the GRACE Follow-on mission.

  • 22.01.2019
  • 29.01.2019

    Prof. D. C. Johnson (Materials Science Institute and Department of Chemistry, University of Oregon), abstract - [Rossnagel]
    "Materials by Design: Heterostructures with Targeted Nanoarchitecture and Tunable Properties"

    We have shown that by controlling the local composition of an amorphous intermediate on the nanoscale it is possible to kinetically control the self-assembly of new nanostructured compounds consisting of two or more compounds with different crystal structures that are precisely interleaved
    on the nanoscale. We have used this approach to synthesize hundreds of new metastable compounds with designed nanostructure, including structural isomers. Many of these materials have unprecedented physical properties, including the lowest thermal conductivities ever reported for a
    fully dense solid, systematic structural changes dependent on nanostructure, and charge density wave transitions. The designed precursors enable diffusion to be followed and quantified over distances of less than a nanometer, providing insights to the mechanism that gives control of the
    nanoarchitecture of the final product. We believe the ability to prepare entire families of new nanostructured compounds and equilibrating them to control carrier concentrations permits a new "thin film metallurgy" or “nanochemistry” in which nanostructure and composition can both be
    used to tailor physical properties, interfacial structures can be determined for precisely defined constituent thicknesses, and interfacial phenomena and modulation doping can be systematically exploited.

  • 05.02.2019

    PD Dr. Horst Fichtner (Ruhr-Universität Bochum, Institut für Theoretische Physik IV), abstract - [Heber]
    "Power Laws in Heliospheric Physics: Evidence for Nonlinear Diffusion, Anomalous Transport and Non-Extensive Entropy?"

    Numerous measurements of space plasmas and energetic particles by many spacecraft, including the two Voyagers that have by now both left the heliosphere, have revealed the almost ubiquitous presence of power-law behaviour of distribution functions both in velocity and in configuration space. Besides being indicative of acceleration and transport processes, such power laws have been considered as evidence for `non-standard' physics, particularly for so-called anomalous transport and for a non-extensive, i.e. non-additive entropy. The talk will demonstrate how heliospheric physics can contribute to answer related questions and, thus, how it is related to such fundamental aspects of physics.

  • 12.02.2019

    Dr. Jingnan Guo (Institute of Experimental and Applied Physics, Kiel University), abstract - [Wimmer-Schweingruber]
    "Understanding the Heliospheric Radiation Environment in Preparation for Human Explorations to Mars"

    Potential radiation damage to astronauts induced by Solar Energetic Particles (SEPs) and Galactic Cosmic Rays (GCRs) in space is one of the most important risks for future human space missions, especially interplanetary missions such as to Mars which requires a long mission duration of at least 2-3 years. To evaluate such radiation risks for deep space missions, in particular in preparation for future human explorations to Mars, the Radiation Assessment Detector (RAD) was designed to detect and analyze the most biologically hazardous energetic particle radiation during the cruise to Mars and on the Martian surface as part of the Mars Science Laboratory (MSL) mission.

    MSL was launched on November 26, 2011 and landed on Mars on August 6, 2012 after a 253-day, 560-million-kilometer cruise. During most of the cruise phase, RAD made detailed measurements of the cosmic ray (including SEPs and GCRs) radiation environment inside the spacecraft traveling through the space. The day after MSL's landing, RAD was switched back on and started making first-ever measurements of the cosmic ray induced energetic particle radiation environment on surface of Mars and has been collecting data for more than six years, approximately three years, since then. Both the deep-space radiation environment inside the spacecraft and the radiation field on Mars measured by RAD provide insight into the radiation hazards that be associated with a human mission to Mars and give indications of possible risk mitigation for future human explorations to the red planet.

    this talk, we review the RAD measurements since the launch of MSL and discuss the main results including (1) RAD measured cruise phase radiation environment and its (2) the Martian surface spectra and flux of energetic particles (both charged and neutral) detected by RAD and the validation of particle transport models based on these measurements, (3) the absorbed dose and dose equivalent rate from GCRs detected on Mars' surface and their time evolution influenced by both the atmospheric changes and heliospheric dynamics, and finally (4) the detected SEP events and their potential radiation risks.

  • 19.02.2019

    Prof. Dr. Friedrich Aumayr (TU Wien), abstract -  [Bonitz, Magnussen]
    "Probing 2D-materials by slow highly charged ions"

    Highly charged ions - along with femto- and attosecond light sources - provide a unique tool for probing the electronic response of solid materials to an extremely strong electric field, the Coulomb field of an approaching highly charged ion [1, 2]. In our experiments we study the ultrashort time response of different 2D-materials like graphene and MoS 2 to an incoming highly charged ion (typically Xe 40+ ). In a multi-coincidence setup [3] we measure the charge state and energy of highly charged ions transmitted through suspended 2D-membranes in coincidence with the number of emitted electrons. This allows us to derive the relevant time scales for charge transfer along the 2D-layer, the resulting current densities in the material and lower bounds for the breakdown currents. Depending on electron mobility some 2D materials fail to resupply the lost charges and/or fail to dissipate the absorbed energy on a timescale small compared to lattice vibrations. The resulting Coulomb explosion tears holes of the order of some nanometers into the 2D membrane [4], which are observed in high resolution (S)TEM investigations. The results of our studies are therefore of interest for engineering two-dimensional materials with electrons, ions, and lasers, with many prospective applications like their use as molecular sieves, for desalination or even DNA sequencing.

    [1] E. Gruber, et al., Nature Communications 7 (2016) 13948 (7 pages)
    [2] R. A. Wilhelm, et al. Physical Review Letters 119 (2017) 103401 (6 pages)
    [3] J. Schwestka, et al. Rev. Sci. Instrum. 89 (2018) 085101
    [4] R. A. Wilhelm, et al. 2D Materials 2 (2015) 035009 (6 pages)
    [5] R. A. Wilhelm, et al. Appl. Sci. 8 (2018) 1050 (16 pages)

Vorträge im SS 2019

"Moderne Anwendungen von Frequenzkämmen"

In den letzten Jahren hat sich der Frequenzkamm von einem reinen Hochpräzisions-Messinstrument zu einem vielseitigen Werkzeug in der Spektroskopie und der allgemeinen Messtechnik entwickelt. Die Genauigkeit und Robustheit moderner Frequenzkämme erlaubt nicht nur den Einsatz im wohltemperierten Optiklabor, sondern auch in raueren Umgebungen wie beispielsweise in Flugzeugen oder Raketen. In diesem Vortrag werden einige Anwendungen dieser neuen Frequenzkämme gezeigt, vom Uhrwerk für die genauesten optischen Atomuhren über Spektroskopie im Weltraum und der Erzeugung hochreiner Mikrowellenstrahlung bis hin zur hochauflösenden Molekül-Spektroskopie.

  • 02.04.2019
  • 09.04.2019

    Dr. Konstantin Herbst (Institut für Experimentelle und Angewandte Physik, CAU Kiel), abstract - [Heber]
    Exploring the Radiation and Particle Environment of G-, K-, and M-Stars and its Impact on (Exo)planetary Habitability"

    The search for life outside our solar system was, and still is, a significant motivator for the detection of extrasolar planets in the Habitable Zone (HZ) of other stellar systems. Since the first confirmation of an exoplanet orbiting a Sun-like (G-type) star in 1995, the existence of thousands of exoplanets has been confirmed, of which well over a dozen were detected within the HZ of their host stars. With upcoming missions like the James Webb Space Telescope (JWST), the European Extremely Large Telescope (E-ELT) and the Atmospheric Remote‐sensing Infrared Exoplanet Largesurvey (ARIEL) we soon will be on the verge to detect and characterize atmospheres of, i.e., rocky Earth-like exoplanets for the first time. Due to their much better detection probability, thereby, G-, K-, and M-dwarf stars are favored targets of upcoming missions.

    However, recent observations showed that the exoplanetary radiation environment around G-, K-, M-dwarf stars is much harsher compared to what we know from the Sun. Being located at small to its host star the Earth-like exoplanet is exposed to an enhanced stellar radiation environment, which could affect the habitability, e.g., in the form of a hazardous flux of energetic particles. Knowing the stellar radiation environment, and thus, being able to model the radiation exposure on the surface of a planet is crucial in order to assess its habitability.

    Of course, the only planetary system we can study in great detail is our own, the solar system. This talk will give an overview of what we know about the Sun and its impact on the planets of the solar system (i.e., Venus, Mars, and Earth), and how this knowledge can be used to determine the particle and radiation environment of G-, K-, and M-stars. Moreover, to investigate the impact of an active star on a potential planet in its HZ, we show our model efforts for the nearest stellar neighbor Proxima Centauri and its Earth-like exoplanet Proxima Centauri b.
  • 16.04.2019
  • 23.04.2019

    Prof. Dr. Klaus von Klitzing (Max-Planck-Institut für Festkörperforschung,Stuttgart), abstract - [Bonitz]
    "Max Planck, seine Konstante und das neue Kilogramm”

    Am 23.4.1858 erblickte der Kieler Ehrenbürger Max Planck das Licht der Welt. Das physikalische Kolloquium der CAU würdigt den Nobelpreisträger und Begründer der Quantentheorie an seinem diesjährigen Geburtstag mit einem besonderen Vortrag und Geburtstagsgeschenk: Die von Max Planck entdeckte und nach ihm benannte Naturkonstante h erhält einen für ewige Zeiten festgelegten Wert. Diese Festlegung wurde auf der Internationalen Generalkonferenz für Maß und Gewicht am 16.11.2018 in Versailles verabschiedet und soll ab 20.5.2019 als Basis für ein neues Kilogramm Anwendung finden.
    Der Vortrag gibt einen Überblick über die Bedeutung von Naturkonstanten für das ab 20.5.2019 weltweit gültige neue Einheitensystem. Dabei spielt der vom Vortragenden entdeckte Quanten Hall Effekt (Nobelpreis 1985) eine wesentliche Rolle.

  • 30.04.2019
  • 14.05.2019
  • 21.05.2019
  • 28.05.2019

    Dr. Martin Schrön,  UFZ Leipzig - Helmholtz Centre for Environmental Research GmbH, abstract [Heber]
    "Detecting Environmental Water with Ground Albedo Neutrons from Cosmic Rays"

    A few years ago, researchers found a way to detect water in the shallow ground with the help of exploding stars. The cosmic rays generated by supernova remnants can create neutrons near the planetary surface, which are highly sensitive to its hydrogen content. While this principle has been used to find water on Mars, researchers have developed the method further for applications on Earth in order to tackle current questions in hydrology, agriculture, and climate science.
    Conventional neutron monitors on Earth have been used for decades to track the dynamics of incoming cosmic-ray particles under the assumption that local environmental conditions do not influence the highly energetic signal. In contrast, the low-energy signal of reflected cosmic-ray neutrons
    can be used to monitor local conditions, particularly the surrounding water content. Water in soil, air, snow, and vegetation determines the number of ground albedo neutrons in the sensitive energy range from 1 eV to 100 keV. Specialized neutron detectors have been introduced in 2012 as the
    COsmic Ray Soil Moisture Observing System (COSMOS) and since that time, plenty of those instruments have been installed on natural or agricultural sites throughout the USA (>50), Europe (>80), Africa (>4), Asia (>2), and Australia (>5), and more to follow.
    Climate research, hydrologic models and irrigation management rely on large-scale soil moisture data. In contrast to conventional water sensors, the COSMOS products can represent root-zone water content averaged within an area of tens of hectares due to the fast diffusion of neutrons in air.
    However, many open questions regarding the physics of the signal are still to be solved, such as the modulation of the count rate by the dynamics of incoming cosmic rays. The talk presents recent developments in cosmic-ray neutron sensing and shows how hydrology, agricultural, and climate
    sciences can benefit from astro-particle physics.

  • 04.06.2019
  • 11.06.2019
  • 18.06.2019
  • 25.06.2019

    Prof. André Moitinho de Almeida, Lissabon, abstract [Duschl]
    "The Milky Way and Beyond
      Gaia - A New Age of Astrometry"

    The Universe is made of galaxies. It is thus clear that understanding how galaxies form and evolve is a central quest in astronomy. The galaxy in which we live, the Milky Way, is a giant spiral galaxy - a particularly interesting type. Being inside the Milky Way allows us to study details of its workings with a resolution unthinkable of for other galaxies. However, this super-detailed inside view also creates difficulties. On the one hand, it is hard to have a global perspective of the Milky Way (as we have for external galaxies). On the other hand, with the advent of large surveys by ground and space telescopes, we face the challenge of dealing with overwhelming quantities of data.
    In this talk, we will go on a trip through our current knowledge of the Milky Way and its big open questions: From our solar neighborhood with its streams of stars and bubbles caused by supernova explosions, to the giant black hole in the centre of our galaxy and the observations of two thousand million stars by the Gaia space mission for building an unprecedented map of the Milky Way and beyond.
  • 02.07.2019
  • 09.07.2019

    Dr. Wolfgang Hänsel, Menlo Systems GmbH, Martinsried, abstract [Harm]
    Moderne Anwendungen von Frequenzkämmen"

    In den letzten Jahren hat sich der Frequenzkamm von einem reinen Hochpräzisions-Messinstrument zu einem vielseitigen Werkzeug in der Spektroskopie und der allgemeinen Messtechnik entwickelt. Die Genauigkeit und Robustheit moderner Frequenzkämme erlaubt nicht nur den Einsatz im wohltemperierten Optiklabor, sondern auch in raueren Umgebungen wie beispielsweise in Flugzeugen oder Raketen. In diesem Vortrag werden einige Anwendungen dieser neuen Frequenzkämme gezeigt, vom Uhrwerk für die genauesten optischen Atomuhren über Spektroskopie im Weltraum und der Erzeugung hochreiner Mikrowellenstrahlung bis hin zur hochauflösenden Molekül-Spektroskopie.

  • 16.07.2019

    Dr. Gerhard Haase, Max Rubner-Institut Kiel (MRI), abstract [Steigies]
    "Monte-Carlo-Methode zur Bestimmung von Summations- und Selbstabsorptionsfaktoren in der Gammaspektrometrie und die Bewertung von Umweltradioaktivitätsmesswerten"

    Die Leitstelle zur Überwachung der Umweltradioaktivität für Boden, Bewuchs, Futtermittel und Nahrungsmittel pflanzlicher und tierischer Herkunft ist am Max Rubner-Institut (MRI), dem Bundesforschungsinstitut für Ernährung und Lebensmittel und dem dortigen Institut für Sicherheit und Qualität bei Milch und Fisch angegliedert. Die Leitstelle betreibt Forschung auf dem Gebiet der Radioökologie der Nahrungskette, führt Vergleichsanalysen durch, entwickelt neue Probenahme-, Analyse- und Messverfahren. Im Rahmen der Forschung wurde eine Monte-Carlo-Methode entwickelt die Summations- und Selbstabsorptionskorrekturen in der Gammaspektrometrie ermittelt. Die Photonen werden zeitlich nicht getrennt und vom Detektor als ein Summenimpuls registriert, dass bedeutet die koinzidenten Photonen lassen sich ihrer Energie entsprechend nicht mehr in den betreffenden Einzellinien im Spektrum nachweisen. Prinzipiell kann diese Berechnung dadurch realisiert werden, dass die zurückgelegte Weglänge der Photonen im Detektor ermittelt wird und mit dem linearen Massenschwächungskoeffizienten für das entsprechende Detektormaterial gefaltet wird. Bei der gammaspektrometrischen Untersuchung von Umweltproben werden bei unterschiedlichen Dichten Selbstabsorptionskorrekturen nötig, die ebenfalls mit der Monte-Carlo-Methode berechnet werden können.
    Im Weiteren wird das „Integrierte Mess- und Informationssystem zur Überwachung der Umweltradioaktivität“ (IMIS) vorgestellt. Aufgabe von IMIS ist es, die Umwelt kontinuierlich zu überwachen, um schnell und zuverlässig bereits geringfügige Änderungen der Radioaktivität in der Umwelt flächendeckend zuerkennen sowie langfristige Trends erfassen zu können. IMIS ist vor allem für eine schnelle Erfassung der radiologischen Lage in einer Notfallsituation ausgelegt. Hier sind die Leitstellen zukünftig gefordert ein rechnergestütztes Verfahren zu entwickeln, das die erfassten Umweltradioaktivitätsmesswerte der Landesmessstellen beurteilen kann.

Vorträge im WS 2019/2020

  • 15.10.2019

  • 22.10.2019

  • 29.10.2019: Prof. Dr. Nahid Talebi (IEAP, Universität Kiel)

    Titel: Nanooptics with Slow and Fast Electrons (Antrittsvorlesung)

    Abstract: Electron-light interactions and the various mechanisms lying within this context have been discussed from the very early days of the rise of quantum mechanics. Transition from classical concepts such as Thomson scattering to more advanced quantum mechanical counterparts like Compton scattering, photoelectric effect, and more recently free-electron lasers, opened the way towards designing precise accelerating mechanisms and radiation sources.

    Here, I first discuss electron-light interactions from the classical point of view. Mainly, inelastic interaction of electron beams with optical near-field distributions in nanostructures is considered. I show that near-field distributions can act as a mediator to transfer the energy between electron beams and light [1]. Moreover, based on the contribution of the electron-induced polarization to the radiation continuum, few-photon radiation sources are proposed and investigated [2]. Moreover, thin film electron-driven photon sources can be employed inside electron microscopes, for the purpose of spectral interferometry [3].

    In a second part of my talk, I discuss electron-light interactions from semi-classical standpoint. First, I investigate the free-space interaction and consider the generalization of Kapitza-Dirac effect (KDE) to address quantum-coherent phenomena which occur as a result of interference between ponderomotive and absorptive/emissive parts of the minimal coupling Hamiltonian [4]. Then, I talk about the interaction of point-projection slow-electron wavepackets with light and nanostructures [5]. It is shown that the coupling strength between electrons and near-field light is increased by decreasing the electron velocity; hence this fact demonstrates the sensitivity of slow electrons to the electromagnetic interactions, covering both elastic and inelastic scattering.

    [1] N Talebi, J. Opt. 19 (2017), 103001.
    [2] N Talebi, S Meuret, S Guo, M Hentschel, A Polman, H Giessen, et al., Nat. Commun. 10 (2019), 599.
    [3] N Talebi, Sci. Rep. 6 (2016), 33874.
    [4] N Talebi and C Lienau, "Interference between Quantum Paths in Coherent Kapitza-Dirac Effect," New J. Phys. 21 (2019), 093016
    [5] J Vogelsang, N Talebi, G Hergert, A Wöste, P Groß, A Hartschuh, et al., ACS Photon. 5 (2018), 3584.

    Gastgeber: Prof. Magnussen
  • 05.11.2019: (Fest-) Kolloquium Satellit Azur - Vortrag: Dr. Berndt Klecker, Max Planck Institut für extraterrestrische Physik, Garching

    Titel: Energiereiche Teilchen in der Magnetosphäre: Erkenntnisse von AZUR bis zu den Van Allen Probes

    Abstract: Vor nunmehr 50 Jahren, am 8. November 1969, wurde der erste deutsche Forschungssa-tellit (AZUR) gestartet. Etwa zehn Jahre vorher waren mit den ersten US amerikanischen Satelliten Explorer 1 und 3 (1958) energetische Teilchen in der Magnetosphäre der Erde entdeckt worden, und damit die Strahlungsgürtel der Erde, die später zu Ehren des Ent-deckers „Van Allen Strahlungsgürtel“ genannt wurden. Die Aufgabe von AZUR war es, mit einer Reihe von Sensoren (Magnetometer, Photometer, Teilchendetektoren) diese Strahlungsgürtel, sowie die Polarlichtzone und solare Teilchenereignisse näher zu er-kunden. Die Instrumentierung und der Satellit wurden in Zusammenarbeit mehrerer In-stitute in Deutschland (MPE, CAU, MPAe, TUB, DFVLR) und der Industrie (Hauptauf-tragnehmer Bölkow) entwickelt und mit einer Scout Rakete in Vandenberg (USA) gestartet.

    AZUR markiert somit den Beginn der Weltraumforschung in Deutschland, die in den folgenden Jahrzehnten einen stürmischen Aufschwung erlebte. Seither wurden weltweit zahlreiche wissenschaftliche Satelliten zur Erforschung der Magnetosphäre der Erde gestartet. Im ersten Teil des Vortrags werde ich zunächst einen Überblick über die Mission AZUR, deren Ergebnisse, sowie die Strahlungsgürtel der Erde geben. Im zweiten Teil folgt dann eine Übersicht der weiteren Entwicklung mit einigen Höhepunkten, die mit Missionen wie ISEE-1/2 (Start 1977), AMPTE (Start 1984), SAMPEX (Start 1992), Cluster (Start 2000) und van Allen Probes (Start 2012) verbunden sind.

    Gastgeber: Prof. Heber
  • 12.11.2019: Prof. Arutiun Ehiasarian (Sheffield Hallam Universiity, UK)

    Titel: High Power Impulse Magnetron Sputtering: The Age of Adolescence

    Abstract: High Power Impulse Magnetron Sputtering (HIPIMS) is a technology for the deposition of thin films using large volumes of dense plasma. The growth of films in such an environment benefits from a greatly enhanced degree of freedom of the system which diversifies the reactions in the plasma phase and opens unique pathways for film formation and tailor-ing film properties. To achieve this, plasma generation is carried out at significantly higher instantaneous power than conventional sputtering methods. The power is delivered in pulses on timescales that are sufficient to produce dense metal plasma of 1013 cm-3 whilst avoiding heat buildup and transitions from glow to arc discharge on the target. In par-ticular regimes, the plasma self-organises into waves which propagate in the E×B direction and build up localised plasma density spikes that shield the confining fields and increase pressure to generate intense particle emission in direction to the substrate.

    Metallic plasmas containing rare earth ions were used to produce an implantation zone of a few nanometres to seal and protect the surface of substrates against oxidation. They also served to promote adhesion by providing conditions for local epitaxial growth inducing a crystalline interface and chemistry for better wetting during film nucleation.

    For metallic films of Mo, the ratio of double- to single- charged metal ions could be varied in a wide range through the peak current and charge exchange reactions with the process gas. The ratio correlated with the grain size and im-proved smoothness of the films due to the additional energy gained by the higher charge states through the sheath. It also shifted the crystallographic orientation from a highly textured to a random mix. ErNi films have improved crystallin-ity and heat lift capacity at cryogenic temperatures whilst Nb films have better superconducting properties. Better coverage of meshes and high aspect ratio vias is achieved.

    In reactive sputtering conditions, the deposition flux comprises mainly ions of metal and dissociated nitrogen which change the dynamics of adatoms on the surface and promotes a (200) crystallographic texture which in turn sustains fully dense column boundaries in TiN monolithic films.

    Nanolayered CrN/NbN and CrAlN/CrN developed with low waviness and enhanced density making them suitable for corrosion, wear, biological and high-temperature oxidation environments. Nanocomposites of CrAlN-SiN can be pro-duced with different cluster size and corresponding hardness.

    The deposition of oxides has benefited from controlling the current in the discharge pulse to produce high density TiO2 films for architectural glass coatings and enabling the production of highly insulating materials such as SiO2 for the glass and semiconductor industries.

    Industrial uptake is rife in the fields of hard coatings and microelectronics with a number of vendors providing turn-key solutions.

    Gastgeber: Prof. Kersten
  • 19.11.2019: Dr. Jingnan Guo (Habilitationsvorlesung)

    Titel: Gravitational waves and how scientists found them

    Originally proposed by Henri Poincaré in 1905 and pridicted by Albert Einstein in 1916 in his general theory of relativity, graviational waves are generated by some of the most violent and energetic processes in the Universe and spread like 'ripples' throughout space-time. Massive accelerating objects such as neutron stars and black holes orbiting and even colliding into each other disrupt space-time in such a way that these waves of distorted space-time would radiate outward from the source.  These ripples travel at the speed of light through the Universe, carrying with them information about their origins as well as clues to the nature of gravity itself. However, it took nearly a century until gravitational waves were first directly detected by the Laser Interferometer Gravitational-wave Observatory (LIGO) in September of 2015. In this lecture, I will give an overview of the basic principle, challenge, and data processing for the detection of gravitational waves.

    Gastgeber: Prof. Wimmer-Schweingruber
  • 26.11.2019: Prof. Dr. K.A.H. van Leeuwen (Eindhoven School of Education)

    Titel: New tools for electron microscopy

    Abstract: Electron microscopes have developed into extremely powerful and versatile tools for research in physics, chemistry, biology, and material science. Although around since 1931 and very well developed by now, efforts to extend the usability even further are still fierce and fast-progressing. Examples are the development of ultrafast electron microscopy, which allows the study of dynamical processes on a very short timescale, combining EELS (electron energy loss spectroscopy) with electron microscopy in order to image material composition, and extending phase-contrast (Zernike) microscopy to the electron domain, which enables the imaging of non-absorbing objects. In this talk I will discuss novel devices for electron microscopy based on microwave cavities as well as the ponderomotive interaction with pulsed laser beams. Microwave cavities allow extensive phase space manipulation of electron beams, with applications in ultrafast and in EELS microscopy. Using the ponderomotive interaction, the actual phase of the quantum mechanical electron wavefunction can be manipulated. The latter has a direct application as an (immaterial) phase plate for Zernike phase contrast microscopy, but also opens a wider range of options in diffractive and interferometric optics with electrons. The Eindhoven CQT group (headed by prof. Jom Luiten) collaborates with prof. Nahid Talebi in the ponderomotive project.

    Gastgeber: Prof. Talebi
  • 03.12.2019: Prof. Dr. Elke Scheer (Universität Konstanz)

    Titel: Visualization of spatial modulation and persistent response states of strongly-driven membrane resonators

    Abstract: Micro- and nano-scale mechanical resonators operated in the strongly nonlinear regime exhibit unusual dynamic behavior, including the phenomenon of persistent response, which denotes the development of a vibrating state with nearly constant and high amplitude over a wide frequency range. The origin of this persistent response state can be revealed for membrane resonators by optical profilometry. By applying a combination of temporally and spatially resolved methods we show that the rectangular membrane adopts a peculiar ring-shaped pattern I which different parts of the membrane oscillate at different frequencies, a phenomenon that we denote as spatial modulation [1]. At even larger driving strength, the persistent response arises as a signature of mode coupling between different flexural modes and their localized overtones.


    Finally, we propose a phase diagram for the manifold vibrational states that the membrane can adopt and a model based on the coupling of nonlinear oscillators that qualitatively describes the experimental observations.

    [1] F. Yang et al., Phys. Rev. Lett. 122, 154301 (2019)

    Gastgeber: Prof. Berndt
  • 10.12.2019: Dr. Franko Greiner (IEAP)

    Titel: From dust in plasma to (nano) dusty plasma

    Abstract: The physics of dusty plasmas is a relatively new field of plasma physics. It has its origins in extra-terrestrial and plasma technological research. The research field of dusty plasmas grew significantly triggered by the first creation of dust crystals in the laboratory in the mid-nineties. After a first phase of discovery, a lot of initial adapted experimental techniques and accompanying theoretical models were developed. Since then research demanded more and more for high precision diagnostics and methods. Researchers of the plasma physics department at Kiel University have actively participated on this development from the very beginning including the analysis of dust crystals, single particles, particles as plasma probes, particle chains, Yukawa balls and microparticle clouds under microgravity conditions. Within the last years the fundamental physics of billions of nanoparticles produced and confined in a nano-dusty plasma (see figure) became a new hot topic in the field. This talk presents the current status and future perspectives of nanodust diagnostics with special emphasis on novel diagnostics like imaging Mie ellipsometry and dust density wave diagnostics.


    Gastgeber: Prof. Benedikt
  • 17.12.2019: Dr. Dominik Kraus (Helmholtz-Zentrum Dresden-

    Titel: Warm Dense Matter: From Giant Planets and Stars to Nanoparticles

    Abstract: The interiors of planets and stars exhibit extreme conditions: High temperatures and enormous pressures create environments which are not fully understood and hard to en-compass for state-of-the-art physics models. Applying the largest and most brilliant laser light sources, it is now possible to investigate such conditions in the laboratory. Recent efforts provide seminal insights into chemistry and phase transitions occurring deep in-side giant planets and elucidate the electronic structure of elements in the interiors of brown dwarfs and stars. At the same time, highly interesting materials can be formed via these conditions, such as nanodiamonds or hexagonal diamond, so-called lonsdaleite, which, in its pure form, is predicted to exceed the hardness of cubic diamond. Finally, the applied methods also allow for testing the response of materials at extreme conditions and ultrafast timescales. I will present a showcase of recent experiments investigating these topics and provide an outlook for future developments.

    Gastgeber: Prof. Bonitz
  • 07.01.2020: Dr. Sophie Meuret (CNRS France)

    Titel: Time resolved Cathodoluminescence from lifetime measurements to pump-probe luminescence

    Abstract: Cathodoluminescence has become one of the most powerful technique to study the optical proper-ties of nanostructures at the nanoscale. With the development of a pulsed electron beam, it is now possible to access dynamical information. In the case of nanophotonic structures, time-resolved cathodoluminescence [1] has significantly broaden the accessible optical properties, reaching an almost full characterization of their emission properties at the nanoscale. For example, it is able to measure the lifetime of excited states [2] or the speed of the diffusion of charge carriers [3]. How-ever, we are still unable to assess the influence of electron excitation on the nanostructure optical properties or to measure the local absorption properties of light. In this presentation we will show that pump-probe luminescence experiment has allow us to go beyond standard time-resolved ca-thodoluminescence measurement. In pump-probe luminescence, a pulsed electron beam and a pulsed laser beam excite the sample with a controlled delay between the two excitations, and we collect both the cathodoluminescence and photoluminescence signals. In a pump-probe experi-ment, we observed the relative change of the luminescence spectrum when both light and electrons illuminate the sample compared to when only one or the other is present. I will show how, thanks to this experiment, we can measure, at the nanoscale, the effect of electron interaction on the optical material properties (quenching or enhancement) [4] and the local light absorption properties.

    [1] M. Merano et al., Nature, vol. 438, no. 7067, pp. 479–82, Nov. 2005.
    [2] P. Corfdir et al., J. Appl. Phys., vol. 105, no. 4, p. 043102, 2009.
    [3] M. Shahmohammad et al, Appl. Phys. Lett., vol. 107, no. 14, p. 141101, 2015.
    [4] M. Solà-Garcia et al, ACS Photonics, asap, (2019)

    Gastgeber: Prof. Talebi
  • 14.01.2020: Prof. Antti-Pekka Jauho (DTU Copenhagen)

    Titel: Quantum transport in nanostructured graphene

    Abstract: Ballistic and quantum effects are often suppressed in nanostructured graphene due to disorder effects. With careful sample preparation, however, spectacular effects can be observed and modelled with quantita-tive agreement. In this talk, I describe three such cases. The first one is a theoretical prediction – yet to be realized, but the next two are jointly carried out be experimentalists and theorists, and a very satisfactory agreement is achieved between theory and experiment. (1) A nonplanar sheet of graphene may exhibit “pseudomagnetic” fields. The two inequivalent valleys in the band structure of graphene couple differently to a pseudomagnetic field suggesting the possibility of manipulating the valley index (valleytronics) with the pseudomagnetic fields. I describe a recent suggestion utilizing these ideas based on bubbles in a graphene sheet [1]. (2) Graphene nanowires, formed at the step edges of a SiC crystal, can display exceptional ballis-tic transport [2]. In recent experiments, in a multiprobe STM setup, spatially resolved measurements can probe the details of the conductance channels, thus putting these useful theoretical concepts on a firm ex-perimental basis. I describe these measurements, and their detailed modelling, which agree in quantitative detail [3]. (3) Commensurality oscillations may occur in magnetotransport in periodically modulated two-dimensional systems. The challenge for graphene based systems has been the fabrication of sufficiently tight and regular superlattices. Recently it has been realized that encapsulating the graphene layer between hBN layers first, and only subsequently applying the ebeam-assisted etching to fabricate the periodic lat-tice, leads to sufficiently regular structures where these quantum effects can be observed [4].

    The work at CNG is supported by Danish National Research Foundation, Project DNRF103.

    [1] M. Settnes et al., “Graphene nanobubbles as valley filters and beam splitters”, Phys. Rev. Lett. 117, 276801 (2016)
    [2] J. Baringhaus et al., “Exceptional ballistic transport in epitaxial graphene nanoribbons”, Nature 506, 349 (2014)
    [3] J. Aprojanz et al., “Ballistic tracks in graphene nanoribbons”, Nature Communications 9, 4426 (2018)
    [4] B. S. Jessen et al., “Lithographic band structure engineering of graphene”, Nature Nanotechnology 14, 340 (2019)

    Gastgeber: Prof. Bonitz
  • 21.01.2020: Prof. Dr. Harald Brune (EPFL, Lausanne)

    Titel: The Magnetism of Single Surface Adsorbed Atoms – Recent Achievements and Future Perspectives

    Abstract: The ultimate size limit of a magnetic bit is a single atom. Despite long lasting research efforts of several groups, and despite the spectacularly large orbital moments and anisotropy energies reported on single surface adsorbed atoms, all investigated systems were paramagnetic down to lowest temperatures. This changed in 2016, where two systems with magnetic remanence were identified. We report on these systems where indeed single atoms are stable magnets. We show how their magnetization can be read and written and we elaborate on the mechanisms that limit their stability. These involve electron and phonon scattering, but also the interaction between electron and nuclear spins. Our results show that single atom magnetic information storage is feasible with coercitive fields and temperatures that outperform the best molecular magnets. We discuss the features that need to be met for single atom magnetic quantum bits, i.e., for single atoms that enable coherent manipulation of the wave function describing their magnetic quantum state.

    Gastgeber: Prof. Berndt
  • 28.01.2020: Prof. Dr. Edvin Lundgren (Lund University)

    Titel: Operando high energy surface x-ray diffraction studies of model catalysts and electrodes

    Abstract: Catalysis is an important process and is widely applied on an industrial scale for a large number of applications in either gas or in liquid phase. Industrial catalysts are complex materials, and as a consequence the gas/liquid-surface interaction between simplified single crystal surfaces and molecules in controlled environments has been studied for decades. We have in recent years explored the possibilities to perform experiments at conditions closer to those of a technical catalyst, in particular at elevated pressures and in an electrolyte. In this contribution, recent results using High Energy Surface X-Ray Diffraction (HESXRD) [1] combined with other in situ techniques [2-4] will be presented. Armed with structural knowledge from ultra-high vacuum experiments, the gas or electrolyte induced structures can be identified, and related to changes in the reactivity. The strength and weaknesses of the experimental techniques will be discussed.

    [1] J. Gustafson et al; Science 343 (2014) 758.
    [2] S. Blomberg et al; Phys. Rev. Lett. 110 (2013) 117601.
    [3] J. Zetterberg et al; Nat. Comm. 6 (2015) 7076.
    [4] W. Linpé et al; Submitted

    Image Lundgren

    Edvin Lundgren is a professor at the physics institute at Lund University, Sweden. Lundgren received his PhD at Lund University 1996 and spent 2 years at the ESRF, France and 3 years at TU-Wien, Austria before returning to Lund. His research is focused on surface structures on the atomic scale and applying in situ synchrotron-based techniques to material systems under working conditions. The research has led to the discovery of a new set of ultrathin oxides on late transition metals, atomic scale views on nano structures such as quantum dot and nanowire surfaces and novel work on in situ studies of model catalysts and electrodes at work.

    Gastgeber: Prof. Magnussen
  • 04.02.2020: Prof. Dr. Beatriz Roldán Cuenya (Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin)

    Titel: Insight into CO2 Electroreduction through rational Catalyst and Electrolyte Design

    Abstract: The utilization of fossil fuels as the main energy source gives rise to serious environmental issues, including global warming caused by the continuously increasing level of atmospheric CO2. Recently, the electrochemical conversion of CO2 (CO2RR) to chemicals and fuels driven by electricity derived from renewable energy has been recognized as a promising strategy towards sustainable energy.

    I will provide examples of recent advances in the development of highly active plasma-modified single crystals, nanostructured thin films and nanoparticle (NP) electrocatalysts (Cu, Ag, Zn, and Cu-M with M = Zn, Sn) and how their structure (crystal orientation, atomic arrangement, size, shape, defects,…), oxidation state and composition influence their selectivity in CO2RR. I will also discuss how important morphological motives and chemical sites can be created and regenerated in pulsed electrochemistry experiments. Additionally, the determining role of the electrolyte in the surface restructuring, reaction activity and selectivity will be illustrated. Finally, the importance of in situ and operando characterization methods (e.g. EC-AFM, Liquid-TEM, XAS, XPS, XRD) to gain in depth understanding on the structure- and electrolyte-sensitivity of real CO2RR catalysts under working conditions will be demonstrated. Our results are expected to open up new routes for the reutilization of CO2 through its direct selective conversion into higher value products such as ethylene and ethanol.

    Gastgeber: Prof. Magnussen
  • 11.02.2020: Dr. rer. nat. Eike Hentschel (Universitätsbibliothek Kiel)

    Titel: Zentrale Finanzierung von Open Access in Zeitschriften über DEAL und Publikationsfonds der CAU

    Abstract: An der CAU stehen mittlerweile 3 Säulen zur zentralen Finanzierung von Publikationsgebühren für Open Access-Artikel in Zeitschriften zur Verfügung:

    1. Im Rahmen der DEAL-Verträge der CAU aktuell mit Wiley und voraussichtlich ab Januar 2020 mit SpringerNature können alle Wissenschaftler*innen der CAU ihre Artikel als corresponding authors in den meisten Zeitschriften dieser Verlage (Subskriptionszeitschriften und originäre OA-Zeitschriften) ohne eigene Kosten Open Access veröffentlichen. Dazu kann die Autorin / der Autor im Publikationsprozess bei einer Wiley- (und später SpringerNature-) Zeitschrift einfach die unter Hinweis auf DEAL angebotene Open Access-Option auswählen. Ein DEAL-Vertrag mit Elsevier wird weiterhin angestrebt, ist aber aktuell noch nicht in Sicht.
    2. Ebenfalls für alle Wissenschaftler*innen der CAU steht außerdem ab 2020 ein DFG-finanzierter Publikationsfonds bereit, um Publikationsgebühren bis zu 2.000 EUR für ihre Artikel als corresponding authors in originären Open Access-Zeitschriften außerhalb von Wiley und SpringerNature zu finanzieren.
    3. Darüber hinaus steht speziell für Nachwuchswissenschaftler*innen der CAU ein weiterer Publikationsfonds des Landes zur Verfügung, um Publikationsgebühren bis zu 2.000 EUR für ihre Artikel als corresponding authors in originären Open Access-Zeitschriften außerhalb von Wiley und SpringerNature zu finanzieren. Anträge für beide Fonds können über Web-Formulare bei der UB eingereicht werden.

    Weitere Informationen finden Sie unter: (unter dem Punkt Finanzierung)

    Gastgeber: Prof. Magnussen
  • 18.02.2020: Prof. van de Sanden (Direktor von DIFFER (Dutch Institute for Fundamental Energy Research), Eindhoven, NL)

    Titel: Recent trends in renewable energy driven chemistry for energy conversion and storage: plasma chemistry as the special case

    Abstract: In a circular CO2 neutral society, where the use of dense energy carriers based on carbon will still be needed, the re-use of (air captured) carbon dioxide is required. These dense energy carriers can be utilized to mitigate intermittency of renewable energy sources by providing seasonal storage, as feedstock for the chemical industry to replace fossil based feedstock and as green fuels for long haul and air transport. The use of electrons, from renewable electricity, or photons, directly from the sun, provide scientific and technologi-cal opportunities to develop novel pathways for chemical conversion. In this talk, after an introduction to the challenges facing the world in the next decades, I will discuss the op-portunities of using plasmas, powered by renewable electricity, for scalable gas conver-sion of key molecules such as CO2 and N2. In particular, I will address the use of micro-wave plasma to dissociate CO2 into CO and O2, and the possible, often claimed, role of nonequilibrium vibrational kinetics.

    Gastgeber: Prof. Benedikt

Physikalisches Kolloquium der Sektion Physik im Wintersemester 2020 / 2021

Termin: dienstags 16.15 (Videokonferenz).

Verantwortlich: Prof. Michael Bonitz






Das Kolloquium wird als Videokonferenz durchgeführt:
ZOOM Meeting ID: 889 1529 8048
Passcode: 429028


  • 10.11.2020: Prof. Fabio Caruso (ITAP, CAU Kiel)

    ** Antrittsvorlesung **

    Electronic-structure theory of two-dimensional quantum materials:
    from fundamental interactions to novel emergent phenomena

    Prof. Fabio Caruso

    A detailed understanding of the quantum-mechanical interactions between the constituents of matter holds the promise of driving the discovery of new functional materials and designing their properties. First-principles electronic-structure theory has evolved into a robust framework to address this challenge, as it allows to establish the inherent relationship between the macroscopic properties of solids and elementary interactions at the nano scale.

    In the Computational Solid-State Theory group, we develop and employ state-of-the-art first-principles approaches for the theoretical description of the electronic and vibrational properties of two-dimensional materials, such as graphene and transition-metal dichalcogenides. These compounds are characterized by a unique interplay of charge confinement, reduced dielectric screening, and strong light-matter coupling. This makes them prone to exhibit a rich spectrum of emergent phenomena, including charge-density waves, polarons, and circular dichroism. Through a few examples taken from our recent research activities, I will illustrate the predictive power achievable by means of modern first-principles techniques based on many-body perturbation theory in the description of these phenomena. I will further discuss how these activities relate and contribute to the open challenges in the field of electronic structure theory.

  • 17.11.2020: Prof. Philipp Werner (Uni Fribourg, CH)

    Nonequilibrium dynamical mean field theory
    Philipp Werner

    Recent experiments on laser-driven solids have revealed interesting nonequilibrium effects such as light-induced superconducting states [1,2] or switching into long-lived metastable states with different structures and electronic properties [3]. To investigate and understand such phenomena, new theoretical and computational tools need to be developed. I will present the dynamical mean field approach, which over the past 15 years has been extended into a powerful framework for the simulation of real-time dynamics in correlated lattice systems [4]. After introducing this nonequilibrium Green's function based technique, I will discuss benchmarks against cold-atom based quantum simulators [5], and present recent applications to laser-driven lattice models. These investigations demonstrate the possibility of effectively cooling correlated electron systems [6], and inducing magnetic, superconducting or excitonic order in long-lived nonequilibrium states. I will comment on the implications of these findings for the experiments on light-induced superconductivity.

    [1] S.Kaiser, C. R. Hunt, D. Nicoletti, W. Hu, I. Gierz, H. Y. Liu, M. Le Tacon, T. Loew, D. Haug, B. Keimer, and A. Cavalleri, Phys. Rev. B 89, 184516 (2014).
    [2] M. Mitrano, A. Cantaluppi, D. Nicoletti, S. Kaiser, A. Perucchi, S. Lupi, P. Di Pietro, D. Pontiroli, M. Ricco, S. R. Clark, D. Jaksch, and A. Cavalleri, Nature 530, 461 (2016).
    [3] L. Stojchevska, I. Vaskivskyi, T. Mertelj, P. Kusar, D. Svetin, S. Brazovskii, and D. Mihailovic, Science 344, 177 (2014).
    [4] H. Aoki, N. Tsuji, M. Eckstein, M. Kollar, T. Oka, and P. Werner, Rev. Mod. Phys. 86, 779 (2014).
    [5] K. Sandholzer, Y. Murakami, F. Goerg, J. Minguzzi, M. Messer, R. Desbuquois, M. Eckstein, P. Werner, and T. Esslinger, Phys. Rev. Lett. 123, 193602 (2019).
    [6] P. Werner, M. Eckstein, M. Mueller, and G. Refael, Nature Comm. 10, 5556 (2019).

    Einladender: Prof. Caruso

    A video of the colloquium is available upon request.
  • 24.11.2020: Prof. Bradley J. Siwick (McGill University Montreal)

    Structure and Dynamics with Ultrafast Electron Microscopes: Moving Beyond the Molecular Movie
    Bradley J. Siwick

    In this talk I will describe how combining ultrafast lasers and electron microscopes in novel ways makes it possible to directly ‘watch’ the time-evolving structure of condensed matter on the fastest timescales open to atomic motion.  By combining such measurements with complementary (and more conventional) spectroscopic probes one can develop structure-property relationships for materials under even very far from equilibrium conditions and explore how light can be used to control the properties of materials.

    I will give several examples of the remarkable new kinds of information that can be gleaned from such studies and describe how these opportunities emerge from the unique capabilities of the current generation of ultrafast electron microscopy instruments.  For example, in diffraction mode it is possible to identify and separate lattice structural changes from valence charge density redistribution in materials on the ultrafast timescale and to identify novel photoinduced phases that have no equilibrium analogs.   It is also possible to directly probe the strength of the coupling between electrons and phonons in materials across the entire Brillouin zone and to probe nonequilibrium phonon dynamics (or relaxation) in exquisite detail.  

    I will assume no familiarity with ultrafast lasers or electron microscopes.

    [1] Morrison et al Science 346 (2014) 445
    [2] Otto et al, PNAS, 116 (2019) 450
    [3] Stern et al, Phys. Rev. B 97 (2018) 165416
    [4] Rene de Cotret et al, Phys. Rev. B 100 (2019) 214115

    Einladender: Prof. Bauer
  • 08.12.2020: Prof. Ido Kaminer (Technion –­­ Israel Institute of Technology)

    Free-Electron Quantum Optics
    Ido Kaminer

    Research of cavity quantum electrodynamics (CQED) has enabled new capabilities in quantum optics, quantum computation, and various quantum technologies. So far, all the work in this field has included light interacting with bound-electron systems such as atoms, quantum dots, and quantum circuits. In contrast, free-electron systems enable fundamentally different physical phenomena, as their energy distribution is continuous and not discrete, and allow for tunable transitions and selection rules.

    We have developed a platform for studying free-electron CQED at the nanoscale and demonstrated it by observing coherent electron interaction with a photonic cavity for the first time. Our platform includes femtosecond lasers in an ultrafast transmission electron microscope, which created what is, in many respects, the most powerful nearfield optical microscope in the world today. We resolve photonic bandstructures as a function of energy, momentum, and polarization, simultaneously with capturing the spatial distribution of the photonic modes at deep-subwavelength resolution.

    These capabilities open new paths toward using free electrons as carriers of quantum information. As examples, we show how to create free-electron qubits and implement quantum gates with femtosecond lasers. We further show how to measure quantum decoherence in space and time using the free-electron quantum interactions. Such interactions also enable new avenues for tunable X-ray sources, as we demonstrate with theory and experiments.

    Einladende: Prof. Talebi

  • 15.12.2020: Prof. Dr. David Go (University of Notre Dame, USA)

    How Should We Think About Plasma-Catalysis? Insights from Experiments and Simulations David B. Go

    Plasma-catalysis is an emerging field of plasma science and engineering where non-equilibrium plasmas are coupled with catalytic materials to more effectively drive chemical reactions. The field holds significant promise, with the potential to overcome existing challenges for many industrially-relevant processes, such as the reforming of natural gas or the synthesis of ammonia. However, plasma-catalysis systems are extremely complex, consisting of a wide variety of chemical and physical processes that can both synergistically work together and function in opposition to each other. While plasma chemistry and catalysis are both well studied fields in their own right, when they are coupled, the question arises: How should we think about these systems?  That is, should we think about them as catalysis systems that are enhanced by a plasma or a plasma system that is enhanced by a catalyst? Or should we think about them in a completely different way?  

    At the University of Notre Dame, an interdisciplinary team with expertise in plasma science, catalysis, surface science, and atomistic modelling have been trying to answer these questions both at a fundamental level and for what they imply for engineering plasma-catalysis systems. This colloquium talk will present a holistic perspective on our team’s work in this area. I will discuss how our findings have shown how plasma-catalysis diverges from ‘conventional’ thermal catalysis, how plasmas can drive chemical conversion ‘beyond equilibrium’, and the evidence we have that molecular processes – rather than macroscopic effects – help drive these behavior. This talk will set the stage for understanding how to design both catalysts and reactor systems that capitalize on the non-equilibrium conditions in a plasma to enhance chemical conversion.

    Einladender: Prof. Benedikt

  • 12.01.2021: Prof. Dr. Mathieu Kociak (Université Paris Sud, France)

    Nanooptics in the electron microscope
    Prof. M. Kociak

    Hunting optical phenomena at the nanometer scale, namely performing nanooptics, is paradoxical. On the one hand, the typical length-scale relevant for optics is of the order of a visible radiation wavelength: few hundred of nanometers. On the other hand, optical properties of nano-objects become to depart from bulk properties when the nano-objects become smaller than a few hundred of nanometers. In this case, the optical properties depend on minute variations of the size and shape of the nano-objects, and sometimes the morphology or structure of nano-objects have to be known with atomic resolution. Therefore, techniques that are not limited by the optical diffraction limit have been developed in the last 15 years to make possible to study novel optical nanomaterials and the novel physics they brought.

    In this talk, I will present the use of free electron beams – such as delivered in a transmission electron microscope – to perform optical spectroscopy at the nanometer scale. I will show how they can be used to map phonons, plasmons and excitons with unbeatable spatial resolution, and even in 3D. Beyond their impressive success in generating nice images, I will show how it is now possible to quantitatively understand such experiments in pure optical terms, such as extinction and scattering cross-sections or electromagnetic local density of states. I will also emphasize recent developments in ultra-high spectral resolution that makes it possible to tackle new field of nanooptics, such as the study of strong coupling between plasmons and excitons or phonons.

    Einladende: Prof. Talebi

  • 19.01.2021: Prof. Dr. Alexander Ako Khajetoorians (Radboud University, Netherlands)

    What can we “learn” from atoms?Prof. Dr. Alexander Ako Khajetoorians

    In machine learning, energy-based models are rooted in concepts common to magnetism, like the Ising model. Within these models, plasticity, learning, and ultimately pattern recognition can be linked to the dynamics of coupled spin ensembles that exhibit complex energy landscapes akin to behavior seen in spin glasses. While this behavior is commercially emulated in software, there are strong pursuits to implement these concepts directly and autonomously in solid-state materials. To date, hybrid approaches, which often use the serendipitous electric, magnetic, or optical response of materials, emulate machine learning functionality with the help of external computers. Yet, there is still no clear understanding of how to create machine learning functionality from fundamental physical concepts in materials, like hysteresis, glassiness, or spin dynamics. This motivates new fundamental investigations of complex spin systems, and how their behavior can be manipulated to potentially new paradigms.

    Based on scanning tunneling microscopy, magnetic atoms and films on surfaces have become a model playground to understand and design magnetic order. However, these model systems historically have been probed in limits for robust memory applications, namely strong double-well regimes. In this talk, I will illustrate new model platforms to realize machine learning functionality directly in the dynamics of coupled spin ensembles that exhibit multi-modal landscapes. I will first review the concept of energy- based neural networks and how they are linked to the physics of spin glasses. I will then highlight new examples based on the recent discovery of the so-called spin Q glass and the atomic Boltzmann machine. I will illustrate the creation of atomic-scale neurons and synapses, in addition to new learning concepts based on the separation of time scales and self-adaptive behavior. I will also discuss recent cutting-edge developments that enable magnetic characterization in new extreme limits and how this platform may be applied toward autonomous adaption and quantum machine learning.

    Einladender: Prof. Heinze

  • 26.01.2021: Dr. Hanno Kählert (ITAP, CAU Kiel)

    ** Antrittsvorlesung **

    Theory and simulation of strongly correlated plasmas and dense matter

    High density plasmas are fundamentally different from their low density counterparts in space or high temperature fusion reactors. Strong interactions give rise to novel phenomena such as liquid-like ordering and affect their thermodynamic and transport properties. The latter are important for the modeling of dense plasmas in inertial confinement fusion or warm dense matter in planetary interiors. Similar conditions occur at low temperatures or when highly charged ions are involved, which makes it possible to study strong coupling physics on a smaller scale with laser-cooled plasmas or charged dust particles. This talk gives an introduction to the physics of strongly correlated plasmas, their occurrence, and theoretical description. In particular, simulation methods have become indispensable tools to obtain reliable data for their properties in a regime where traditional plasma theory fails. As an example, I present results for the dynamic structure factor - a key quantity that is accessible experimentally and provides deep insight into the thermodynamic, transport, and dielectric properties of strongly correlated plasmas. Future challenges and possible directions for the field will be addressed.

Physics colloquium in the summer semester 2021

Date: Tuesdays 16.15 (video conference)

Responsible persons: Prof. Nahid Talebi, Prof. Jan Benedikt

Zoom access link




The colloquium will be held as a video conference:
ZOOM Meeting ID: 623 3676 8390
Passcode: 317082

  • 17.08.2021: Dr. Konstantin Linus Herbst, CAU

    Habilitationsverfahren, Probevorlesung: Wechselhafte Geisterteilchen - Neutrinos und ihre Tücken

    Dr. Konstantin HerbstDer Name Wolfgang Pauli ist untrennbar mit der bahnbrechenden Hypothese von der Existenz des Neutrinos verbunden. Ausgangspunkt für Pauli war das "kontinuierliche Energiespektrum" der Betastrahlen, das sich theoretisch nicht deuten ließ. Niels Bohr versuchte es mit der Hypothese von der "eingeschränkten Gültigkeit des Energieerhaltungssatzes”, was Pauli nicht akzeptieren konnte. So entwickelte Pauli die Idee, dass beim Betazerfall außer dem Elektron ein weiteres, aber elektrisch neutrales Teilchen - das Neutrino - emittiert wird, derart, dass die Summe der Energien der beiden Teilchen konstant ist. Es vergingen 26 Jahre zwischen der Vorstellung seiner Idee und dem Nachweis der Neutrinos. Heute wissen wir, dass sie fast nichts wiegen, dass sie Materie so gut wie ungehindert durchdringen und das sie Elementarteilchen ohne Ladung und damit nur schwacher Wechselwirkung sind. Zudem besitzen Neutrinos äußerst ungewöhnliche, quantenphysikalische Eigenschaften, welche sich beispielsweise in den Neutrinooszillationen - also der Umwandlung von einer Art in die andere - manifestieren. Ziel dieses Vortrages ist es, zu beleuchten, wie sich diese Quanteneffekte äußern, zu klären, was das mit der Masse der Teilchen zu tun hat und zu untersuchen, wieso Wissenschaftler auf der Suche nach Antworten zum Südpol fahren.

  • 04.05.2021: Prof. Dr. Claudia Draxl (Humboldt-Universität zu Berlin)

    From physics today to publishing and research of tomorrow

    Prof. Claudia DraxlThe growth of data from simulations and experiments is expanding beyond a level that is addressable by established scientific methods. The so-called “4 V challenge” of Big Data –Volume (the amount of data), Variety (the heterogeneity of form and meaning of data), Velocity (the rate at which data may change or new data arrive), and Veracity (uncertainty of quality) – is clearly becoming eminent also in the sciences. Controlling our data, sets the stage for explorations and discoveries. Novel artificial-intelligence tools can find patterns and correlations in data that cannot be obtained from individual calculations / experiments and not even from high-throughput studies. Prerequisites for the ultimate success of data-centric research are a change of our publication culture as well as a FAIR (Finable, Accessible, Interoperable, Re-useable) infrastructure, hosting data from sample synthesis, experiment, as well as theory and computations. I will review the concepts and recent progress of data-driven materials science, addressing the FAIR guiding principles, the importance of Open Data, issues of data quality, and examples of how to turn data into knowledge.

    Inviting person: Prof. Caruso

  • 11.05.2021: Prof. Dr Fabrizio Carbone (École Polytechnique Fédérale de Lausanne)

    Light-Induced phase transitions in strongly correlated systems

    Prof. Fabrizio CarboneUltrashort light pulses offer the possibility to create coherent excitations in solids which evolution can alter the path taken by the material across a phase transition. This can lead to the discovery of exotic out of equilibrium states of matter, and it can provide a unique way to disentangle the different degrees of freedom involved in a phase transition. In this seminar, we will review some recent results obtained by means of ultrafast spectroscopies in strongly correlated systems with a focus on high-temperature superconductors and the prototypical transition metal oxides magnetite and VO2.

    Inviting person: Prof. Talebi

  • 18.05.2021: Prof. Dr. Achim von Keudell (Ruhr-University Bochum)

    Transient atmospheric plasmas – mastering the nonequilibrium

    Prof. Dr. Achim von keudellNon equilibrium atmospheric plasmas form the unique basis for a multitude of applications ranging from thin films, surface modification, plasma chemistry to plasma medicine. In all these cases atmospheric pressure plasmas exhibit an intimate coupling to the bounding surfaces that trigger surface and conversion processes. The complexity of these processes makes a detailed understanding very challenging. Prominent examples are the combination of plasmas and catalysis and of plasmas and electrolysis. Plasmas provide either excited species to change the conversion reaction paths or they alter and may regenerate catalytic surfaces. The analysis requires detailed diagnostics of plasma excitation and surface processes at the plasma-solid or the plasma-liquid-solid interfaces. Three examples are being presented: (i) the conversion of CO2 and of volatile organic compounds is studied in atmospheric pressure plasmas revealing a strong non equilibrium with respect to excitation temperatures and plasma dynamics; (ii) the conversion of water by plasma excitation using nanosecond high voltage pulses that trigger extremely high density plasmas that are governed by field effects at the interfaces and by tunneling in between adjacent water molecules during plasma propagation; (iii) the plasma induced triggering of enzyme driven species conversion in biocatalysis. The work is supported by the SFB 1316 “Transient atmospheric pressure plasmas – from plasmas to liquids to solids”

    Inviting person: Prof. Benedikt

  • 08.06.2021: Prof. Dr. Wolfgang Schleich (University Ulm)

    Quantum carpets: A tool to observe decoherence

    Prof. Wolfgang SchleichQuantum carpets [1] - the spatio-temporal de Broglie density profiles- woven by an atom or an electron in the near-field region of a diffraction grating bring to light [2], in real time, the decoherence of each individual component of the interference term of the Wigner function characteristic of Schrödinger cats. The proposed experiments [2] are feasible with present-day technology.

    Quantum carpets

    [1] M. Berry, I. Marzoli, and W. Schleich, Quantum Carpets, Carpets of Light, Physics World 14, 39-44 (2001)
    [2] P. Kazemi, S. Chaturvedi, I. Marzoli, R.F. O’Connell, and W.P. Schleich, Quantum carpets - a tool to observe decoherence, New J. Phys. 15, 013052 (2013)

    Inviting person: Prof. Talebi

  • 15.06.2021: Dr. James McIver (Max Planck Institute for the Structure and Dynamics of Matter)
    Ultrafast optoelectronic probes of 2D materials

     Optoelectronic probes offer new opportunities for investigating quantum phenomena in 2D materials on ultrafast timescales and at terahertz frequencies. In this talk, I will report on our observation of a light-induced anomalous Hall effect in monolayer graphene driven by an intense femtosecond pulse of circularly polarized light [1]. We probed electrical transport using an ultrafast device architecture based on photoconductive switches. The dependence of the anomalous Hall effect on a gate potential used to tune the equilibrium Fermi level revealed multiple features that reflect a Floquet-engineered topological band structure [2], similar to the band structure originally proposed by Haldane [3]. This included an approximately 60 meV wide conductance plateau centered at the Dirac point, where a gap of equal magnitude was predicted to open. We found that when the Fermi level was tuned within this plateau, the estimated anomalous Hall conductance saturated around 1.8 ± 0.4 e^2/h.As an extended outlook, I will share our progress on using ultrafast optoelectronic circuits to perform near-field terahertz spectroscopy on graphene heterostructures, which could be used to investigate a wide range of topological and strongly correlated phenomena in 2D materials that often fall on the terahertz energy scale.

    [1] J.W. McIver et al. Nature Physics 16, 38 (2020)

    [2] T. Oka & H. Aoki. Phys. Rev. B 79, 081406 (2009)

    [3] F.D.M. Haldane, Phys. Rev. Lett. 61, 2015 (1988)

    Inviting person: Prof. Bauer

  • 22.06.2021: Prof. Dr. Günther Hasinger (Director of Science, ESA)

    The present and future of ESA's science program

    Exploring the Universe: Synergies and Strategies of the ESA Science Programme
    Science is THE underpinning theme of ESA. As the motor of the spiral of inspiration, innovation, infor-mation exchange and interaction with the Agency’s stakeholders, science is a key unifying theme of the Agency’s activities. Basic science drives innovation and therefore technological advances, lead¬ing to progress and economic development. It drives inspiration and thus the fascination and educa¬tion of new generations of scientists and engineers. It drives information exchange and communica¬tion with the general public that in the end as taxpayers fund the Agency. And it drives the interaction among scientists, with international partners and with stakeholders, ultimately leading to new pro¬jects and the next turn of the spiral. Starting from recent discoveries in astrophysics and space science I give a comprehensive summary of the ESA Science Programme. In particular I will give examples of important synergies between different ESA Science missions. I will also present the new strategic development plan Voyage 2050.

    Inviting person: Prof. Wimmer-Schweingruber

  • 29.06.2021, shifted starting time: 17:15 (!)
    Prof. Dr. Mark J. Kushner  (University of Michigan)

    Prof. Mark Kushner, University of MichiganPlasma 2020 – The US National Academies Decadal Assessment of Plasma Physics: Overview and Future Research Opportunities

    The Board on Physics and Astronomy of the United States (US) National Academies conducts every-10-year assessments of the major fields of physics. The purpose of the decadal assessments is to provide an overview of the progress made in the field over the past decade and to highlight research opportunities in the coming decade. The Plasma 2020 Decadal Assessment of plasma physics, Plasma Science: Enabling Technology, Sustainability, Security, and Exploration, was released in draft form in May 2020 and in final form in April 2021. The report broadly addresses the field of plasma physics, with chapters focused on foundational processes, laser-plasma interactions, high energy density systems, low temperature plasmas, magnetically confined fusion and space plasmas. The Plasma 2020 report, in addition to being a science document of interest to the international community, is also a policy document which responds to the charge of the sponsoring US federal agencies for recommendations on how plasma science should be configured and funded in the US. These agencies are the National Science Foundation, Department of Energy and Department of Defense. As a result, the F&R (findings and recommendations) of the report are US focused, while also hopefully being of interest to the international community by being adaptable to their particular administrative structures.
    In this presentation, an overview of the Plasma 2020 Decadal Assessment will be provided. The Decadal Assessment process will be briefly described, followed by highlights of the accomplishments, science opportunities and F&R across the field. More emphasis and detail will be provided for findings for low temperature plasmas.
    A (free) pdf copy of the Plasma 2020 Decadal Assessment can be downloaded here.

    Inviting persons: Prof. Benedikt, Prof. Kersten

  • 06.07.2021: Prof. Dr. Astrid Veronig, University of Graz (Head of Kanzelhöhe Observatory for Solar and Environmental Research)

    Solar and stellar mass ejections: detection and characterization through coronal dimmings

    Coronal mass ejections (CMEs) are magnetized clouds of plasma that are sporadically ejected by the star’s outer atmosphere and traverse interplanetary space with speeds of thousands of kilometers per second. Solar CMEs are the main source of strong space weather disturbances at Earth, due to the interaction of their magnetic fields and shock waves with the Earth’ magnetosphere. In addition, fast CMEs are often associated with radiation outbursts in the form of flares and high-energetic particle streams inducing further interactions with our planet. Stellar CMEs are supposed to have an even stronger impact on the exoplanets the star is hosting and may even pose a hazard to their habitability. While CMEs ejected by our Sun are regularly imaged by white-light coronagraphs that efficiently block the million-times brighter direct Sunlight, for stars this is not possible. Different approaches have been followed in the past to infer signatures of stellar CMEs, but so far, only few candidates for stellar CME detections are reported. Here we present a new approach, based on the sudden decrease in extreme-ultraviolet and X-ray emission caused by the mass loss during a CME, so-called coronal dimmings. We discuss the first dimming detections associated with flares on late-type stars, indicative for stellar CMEs, and relate them to the dimming-CME observations on the Sun.

    Inviting person: Prof. Heber