Inst. Optik und Atomare Physik

237 Items

Recent Submissions
Probing ultrafast electron dynamics in helium nanodroplets with deep learning assisted diffraction imaging

Zimmermann, Julian Claudius (2021)

Coherent diffraction imaging (CDI) of single particles in free flight enables studying the structural composition of fragile nano-scaled matter. Such experiments demand high-intensity extreme ultra- violet (XUV) or X-ray light pulses, until recently only achievable at large-scale free-electron laser facilities. In this thesis, data from the first time-resolved infrared (IR), XUV pump-probe sing...

Simulation of the θ′ Precipitation Process with Interfacial Anisotropy Effects in Al-Cu Alloys

Ta, Na ; Bilal, Muhammad Umer ; Häusler, Ines ; Saxena, Alaukik ; Lin, Yueh-Yu ; Schleifer, Felix ; Fleck, Michael ; Glatzel, Uwe ; Skrotzki, Birgit ; Darvishi Kamachali, Reza (2021-03-08)

The effects of anisotropic interfacial properties and heterogeneous elasticity on the growth and ripening of plate-like θ′-phase (Al2Cu) in Al-1.69 at.% Cu alloy are studied. Multi-phase-field simulations are conducted and discussed in comparison with aging experiments. The precipitate/matrix interface is considered to be anisotropic in terms of its energy and mobility. We find that the additio...

Microhydration of PAH+ cations: evolution of hydration network in naphthalene+-(H2O)n clusters (n ≤ 5)

Chatterjee, Kuntal ; Dopfer, Otto (2018-01-24)

The interaction of polycyclic aromatic hydrocarbon molecules with water (H2O = W) is of fundamental importance in chemistry and biology. Herein, size-selected microhydrated naphthalene cation nanoclusters, Np+-Wn (n ≤ 5), are characterized by infrared photodissociation (IRPD) spectroscopy in the C–H and O–H stretch range to follow the stepwise evolution of the hydration network around this prot...

Grazing Emission X‐Ray Fluorescence: Novel Concepts and Applications for Nano‐Analytics

Baumann, Jonas ; Kayser, Yves ; Kanngießer, Birgit (2020-11-03)

Angle‐resolved X‐ray fluorescence spectroscopy gives access to elemental analysis of nanoscaled materials. The two main techniques of this method are grazing incidence X‐ray fluorescence (GIXRF) and grazing emission X‐ray fluorescence (GEXRF) spectroscopy. Principles of both techniques including main applications are discussed in this Review. The main focus lies on the description of GEXRF tech...

Untersuchung und Anwendung der dynamischen Beugung an inhomogenen Verschiebungsfeldern in Elektronenstrahlrichtung in Halbleiterheterostrukturen

Niermann, Laura (2021)

In dieser Arbeit wird der Einfluss des dynamischen Beugungsverhalten bei inhomogenen Verschiebungsfeldern in Elektronenstrahlrichtung auf die gebeugte Elektronenwelle experimentell und theoretisch untersucht. Die Dunkelfeldphase der gebeugten Elektronenwelle ist sensitiv auf das Verschiebungsfeld. Unter dynamischen Beugungsbedingungen ist dabei kein linearer Zusammenhang zwischen der Dunkelfeld...

Quantitative PA tomography of high resolution 3-D images: Experimental validation in a tissue phantom

Buchmann, Jens ; Kaplan, Bernhard ; Powell, Samuel ; Prohaska, Steffen ; Laufer, Jan (2020-01-08)

Quantitative photoacoustic tomography aims to recover the spatial distribution of absolute chromophore concentrations and their ratios from deep tissue, high-resolution images. In this study, a model-based inversion scheme based on a Monte-Carlo light transport model is experimentally validated on 3-D multispectral images of a tissue phantom acquired using an all-optical scanner with a planar d...

Three-dimensional quantitative photoacoustic tomography using an adjoint radiance Monte Carlo model and gradient descent

Buchmann, Jens ; Kaplan, Bernhard A. ; Powell, Samuel ; Prohaska, Steffen ; Laufer, Jan (2019-06-06)

Quantitative photoacoustic tomography aims to recover maps of the local concentrations of tissue chromophores from multispectral images. While model-based inversion schemes are promising approaches, major challenges to their practical implementation include the unknown fluence distribution and the scale of the inverse problem. We describe an inversion scheme based on a radiance Monte Carlo mode...

Erzeugung und spektroskopische Untersuchung von Edelmetall-Adamantanthiol Hybridclustern

Bischoff, Tobias (2021)

In der vorliegenden Dissertation wurden erstmalig Hybridcluster aus kleinen Edelmetallclustern und dem Diamantoid 1-Adamantanthiol (HSAdm) erzeugt und spektroskopisch untersucht. In der Literatur finden sich viele Beispiele für verstärkende Einflüsse größerer Metallnanopartikel auf die optischen Eigenschaften von Molekülen in deren Umgebung. Bisher sind jedoch kaum experimentelle Untersuchungen...

Volt‐per‐Ångstrom terahertz fields from X‐ray free‐electron lasers

Tanikawa, T. ; Karabekyan, S. ; Kovalev, S. ; Casalbuoni, S. ; Asgekar, V. ; Bonetti, S. ; Wall, S. ; Laarmann, T. ; Turchinovich, D. ; Zalden, P. ; Kampfrath, T. ; Fisher, A. S. ; Stojanovic, N. ; Gensch, M. ; Geloni, G. (2020-04-29)

The electron linear accelerators driving modern X‐ray free‐electron lasers can emit intense, tunable, quasi‐monochromatic terahertz (THz) transients with peak electric fields of V Å−1 and peak magnetic fields in excess of 10 T when a purpose‐built, compact, superconducting THz undulator is implemented. New research avenues such as X‐ray movies of THz‐driven mode‐selective chemistry come into re...

Terahertz Nonlinear Optics of Graphene: From Saturable Absorption to High‐Harmonics Generation

Hafez, Hassan A. ; Kovalev, Sergey ; Tielrooij, Klaas‐Jan ; Bonn, Mischa ; Gensch, Michael ; Turchinovich, Dmitry (2019-11-04)

Graphene has long been predicted to show exceptional nonlinear optical properties, especially in the technologically important terahertz (THz) frequency range. Recent experiments have shown that this atomically thin material indeed exhibits possibly the largest nonlinear coefficients of any material known to date, paving the way for practical graphene‐based applications in ultrafast (opto‐)elec...

Microhydration of substituted diamondoid radical cations of biological relevance: infrared spectra of amantadine+-(H2O)n = 1–3 clusters

George, Martin Andreas Robert ; Buttenberg, Friedrich ; Förstel, Marko ; Dopfer, Otto (2020-11-18)

Hydration of biomolecules and pharmaceutical compounds has a strong impact on their structure, reactivity, and function. Herein, we explore the microhydration structure around the radical cation of the widespread pharmaceutical drug amantadine (C16H15NH2, Ama) by infrared photodissociation (IRPD) spectroscopy of mass-selected Ama+Wn = 1–3 clusters (W = H2O) recorded in the NH, CH, and OH stretc...

Synergy Effect of Combined Near and Mid-Infrared Fibre Spectroscopy for Diagnostics of Abdominal Cancer

Hocotz, Thaddäus ; Bibikova, Olga ; Belikova, Valeria ; Bogomolov, Andrey ; Usenov, Iskander ; Pieszczek, Lukasz ; Sakharova, Tatiana ; Minet, Olaf ; Feliksberger, Elena ; Artyushenko, Viacheslav ; Rau, Beate ; Zabarylo, Urszula (2020-11-23)

Cancers of the abdominal cavity comprise one of the most prevalent forms of cancers, with the highest contribution from colon and rectal cancers (12% of the human population), followed by stomach cancers (4%). Surgery, as the preferred choice of treatment, includes the selection of adequate resection margins to avoid local recurrences due to minimal residual disease. The presence of functionall...

Tuning exciton diffusion, mobility and emission line width in CdSe nanoplatelets via lateral size

Achtstein, Alexander W. ; Ayari, Sabrine ; Helmrich, Sophia ; Quick, Michael T. ; Owschimikow, Nina ; Jaziri, Sihem ; Woggon, Ulrike (2020-11-02)

We investigate the lateral size tunability of the exciton diffusion coefficient and mobility in colloidal quantum wells by means of line width analysis and theoretical modeling. We show that the exciton diffusion coefficient and mobility in laterally finite 2D systems like CdSe nanoplatelets can be tuned via the lateral size and aspect ratio. The coupling to acoustic and optical phonons can be ...

Zeitaufgelöste Dynamik von Clustern in intensiven extrem ultravioletten Doppelpulsen

Sauppe, Mario (2020)

With their brilliant short-wavelength light pulses, free-electron lasers (FEL) enable an unique insight into the interaction of light and matter. By recording scattering patterns, coherent diffractive imaging allows to image and investigate single nanometer-sized particles. If such an intense light pulse intersects with a nanoparticle, it will be ionized multiple times and a sequence of mainly ...

Coherent soft X-ray diffraction imaging of coliphage PR772 at the Linac coherent light source

Reddy, Hemanth K.N. ; Yoon, Chun Hong ; Aquila, Andrew ; Awel, Salah ; Ayyer, Kartik ; Barty, Anton ; Berntsen, Peter ; Bielecki, Johan ; Bobkov, Sergey ; Bucher, Maximilian ; Carini, Gabriella A. ; Carron, Sebastian ; Chapman, Henry ; Daurer, Benedikt ; DeMirci, Hasan ; Ekeberg, Tomas ; Fromme, Petra ; Hajdu, Janos ; Hanke, Max Felix ; Hart, Philip ; Hogue, Brenda G. ; Hosseinizadeh, Ahmad ; Kim, Yoonhee ; Kirian, Richard A. ; Kurta, Ruslan P. ; Larsson, Daniel S.D. ; Duane Loh, N. ; Maia, Filipe R.N.C. ; Mancuso, Adrian P. ; Mühlig, Kerstin ; Munke, Anna ; Nam, Daewoong ; Nettelblad, Carl ; Ourmazd, Abbas ; Rose, Max ; Schwander, Peter ; Seibert, Marvin ; Sellberg, Jonas A. ; Song, Changyong ; Spence, John C.H. ; Svenda, Martin ; Van der Schot, Gijs ; Vartanyants, Ivan A. ; Williams, Garth J. ; Xavier, P. Lourdu (2017-06-27)

Single-particle diffraction from X-ray Free Electron Lasers offers the potential for molecular structure determination without the need for crystallization. In an effort to further develop the technique, we present a dataset of coherent soft X-ray diffraction images of Coliphage PR772 virus, collected at the Atomic Molecular Optics (AMO) beamline with pnCCD detectors in the LAMP instrument at t...

A tabletop setup for ultrafast helicity-dependent and element-specific absorption spectroscopy and scattering in the extreme ultraviolet spectral range

Yao, Kelvin ; Willems, Felix ; Korff Schmising, Clemens von ; Strüber, Christian ; Hessing, Piet ; Pfau, Bastian ; Schick, Daniel ; Engel, Dieter ; Gerlinger, Kathinka ; Schneider, Michael ; Eisebitt, Stefan (2020-09-23)

Further advances in the field of ultrafast magnetization dynamics require experimental tools to measure the spin and electron dynamics with element-specificity and femtosecond temporal resolution. We present a new laboratory setup for two complementary experiments with light in the extreme ultraviolet (XUV) spectral range. One experiment is designed for polarization-dependent transient spectros...

Element-Specific Magnetization Dynamics of Complex Magnetic Systems Probed by Ultrafast Magneto-Optical Spectroscopy

von Korff Schmising, Clemens ; Willems, Felix ; Sharma, Sangeeta ; Yao, Kelvin ; Borchert, Martin ; Hennecke, Martin ; Schick, Daniel ; Radu, Ilie ; Strüber, Christian ; Engel, Dieter W. ; Shokeen, Vishal ; Buck, Jens ; Bagschik, Kai ; Viefhaus, Jens ; Hartmann, Gregor ; Manschwetus, Bastian ; Grunewald, Soeren ; Düsterer, Stefan ; Jal, Emmanuelle ; Vodungbo, Boris ; Lüning, Jan ; Eisebitt, Stefan (2020-10-28)

The vision to manipulate and control magnetism with light is driven on the one hand by fundamental questions of direct and indirect photon-spin interactions, and on the other hand by the necessity to cope with ever growing data volumes, requiring radically new approaches on how to write, read and process information. Here, we present two complementary experimental geometries to access the eleme...

Stimulated Raman Scattering in Melilite‐Type Crystals Ca2MgSi2O7 and Ca2Ga2SiO7

Kaminskii, Alexander A. ; Bohatý, Ladislav ; Eichler, Hans Joachim ; Lux, Oliver ; Rhee, Hanjo ; Burianek, Manfred ; Becker, Petra (2020-06-14)

χ(3)‐nonlinear optical interactions in two melilite‐type stimulated Raman scattering (SRS)‐active non‐centrosymmetric crystals, Ca2MgSi2O7 and Ca2Ga2SiO7, formerly known as Nd3+‐laser media, are presented. Under picosecond pumping at 1.064 and 0.532 µm cascaded and cross‐cascaded effects occur in these tetragonal silicates. Besides the SRS‐promoting phonon modes with energy of ωSRS1 ≈ 908 cm−1 ...

Microscopic investigations of inhomogeneities and metastable effects in Cu(In,Ga)Se2 solar cells

Nikolaeva, Aleksandra (2020-09-15)

Although Cu(In,Ga)Se2 (CIGS) thin- film solar cells exhibit power conversion effciencies of more than 23%, there are still open questions concerning factors limiting the photovoltaic performance of the record devices. Band-gap and electrostatic potential fuctuations can be considered as possible reasons of deteriorated photovoltaic performance of CIGS solar cells via enhanced recombination. In ...

Ultrafast demagnetization dominates fluence dependence of magnetic scattering at Co M edges

Schneider, Michael ; Pfau, Bastian ; Günther, Christian M. ; Korff Schmising, Clemens von ; Weder, David ; Geilhufe, Jan ; Perron, Jonathan ; Capotondi, Flavio ; Pedersoli, Emanuele ; Manfredda, Michele ; Hennecke, Martin ; Vodungbo, Boris ; Lüning, Jan ; Eisebitt, Stefan (2020-09-15)

We systematically study the fluence dependence of the resonant scattering cross-section from magnetic domains in Co/Pd-based multilayers. Samples are probed with single extreme ultraviolet (XUV) pulses of femtosecond duration tuned to the Co M3,2 absorption resonances using the FERMI@Elettra free-electron laser. We report quantitative data over 3 orders of magnitude in fluence, covering 16  mJ/...