Microwavephysics and Atmospheric Physics
Biomedizinische Photonik
Ultrafast Science and Technology
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Last update: 13.09.2017
HS 2012: Seminare über Ultrafast Science and Technology
Thursday 11:15am
Vorträge, die innerhalb der nächsten Tage stattfinden, sind speziell markiert.
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Donnerstag, 16.08.2012

Prospects of THz Pulse Generation with mJ-Level Energy and 100 MV/cm Electric Field

Zeit: 10:15 Uhr
Hörsaal: B116
 
Dr. József A. Fülöp
University of Pécs
Hungary

A number of interesting application require single-cycle or near-single- cycle THz pulses with peak electric field strengths up to 100 MV/cm in the lower frequency part of the THz spectrum (around 1 THz). Our numerical and experimental studies indicate that optical rectification driven by efficient diode-pumped solid-state lasers, together with tilting the pump pulse front is a promising route towards the generation of such extremely intense THz pulses. Besides extending the scope of nonlinear THz spectroscopy, the foreseen applications range from attosecond physics to hadron therapy.

 
Donnerstag, 06.09.2012

Dry run of SWISS summer school talks:
(1) Plasma Homogenization for Overcoming Refractive Losses in X-ray Lasers
(2) Critical aspects for a XUV microscope

Zeit: 14:15 Uhr
Hörsaal: B116
 
(1) Leili Masoudnia
(2) Mabel Ruiz Lopez
Institute of Applied Physics
University of Bern

(1) Refractive losses along laser-produced plasmas used as gain media are caused by density gradients. The pump pulse is thus deflected from the high gain region and the short wavelength signal steers-away causing loss of collimation. Hollow cylinders used as targets make the plasma homogeneous and can mitigate refractive losses by means of wave-guiding.

(2) The aim of this presentation is to evaluate the principle aspects in order to define the “XUV microscope”. We first review the basic components and the objectives and condensers architecture. Afterwards we discuss the critical parameters used to define the microscope: contrast, resolution, aberrations and costs. Then, we will give an overview of the different of microscope types. The last part of the speech will be dedicated to the studies realized in our group to build an XUV microscope.

 
Donnerstag, 13.09.2012

Non-LTE Modeling for Laser-Driven Systems

Zeit: 10:15 Uhr
Hörsaal: B116
 
Dr. Howard Scott
Lawrence Livermore National Laboratory
Livermore, CA, USA

The capability to accurately model the properties of matter under non-local thermodynamic equilibrium (non-LTE) conditions is critical to the ability to understand a wide variety of laboratory and astrophysical plasmas. Non-LTE simulations have been used as a tool to understand laser-produced plasmas for several decades. Numerous projects now depend on non-LTE modeling as a design tool. Accordingly, considerable effort has gone into developing this capability, but significant challenges remain. Experiments in laser-driven inertial confinement fusion at the National Ignition Facility (NIF) have recently demonstrated plasma conditions approaching those required for ignition. Non-LTE modeling is a key part of the simulation effort, affecting several aspects of experimental design and diagnostics [1]. The X-rays that drive the capsule arise from high-Z material ablated off the hohlraum wall. Mid-Z dopants in the ablator provide shielding and diagnostic possibilities, but potentially impact the energy balance of the capsule [2]. Looking beyond the NIF, a proposed design for a fusion reactor chamber depends on low-density high-Z gas absorbing X-rays and particles to protect the first wall [3]. X-ray free electron lasers provide some unique capabilities in high energy density physics. The extremely intense pulses can produce plasmas on short enough timescales to retain solid densities [4]. The high intensity and fast timescales also allow for highresolution imaging of biological systems before the structure is destroyed [5]. On more modest scales, laser-driven systems are being developed to provide EUV radiation for lithography to produce the next generation of integrated circuits, and system designers are turning to simulation to understand and optimize these systems. These situations encompass a large range of temperatures, densities and spatial scales. They each emphasize different aspects of atomic physics and present a variety of challenges for non-LTE modeling. We discuss the relevant issues and summarize the current state of the modeling effort for these applications. [1] M.D. Rosen et al, HEDP 7, 180-190 (2011). [2] B.A. Hammel, et al, Phys. Plasmas 18, 056310 (2011). [3] J.F. Latkowski, et al, Fusion Science and Technology, 60, p. 54-60 (2011). [4] S. Vinko, et al, Nature 482, 59-63 (2012) [5] A. Barty, et al, Nature Photonics 6, 35–40 (2012) This work performed under the auspices of U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

 
Donnerstag, 04.10.2012

joint IAP and DCB seminar on Physical Chemistry

Molecular monolayers on well defined surfaces: structure, bonding and dynamics

Zeit: 11:15 Uhr
Hörsaal: S481 DCB
 
Prof. Dr. Jürg Osterwalder
Physik-Institut
Universität Zürich

 
Donnerstag, 11.10.2012

joint IAP and DCB seminar on Physical Chemistry

NCCR MUST - Methodologies, Strategy, and Goals

Zeit: 11:15 Uhr
Hörsaal: S481 DCB
 
Prof. Dr. Thomas Feurer
Institute of Applied Physics
University of Bern

 
Donnerstag, 18.10.2012

Efimov physics and beyond: Universal few-body phenomena in an ultracold gas of cesium atoms

Zeit: 10:15 Uhr
Hörsaal: B116
 
Dr. Martin Berninger
Institute for Experimental Physics
University of Innsbruck
Austria

Ultracold atomic gases are versatile systems to study fundamental questions of few-body physics due to the full control over their external and internal degrees of freedom. In particular, cesium represents, due to its favourable scattering properties, a prime model system for exploring universal few-body physics.

The main part of this talk covers experimental results connected to the Efimov scenario. This scenario predicts the existence of an infinite series of universally related three-body bound (Efimov) states for resonant two-body interactions. We observed resonance phenomena originating from the coupling of Efimov states to the atomic or atom-dimer continuum. These experimental results agree with the main predictions of universal theory. Recent experimental findings demonstrate that three-body universality persists even when different Feshbach resonances are involved in the tuning of the s-wave scattering length. This result suggests an underlying connection between Efimov and two-body physics.

In a major extension of Efimov physics, a “family” of universally related cluster states tied to an Efimov trimer was predicted. We experimentally observed four- and even five-body cluster states, providing crucial evidence for the existence of such a “family”.

 
Donnerstag, 25.10.2012

Phototriggering Electron Flow in Azurins with a Re(CO)3(diimine)-Tryptophan Unit

Zeit: 09:30 Uhr
Hörsaal: B116
 
Prof. Dr. A. Vlcek, Jr.
School of Biological and Chemical Sciences Queen Mary
University of London, UK

Rhenium(I) tricarbonyl-diimine complexes are strong photooxidants that can trigger electron transfer (ET) in Re-labeled proteins, DNA, or supramolecules. In Re-labeled mutants of the redox protein azurin, photooxidation of the CuI site 20 Å apart is accelerated into the ns time domain provided that a tryptophan (Trp) residuum is placed next to the Re chromophore. Time-resolved IR spectroscopy has identified several ultrafast ET steps and a ~0.5 ns redox equilibrium between electronically excited *ReII(diimine•–) and Trp, producing a charge-separated state ReI(diimine•–)/Trp•+, which then undergoes CuI?Trp•+ ET over ~11 Å in ~30 ns. (TD)DFT calculations reveal strong electronic coupling within the *ReII(diimine•–)/Trp exited state, prior to the ET proper, and suggest that the Re/Trp moiety should be regarded as a single photoactive unit. Importance of direct diimine-Trp(indol) ?-interaction is stressed by comparison with small-molecule models [Re(L-trp)(CO)3(diimine)]+ (L = pyridine, imidazole) with covalently attached but non-stacked Trp that undergo much slower (~30 ns) Trp?*Re ET. As a next step towards developing ultrafast long-range charge separation, we have made a “tryptophan wire” where the Re and Cu azurin sites are separated by 22.4 Å but the CuI?*Re ET occurs in <50 ns by hopping through two intervening tryptophans. Surprisingly, a different mutant with no direct Re-Trp contact was again found to undergo ultrafast Trp?*Re hopping. This puzzle was solved by mass spectrometry and structural studies that revealed that this particular Re-azurin forms dimers with well coupled Re(diimine)-Trp(indole) units at the protein-protein interface, enabling an ultrafast intermolecular ET. This work has interesting implication for designing protein-based photocatalysts (“photoenzymes”).

 
Donnerstag, 01.11.2012

joint IAP and DCB seminar on Physical Chemistry

Ultra-fast thermo mechanical nano-lithography using thermo-dynamically unstable polymers

Zeit: 11:15 Uhr
Hörsaal: S481 DCB
 
Dr. Urs Dürig
IBM Zurich Research Laboratory
Rüschlikon

 
Donnerstag, 08.11.2012

Two-Dimensional Electronic Spectroscopy- Basics and Applications to Bio-Systems

Zeit: 10:15 Uhr
Hörsaal: B116
 
Dr. Jürgen Hauer
Multidimensional Molecular Spectroscopy Group
Photonics Institute
Vienna Technical University

Two-dimensional electronic spectroscopy (2D-ES) with ultrashort pulses is a state-of-the-art tool for the investigation of molecular dynamics, line broadening mechanisms and quantum coherence phenomena in biology. In this talk, I will explain the basics of 2D-ES and compare to other ultrafast experimental techniques like pump-probe. Focusing on biological systems, I will discuss several experimental studies where 2D-ES lead to insightful and experimentally well-founded perspectives on intricate molecular population- and coherence-dynamics. Examples are the exciton dynamics in natural photosynthetic complexes, the energy deactivation network in carotenoids and the relaxation pathways in an artificial light harvesting system. In an outlook, I will demonstrate how 2D-ES is easily upgraded by the use of pulse shaping devices.

 
Donnerstag, 15.11.2012

Multilayer optics for X-ray and Extreme Ultraviolet applications

Zeit: 10:15 Uhr
Hörsaal: B116
 
Dr. Igor A. Artyukov
P.N.Lebedev Physical Institute, Moscow, Russia

This presentation gives a review of recent achievements in the development X-ray/EUV multilayer optics and its applications in compact microscopy and spectrometry. Special attention is paid to the “carbon window” spectral region (4.5 nm < λ < 5 nm), where the carbon and carbon containing materials are extremely transparent. Another example is a table-top soft XUV microscopy at the wavelength 46.9 nm that were carried out in the Colorado State University with a compact capillary discharge laser.

 
Donnerstag, 29.11.2012

Ultrafast coherent photoisomerization in biomimetic photoswitches

Zeit: 10:15 Uhr
Hörsaal: B116
 
Dr. Jérémie Léonard
Institut de Physique et Chimie des Matériaux, IPCMS-DON
Université de Strasbourg - CNRS, France

Within the Department of ultrafast Optics and Nanophotonics (DON) at IPCMS, the BIODYN team (for « BIOmolecular DYNamics ») applies femtosecond spectroscopy to investigate photoinduced ultrafast processes in organic molecules in condensed phase. After introducing shortly our different subjects of interest (organic photovoltaics, biomolecular interactions), I will focus on our latest work on ultrafast coherent photoisomerization in biomimetic photoswitches.

Coherent photoisomerization is a rare, ultrafast process in which the photon energy activates a selected set of reactive vibrational modes, thus ensuring efficient photomechanical energy conversion. We combine experimental and theoretical approaches to investigate this process in a model molecular switch. Transient absorption reveals signatures of a quantum vibrational wave packet that drives the molecular motion from the electronic excited S1 to the ground S0 states, thus mimicking energy conversion in rhodopsin. Quantum chemistry and semi-classical trajectory computations allow us to unravel the mechanistic origin of the observed oscillations.

 
Donnerstag, 06.12.2012

Laser developments for aplications in free electron lasers and high field THz sciences (Promotionsvortrag)

Zeit: 10:15 Uhr
Hörsaal: B116
 
Clemens Ruchert
Laser group of PSI SwissFEL
Paul Scherrer Institut
Villigen

 
Donnerstag, 13.12.2012

joint IAP and DCB seminar on Physical Chemistry

Quantitative, Label-free vibrational microscopy for catalysis

Zeit: 11:15 Uhr
Hörsaal: S481 DCB
 
Prof. Dr. Mischa Bonn
Max-Planck-Institut für Polymerforschung
Mainz, Deutschland

 
Donnerstag, 20.12.2012

Developing your Negotiation Skills in Science - an introduction

Zeit: 10:15 Uhr
Hörsaal: B116
 
Dr. Anna Garry
NCCR MUST Outreach Officer
ETH Zurich - IQE/Ultrafast Laser Physics
Zurich

An interactive workshop to identify the key principles of negotiating, including working on a case study located in a science laboratory. The case study is used to demonstrate how these principles can be applied to find solutions in a scientific work situation.