Physikalisches Kolloquium

Physics Colloquium at The Faculty of Mathematics and Natural Sciences

Lectures on tuesdays 16.15 in Hans-Geiger auditorium

Leibnizstr. 13, 24098 Kiel

Wintersemester 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)

     

Sommersemester 2019

 

  • 02.04.2019
  • 09.04.2019 - Dr. Konstantin Herbst (Institut für Experimentelle und Angewandte Physik, CAU Kiel) [Prof. Heber]
  • 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
  • 07.05.2019
  • 14.05.2019
  • 21.05.2019
  • 28.05.2019
  • 04.06.2019
  • 11.06.2019
  • 18.06.2019
  • 25.06.2019 - Prof. André Moitinho de Almeida (Lissabon) – Gaia – A New Age of Astrometry [Duschl]
  • 02.07.2019
  • 09.07.2019