16-20 September 2013
Magnus-Haus of the German Physical Society
Europe/Berlin timezone
Home > Contribution List
Displaying 47 contributions out of 47
Type: contributed talk Session: X-Ray interactive with matter 1
The oxygen K-edge x-ray emission (XE) spectrum of liquid water at ultra-high x-ray fluences was studied at the SXR Instrument of the x-ray free electron laser (FEL) LCLS. XE spectra were measured from a liquid micro-jet in vacuum for a wide range of x-ray fluences by varying x-ray spot size, flux and pulse duration. The threshold fluence for reproducing reference data measured at BESSY II could ... More
Presented by Mr. Simon SCHRECK
Type: contributed talk Session: X-Ray interactive with matter 1
Using ultrashort X-ray pulses from the Linac Coherent Light Source we carried out a pump-probe resonant inelastic x-ray scattering (RIXS) experiment on Fe(CO)5 photodissociation in ethanol. This allowed us to follow the evolution of the valence electronic structure of the iron carbonyl species in an element- and chemical-selective way with a 300 fs (FWHM) time resolution. Supported by novel ab ini ... More
Presented by Mr. Kristjan KUNNUS
Type: poster contribution
Coordination compounds are appealing targets for the development of light-harvesting devices. Currently Ru(II)-complexes are widely used but Cu(I)-compounds, in particular Cu(I)-phenanthrolines, are considered as promising alternative. In comparison Cu is more cost effective and environmentally friendly [1]. The metal-to-ligand-charge-transfer (MLCT) excited state of these Cu(I)-phenanthroline com ... More
Presented by Dr. Katharina KUBICEK
Type: contributed talk Session: Quantum materials 2
BiFeO3 had a deep impact in the field of multiferroics, since it is magnetic and ferroelectric at room temperature, opening a wide field of applications, e.g. for spintronics and memory devices which can be addressed both magnetically and electrically. Furthermore, it is highly desirable to photo-control the polarization and magnetization in BiFeO3 directly by ultrafast optical excitation. Here w ... More
Presented by Mr. Daniel SCHICK
Type: poster contribution
We investigate coherent phonon propagation in a thin film of ferroelectric Pb(Zr0.2Ti0.8)O3 (PZT) by ultrafast X-ray diffraction (UXRD) experiments, which are analyzed as time-resolved reciprocal space mapping (RSM) in order to observe the in- and out-of-plane structural dynamics simultaneously.[1] The mosaic structure of the PZT leads to a coupling of the excited out-of-plane expansion to in-plan ... More
Presented by Mr. Daniel SCHICK
Type: contributed talk Session: Quantum materials
Antiferromagnetic (AFM) materials have been predicted to show ultrafast magnetic dynamics since no macroscopic magnetization exists and dynamics might not be restricted by conservation of angular momentum. Out of recent studies investigating ferromagnetic materials like pure 4f elements (Gd,Tb,..) or a combination of 3d and 4f elements with (GdFeCo,..) it turned out that that the fast demagnetizat ... More
Presented by Mr. Christoph TRABANT
Type: contributed talk Session: Quantum materials 2
Controlling magnetic states of matter on ultrashort timescales is crucial to engineering the next-generation magnetic devices combining ultrafast data processing with ultrahigh-density data storage. Here, we report on femtosecond laser-driven dynamics of multi-sublattice magnetic materials, with both ferromagnetic and antiferromagnetic coupling between sublattices, investigated using element-sp ... More
Presented by Dr. Ilie RADU
Type: poster contribution
We present two-photon photoemission measurements on the p-doped topological insulator Sb2Te2S. The Dirac cone of this system lies above the Fermi energy and is therefore only accessible using two-photon photoemission. We detect the photoemitted electrons with an angle-resolving time-of-flight spectrometer. This instrument allows us to measure the kinetic energy E as a function of both k di ... More
Presented by Thomas KUNZE
Type: contributed talk Session: Quantum materials 2
We designed and performed a time- and angle- resolved photoemission experiment to investigate the electronic structure of a ferromagnetic Gadolinium film during ultrafast laser-induced demagnetization and subsequent thermal recovery. To get a complete picture of the magnetization dynamics we track the binding energy of the exchange-split valence band, which mediates the exchange interaction betw ... More
Presented by Björn FRIETSCH
Type: poster contribution
SrTiO3 (STO) is a dielectric perovskite that shows quantum paraelectric behavior at low temperatures. It is widely used as a substrate for the growth of perovskite layers and has been intensively studied for its various structural phase transitions. The elastic behaviour of STO has been studied since the 60ies and has recently attracted attention due to the high mobility of domain walls in the an ... More
Presented by Lena MAERTEN
Type: contributed talk Session: Quantum materials
The determination of the absorption coefficient via transmission experiments is not always feasible. Common alternative methods for X-ray absorption spectroscopy (XAS) are the detection of electron and fluorescence yield (FY), implying that these are proportional to the absorption coefficient. This assumption is generally justified for the electron yield. The FY is influenced by saturation effects ... More
Presented by Ms. Nele THIELEMANN-KüHN
Type: poster contribution
We use inelastic scattering of ultrashort visible and hard X-ray pulses as a probe of the transient occupation of phonon modes constituting large amplitude strain-wavepackets. These Brillouin scattering experiments permit the time-resolved observation of the phonon dynamics including the phonon damping and nonlinear interaction. We use a variety of excitation schemes to synthesize high amplitude p ... More
Presented by Mr. André BOJAHR
Type: poster contribution
We present recent results from ultrafast laser-driven magnetization dynamics experiments on the rare-earth local-moment ferromagnets Gadolinium and Terbium. Our experiment combines angle-resolved photoemission spectroscopy (ARPES) with the VUV photon energies and time resolution made possible by high-order harmonic generation to scrutinize the non-equilibrium band structure followi ... More
Presented by Dr. Robert CARLEY
Type: contributed talk Session: Quantum materials 2
Over the past decade, femtosecond optical laser pulses have fueled the discovery of ultrafast spin dynamics in magnetic materials that go beyond our equilibrium understanding of magnetism. Many of these phenomena are potentially suitable for future technological applications. For example, fs optical laser pulses can act as a stimulus to reverse the magnetization direction in ferrimagnetic GdFeCo, ... More
Presented by Ms. Catherine GRAVES
Type: poster contribution
Charge and energy transfer processes at organic-metal interfaces are of key relevance in molecular electronics and functionalization of surfaces with molecular switches. Therefore the electronic structure and femtosecond electron dynamics of self-assembled monolayers (SAMs) of azobenzene-functionalized alkanethiols on gold have been investigated with time-resolved two-photon photoemission spectros ... More
Presented by Dr. Cornelius GAHL, Mr. Thomas MOLDT
Type: contributed talk Session: Quantum materials 2
Magnetite (Fe3O4), is the first oxide where a relationship between electrical conductivity and fluctuating/localized charges was observed, with a drop in conductivity by two orders of magnitude at T=123K. The Verwey transition is accompanied by a structural change from monoclinic to cubic symmetry. Despite decades of research and indications that charge and orbital ordering play an important role ... More
Presented by Ms. Roopali KUKREJA
Type: poster contribution
Following the pioneering femtosecond spectroscopy experiments by A. Zewail and coworkers, the coherent electronic and nuclear wavepacket dynamics in photo-excited NaI molecules are revisited by means of sub-100 fs resolution pump-probe photoelectron spectroscopy. Time, energy and angular resolved photoelectron distributions of NaI photo-excited with several pump wavelengths were been measured. The ... More
Presented by Torsten LEITNER
Type: poster contribution
Correlated materials such as transition-metal oxides exhibit nanoscale structures resulting from e.g. magnetic, orbital or charge order. While resonant scattering of soft x-rays in transmission geometry provides unique sensitivity to such ordering and can also enable high resolution imaging, most samples have to be grown epitaxially on single crystalline substrates and are not penetrable by soft x ... More
Presented by Stefanie FRöMMEL
Type: poster contribution
Magnetic bubbles are skyrmionic spin structures stabilized by dipolar interactions. Recent theoretical investigations predict a GHz gyrotropic motion of these topological configurations after excitation in a restoring potential, analogous to vortex gyration. However, in contrast to vortices, bubbles are predicted to exhibit inertial effects. Here we demonstrate the presence of an inertial mass in ... More
Presented by Michael SCHNEIDER
Type: invited talks Session: X-ray interaction with matter 2
My talk will give a historic perspective of the revolutionary science that was enabled by the advent of high power sources of coherent electromagnetic radiation and the implications for future scientific opportunities with x-ray free electron lasers (X-FELs). The historical journey starts with the development of radar microwave sources in the 1940s that fueled the development of nuclear magnetic r ... More
Presented by Prof. Joachim STOHR
Type: poster contribution
In the last decade hard x-ray high kinetic energy photoelectron spectroscopy (HAXPES or HIKE) has led to a break-through in the field of photoemission due to its non destructive way of investigating the bulk electronic properties of materials and in particular buried interfaces in layered systems. Nanolayered systems are the keystones of current and future devices. The electronic, magnetic and mag ... More
Presented by Dr. Mihaela GORGOI
Type: contributed talk Session: Quantum materials
Author: B. Shi: Van der Waals-Zeeman Institute, University of Amsterdam, the Netherlands Co-authors: J. B. Goedkoop, M. S. Golden: Van der Waals-Zeeman Institute, University of Amsterdam, the Netherlands C. Schüssler-Langeheine : Helmholtz-Zentrum Berlin, Germany M. Buchholz, C. Trabant, C. F. Chang: II. Physikalisches Institut, Universität zu Köln, Germany A. Ricci, C. Gutt, M. Spr ... More
Presented by Mr. Bo SHI
Type: poster contribution
Experimentally determined adsorption geometries of molecular switches are essential both for understanding their functionalities and for benchmarking ab initio calculations. The prototypical molecular switch azobenzene is investigated on the Ag(111) surface by means of the normal incidence x-ray standing wave (NIXSW) technique and dispersion-corrected density functional theory (DFT) calculations. ... More
Presented by Dr. Giuseppe MERCURIO
Type: poster contribution
The current status of project P2 “Ultrafast charge transfer and isomerization dynamics of molecules” will be presented. The goal is to resolve the early-stage dynamics of energy relaxation concomitant with structural rearrangements in Fe(CO)5 in the gas phase. Photoexcitation generates a metal-to-ligand charge transfer in Fe(CO)5 that launches a sequence of processes on time scales of 20-30 fs ... More
Presented by Mr. Henning SCHRöDER
Type: poster contribution
Lattice vibrations after femtosecond laser excitation can be launched by different processes such as the relaxation of hot electrons or the coupling of the laser pulses to the lattice via nonlinear-optical mechanisms. The pathway and time scale of energy transfer form photonic excitation to the phononic subsystem is of fundamental interest to understand various physical phenomena like e.g. laser-d ... More
Presented by Ms. Carla STREUBüHR
Type: poster contribution
The low-energy excitations of magnetic solids, as for instance magnons and phonons, are ultimately responsible for dynamic magnetization phenomena like demagnetization and magnetization switching, and therefore of paramount importance for a microscopic understanding of these processes. Here, we report on a systematic study of the spectral fingerprints of these quasiparticles on ferrimagnetic Ho3F ... More
Presented by Mr. Sergej SOLOPOW
Type: poster contribution
Time resolved photoemission from core levels (trPES) at FELs is a tool for studying surface dynamics in real-time. Basis for this is the sensitivity of core-levels to their chemical environment. By probing their spectral evolution after an ultra-short excitation one can get insight on both, electronically caused excitations (fs- up to several-ps time-scales) as well as responses of the crystal lat ... More
Presented by Florian HIEKE
Type: poster contribution
Motivated by the x-ray induced ultra-fast transient drop of optical reflectivity of semi-conductors, we performed time-resolved photoemission (trPES) experiments with x-ray pump x-ray probe in order to understand the x-ray induced changes in the electronic structure of GaAs(100). To accomplish our measurements we were using the split-and-delay unit at PG2 beamline at the free-electron laser facili ... More
Presented by Mr. Lukas WENTHAUS
Type: contributed talk Session: Molecular dynamics 2
Since demonstration of high-order harmonic generation (HHG) by femtosecond laser pulses, time-resolved XUV spectroscopy has become an attractive tool to study molecular dynamics via detection of charged particles (electrons and ions). Information collected in these experiments is typically complicated due to broad spectral content of the HHG sources. In this contribution we present implementation ... More
Presented by Dr. Oleg KORNILOV
Type: poster contribution
State-selected aligned and oriented molecular ensembles serve as ideal samples to study ultrafast molecular dynamics in the molecular frame. Possible probing mechanisms are the investigation of molecular-frame photoelectron angular distributions or the detection of structural changes via X-ray and electron diffraction. We have developed techniques to manipulate the motion of molecules in cold s ... More
Presented by Dr. Terence G. MULLINS, Prof. Jochen KüPPER
Type: poster contribution
Complex molecules often exhibit different structural isomers (conformers). In order to study the structure and dynamics of a molecule it is highly desirable to have a pure sample of the individual conformers. In this contribution we present a technique to spatially separate the conformers of complex, neutral molecules as well as individual cluster sizes of molecules using a Stark deflector. The mo ... More
Presented by Dr. Terence G. MULLINS, Prof. Jochen KüPPER
Type: invited talks Session: Molecular dynamics 2
We are developing methods to manipulate the translational and rotational motion of large molecules for the investigation of their molecular dynamics and chemical reactivities. This includes the deflection [1,2], focusing [3], and deceleration [4] of these molecules with electric fields, as well as the control of their rotational motion using electric brute-force orientation, laser alignment and mi ... More
Presented by Prof. Jochen KüPPER
Type: invited talks Session: Molecular dynamics 2
We employ quantum chemical calculations and molecular dynamics simulations in the study of ultra-fast solution dynamics. The theoretical tools are crucial for the interpretation of X-ray and photo-electron spectra of aqueous solutions. Simulations of photo-induced chemical processes require a computational framework, in which we can calculate spectra in excited states and of molecules undergoin ... More
Presented by Dr. Michael ODELIUS
Type: invited talks Session: Molecular dynamics 2
Different conformations (rotational isomers) of a molecule can exhibit different reactivities, due to differences in chemical shape and electronic properties. This provides a perspective to manipulate chemical reactions by selecting molecular conformations. To explore this dependence, we study gas-phase bimolecular reactive collisions between conformer-selected neutral molecules of 3-aminophenol [ ... More
Presented by Prof. Jochen KüPPER
Type: contributed talk Session: Molecular dynamics 2
Nowadays some of the most interesting processes investigated by the of X-ray fluorescence unfortunately have very low efficiencies by themselves. So the demand for very efficient beamlines with a high transmission of photons arose. As sometimes the conventional design of X-ray optical setups does not provide sufficient flux, leading to very bad statistics in evaluation of the obtained data, differ ... More
Presented by Mr. Jens REHANEK
Type: invited talks Session: Molecular dynamics 1
X-ray free-electron lasers (XFELs) provide extremely intense femtosecond x-ray pulses that promise access to high-resolution structure determination, while outrunning any radiation damage. To achieve this goal, however, requires the ability to describe the dynamical behavior of heavy atoms in high-intensity x-ray pulses. In early 2012, a new XFEL facility, the SPring-8 Angstrom Compact free electr ... More
Presented by Prof. Kiyoshi UEDA
Type: contributed talk Session: X-ray interaction with matter 2
The oxygen K-edge x-ray emission (XE) spectrum of liquid water at ultra-high x-ray fluences was studied at the SXR Instrument of the x-ray free electron laser (FEL) LCLS. XE spectra were measured from a liquid micro-jet in vacuum for a wide range of x-ray fluences by varying x-ray spot size, flux and pulse duration. The threshold fluence for reproducing reference data measured at BESSY II could ... More
Presented by Mr. Simon SCHRECK
Type: invited talks Session: Molecular dynamics 2
The solvent plays a crucial role in the intramolecular relaxation and structural dynamics of transition metal complexes. However, quantifying its effect is not trivial due to the lack of clear observables. Using a range of novel ultrafast tools, in particular multidimensional UV spectroscopy and X-ray absorption spectroscopy (XAS), we will present a study of photooxidation and photoaquation of tra ... More
Presented by Prof. Majed CHERGUI
Type: invited talks Session: Quantum materials 2
Magnetically ordered materials are the macroscopic manifestation of one of the strongest quantum effects - spin-spin exchange interaction - the strength of which can reach 1000 Tesla. Excitation of magnetic materials with femtosecond laser pulses has been shown to lead to ultrafast (< 1 ps) demagnetization, phase transitions and even reversal of the magnetization, creating a new field of ultrafast ... More
Presented by Dr. Alexey KIMEL
Type: poster contribution
Femtosecond visible laser pulses can be used to drive surface reactions either directly by hot carriers or indirectly by the heat generated through phonon coupling of hot charged particles. We studied the dynamics of one such prototypical catalytic reaction, the femtosecond laser-induced CO oxidation reaction on a Ru(0001) surface, using the Linac Coherent Light Source (LCLS) free electron x-ray l ... More
Presented by Dr. Jerry LARUE
Type: poster contribution Session: Hot topics and posters
The Materials Imaging and Dynamics (MID) station at the forthcoming European X-ray Free-Electron Laser facility (XFEL.EU) will allow investigations of materials using wide- and small-angle X-ray scattering techniques. The special features of the radiation from XFEL.EU allow novel experiments to be conducted, for instance exploiting the temporal structure and coherence properties of the X-rays. Of ... More
Presented by Dr. Jörg HALLMANN
Type: poster contribution
The protein cytochrome c plays an active role in biological processes in humans and animals. The knowledge of the electronic structure of this protein including bonding and reaction properties related to the valence state of its central iron ion is crucial, but difficult to address directly. In this study, the hard X-ray based method of resonant inelastic X-ray scattering (1s2p RIXS) will be intro ... More
Presented by Dr. Thomas KROLL
Type: contributed talk Session: X-ray interaction with matter 2
The use of elastic x-ray scattering for studying electronic and magnetic structures of matter is based on the premise that the scattered x-rays provide information on an as-prepared state. The new free-electron-laser (FEL) sources of ultraintense and ultrashort pulses of extreme x-ray radiation challenge this premise. Here, the results of a resonant magnetic scattering experiment at the FEL source ... More
Presented by Mr. Bastian PFAU
Type: contributed talk Session: Molecular dynamics 2
The protonated water dimer irradiated with the free-electron laser FLASH at DESY (90 eV) undergoes Coulomb-explosion after losing one of its valence electrons via photoionization [1]. Because of the close-lying outer valence orbitals and various conical intersections, non-adiabatic effects are presumably important for the overall dynamics. Ab initio potential energy surfaces for the three lowest d ... More
Presented by Mr. Zheng LI, Dr. Oriol VENDRELL
Type: contributed talk Session: Molecular dynamics 2
Liquid water is the single most important medium in which chemical and biological processes take place. Rather than acting as passive environment, the dynamics of water during chemical and biological processes play a fundamental role in the solvation and stabilization of reaction intermediate. The possibility to generate sub-ps and very intense THz pulses at free-electron lasers in full synchroniz ... More
Presented by Mr. Pankaj Kumar MISHRA
Type: contributed talk Session: Quantum materials 2
In ultrafast demagnetization of ferromagnetic metals after femtosecond laser excitation, a central question is how spin angular momentum can be transferred under the optically excited nonequilibrium conditions. One would expect this to happen on the timescale of spin-lattice relaxation, which has however been found to be on the order of 100 ps for Gd [1], much slower than ultrafast demagnetization ... More
Presented by Dr. Andrea ESCHENLOHR
Type: poster contribution
Understanding ultrafast all-optical magnetization switching (AOS), i.e. the permanent reversal of the magnetization by the sole action of a femtosecond laser pulse in the absence of any applied magnetic field, is a challenging issue which could have tremendous impact for the magnetic recording industry. While a qualitative agreement between spin atomistic simulations and experiments exists[1], the ... More
Presented by Dr. Loïc LE GUYADER