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

Sommersemester 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

    free

  • 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
    free

  • 10.07.2018
    free

  • 17.07.2018
    free

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, IEAP,  Probevorlesung Habilitation
  • 15.01.2019 - Prof. Dr. Karsten Danzmann (MPI für Gravitationsphysik und Universität Hannover) - [Dau, Duschl]
  • 22.01.2019
  • 29.01.2019
  • 05.02.2019 - PD Dr. Horst Fichtner (Ruhr-Universität Bochum) - [Heber]
  • 19.02.2019 - Prof. Dr. Friedrich Aumayr (TU Wien) -  [Bonitz, Magnussen]