Inst. Optik und Atomare Physik

149 Items

Recent Submissions
Magnetische und elektronische Eigenschaften von Übergangsmetallkomplexen in der Gasphase

Bülow, Christine (2018)

In dieser Arbeit wurde der Übergang von einem Hochspin- zu einem Niedrigspinzustand in verschiedenen Systemen mit jeweils einem Übergangsmetallatom mittels Röntgenabsorptions- und XMCD-Spektroskopie in der Gasphase untersucht. Im Vordergrund steht die Frage wie dieser magnetische Übergang von der Anzahl der 3d Elektronen, der Struktur und den Liganden abhängt. Dabei wird von in einem früheren P...

Spektroskopie der Neurotransmitter Tryptamin und Phenylethylamin

Schütz, Markus (2018)

The maintenance of bodily functions in living beings is determined by a variety of biochemical processes, collectively referred to as metabolism. Molecular spectroscopy can be used to study processes at the molecular level and to draw conclusions about interactions and possible functionalities. The signal transmission between chemical neurons is based inter alia on the binding of a neurotransmi...

Jitter-correction for IR/UV-XUV pump-probe experiments at the FLASH free-electron laser

Savelyev, Evgeny ; Boll, Rebecca ; Bomme, Cédric ; Schirmel, Nora ; Redlin, Harald ; Erk, Benjamin ; Düsterer, Stefan ; Müller, Erland ; Höppner, Hauke ; Toleikis, Sven ; Müller, Jost ; Kristin Czwalinna, Marie ; Treusch, Rolf ; Kierspel, Thomas ; Mullins, Terence ; Trippel, Sebastian ; Wiese, Joss ; Küpper, Jochen ; Brauβe, Felix ; Krecinic, Faruk ; Rouzée, Arnaud ; Rudawski, Piotr ; Johnsson, Per ; Amini, Kasra ; Lauer, Alexandra ; Burt, Michael ; Brouard, Mark ; Christensen, Lauge ; Thøgersen, Jan ; Stapelfeldt, Henrik ; Berrah, Nora ; Müller, Maria ; Ulmer, Anatoli ; Techert, Simone ; Rudenko, Artem ; Rolles, Daniel (2017)

In pump-probe experiments employing a free-electron laser (FEL) in combination with a synchronized optical femtosecond laser, the arrival-time jitter between the FEL pulse and the optical laser pulse often severely limits the temporal resolution that can be achieved. Here, we present a pump-probe experiment on the UV-induced dissociation of 2,6-difluoroiodobenzene (C6H3F2I) molecules performed ...

Spektroskopie an silizium- und kohlenstoffhaltigen Clustern: Dotierung und Hybride

Savoca, Marco (2018)

Silicon oxides and silicon carbides are not only in the focus of the semiconductor industry and relevant for the development of new materials from clusters and nanoparticles, they are also of interest in the chemistry of the interstellar medium. In this context, the availability of experimental data regarding structure of doped silicon clusters is an essential basis for exploring and controllin...

Off-Axis Electron Holographic Focal Series of GaN

Niermann, Tore (2014)

This is a high resolution off-axis electron hologram series obtained with a transmission electron microscope of a Gallium Nitride (GaN) crystal in <11-20> zoneaxis orientation at atomic resolution. It contains the raw data of two holographic focal series obtained under equal conditions (no strong changes in illumination or microscope setup) a few minutes apart. The first series is a focal serie...

Ultrafast dynamics of nanoparticles in highly intense X-Ray pulses

Bucher, Maximilian Jakob (2017)

With the advent of X-ray free electron laser, such as the Linac Coherent Light Source (LCLS), structural studies on non-repetitive and non-reproducible nanoparticles, such as single bio-molecules appear imminent. A key challenge to increasing the resolution of single particle imaging is radiation damage. Only a sound understanding of the underlying damage processes, such as the nanoplasma expan...

Advanced X-ray analytical methods for the characterization of buried interfaces with relevance for energy conversion devices

Baumann, Jonas (2017)

The efficiency of devices for novel renewable energy sources, like solar cells and thermoelectric generators (TEGs), is strongly increasing since the advent of nanotechnology. Synchrotron radiation-based advanced X-ray fluorescence (XRF) techniques, like grazing emission (GE-) or grazing incidence (GI-) XRF, offer non-destructive and quantitative access to elemental depth profiles in the nanome...

Characterization of nanoparticles by continuous contrast variation in small-angle X-ray scattering

Garcia Diez, Raul (2017)

In the continuously growing field of nanomedicine, nanoparticles have a pre-eminent position. The particle morphology is a defining aspect of their functionality, yet most current characterization techniques possess certain limitations. This work proposes a novel approach to contrast variation in small-angle X-ray scattering based on the constitution of a solvent density gradient in a glass cap...

Stability and properties of methylammonium lead iodide solar cells

Lang, Felix Christian (2017)

Within this thesis, methylammonium lead iodide (CH3NH3PbI3), a hybrid perovskite was studied. Polycrystalline thin-films, processed from solution, reached low defect concentrations of 6.0∙1015 cm-3 and diffusion lengths of 200 nm. Investigating various device structures, a perovskite solar cell with a stabilized efficiency of 12 % was demonstrated. Combining a band gap of 1.6 eV and a low sub-...

Energiedispersive Mikro-Röntgenfluoreszenzanalyse technischer Mikrostrukturen

Bremekamp, Marcel (2017)

Im Rahmen dieser Arbeit wurde ein FP-basiertes Voxelmodell entwickelt, das die Geometrieeffekte in der μ-EDRFA von Mikrostrukturen berücksichtigt und die Quantifizierung der Fluoreszenzintensitäten ermöglicht, die von diesen Mikrostrukturen emittiert werden. Zu diesem Zwecke wurde eine experimentelle Charakterisierung des Spektrometers bezüglich der spektralen Verteilung der Anregungsstrahlung ...

Raman spectroscopic analysis of the calcium oxalate producing extremotolerant lichen Circinaria gyrosa

Böttger, Ute ; Meeßen, Joachim ; Martínez-Frías, Jesús ; Hübers, Heinz-Wilhelm ; Rull, Fernando ; Sánchez, Francisco Javier ; Torre, R. de la ; Vera, Jean Pierre Paul de (2013)

In the context of astrobiological exposure and simulation experiments in the BIOMEX project, the lichen Circinaria gyrosa was investigated by Raman microspectroscopy. Owing to the symbiotic nature of lichens and their remarkable extremotolerance, C. gyrosa represents a valid model organism in recent and current astrobiological research. Biogenic compounds of C. gyrosa were studied that may ser...

Multimethod metrology of multilayer mirrors using EUV and X-Ray radiation

Haase, Anton (2017)

Multilayer mirrors for the extreme ultraviolet (EUV) spectral range are essential optical elements of next-generation lithography systems and in scientific applications, e.g. water window microscopes. Their failure so far to reach theoretically predicted peak reflectivity values significantly hinders their applicability and raises the question of the reasons behind that limited performance. Thi...

Laser-induced fluorescence of free diamondoid molecules

Richter, Robert ; Röhr, Merle I. S. ; Zimmermann, Tobias ; Petersen, Jens ; Heidrich, Christoph ; Rahner, Ramon ; Möller, Thomas ; Dahl, Jeremy E. ; Carlson, Robert M. K. ; Mitric, Roland ; Rander, Torbjörn ; Merli, Andrea (2015)

We observe the fluorescence of pristine diamondoids in the gas phase, excited using narrow band ultraviolet laser light. The emission spectra show well- defined features, which can be attributed to transitions from the excited electronic state into different vibrational modes of the electronic ground state. We assign the normal modes responsible for the vibrational bands, and determine the geom...

XAFS spectroscopy by an X-ray tube based spectrometer using a novel type of HOPG mosaic crystal and optimized image processing

Schlesiger, Christopher ; Anklamm, Lars ; Stiel, Holger ; Malzer, Wolfgang ; Kanngießer, Birgit (2015)

This paper presents recent achievements in laboratory based instrumentation for X-ray Absorption Fine Structure Spectroscopy (XAFS). The key component of the spectrometer is a HAPG mosaic crystal, which is employed in the von Hamos geometry. Due to the high efficiency of HAPG a low power micro focus X-ray tube can serve as an X-ray source. Besides a description of the spectrometer, the paper co...

Colloidal synthesis and optical properties of type-II CdSe-CdTe and inverted CdTe-CdSe core-wing heteronanoplatelets

Antanovich, Artsiom ; Prudnikau, Anatol ; Melnikau, Dimitry ; Rakovich, Yury P. ; Chuvilin, Andrey ; Woggon, Ulrike ; Achtstein, Alexander W. ; Artemyev, Mikhail (2015)

We developed colloidal synthesis to investigate the structural and electronic properties of CdSe-CdTe and inverted CdTe-CdSe heteronanoplatelets and experimentally demonstrate that the overgrowth of cadmium selenide or cadmium telluride core nanoplatelets with counterpartner chalcogenide wings leads to type-II heteronanoplatelets with emission energies defined by the bandgaps of the CdSe and Cd...

Nature of the interaction between rare gas atoms and transition metal doped silicon clusters: the role of shielding effects

Vu Thi Ngan ; Janssens, Ewald ; Claes, Pieterjan ; Fielicke, André ; Minh Tho Nguyen ; Lievens, Peter (2015)

Mass spectrometry experiments show an exceptionally weak bonding between Si7Mn+ and rare gas atoms as compared to other exohedrally transition metal (TM) doped silicon clusters and other SinMn+ (n = 5-10) sizes. The Si7Mn+ cluster does not form Ar complexes and the observed fraction of Xe complexes is low. The interaction of two cluster series, SinMn+ (n = 6-10) and Si7TM+ (TM = Cr, Mn, Cu, and...

Vibrational spectra and structures of SinC clusters (n=3-8)

Nguyen Xuan Truong ; Savoca, Marco ; Harding, Dan J. ; Fielicke, André ; Dopfer, Otto (2015)

The effects of doping bare silicon clusters with carbon on their physical properties are of fundamental interest for the chemistry of the interstellar medium and the development of novel nanostructures in materials science. Carbon-doped silicon clusters (SinC, n = 3-8) are characterized in the gas phase with infrared-ultraviolet two-color ionization (IR-UV2CI) spectroscopy, mass spectrometry, a...

Diastereo-specific conformational properties of neutral, protonated and radical cation forms of (1R,2S)-cis- and (1R,2R)-trans-amino-indanol by gas phase spectroscopy

Bouchet, Aude ; Klyne, Johanna ; Piani, Giovanni ; Dopfer, Otto ; Zehnacker, Anne (2015)

Chirality effects on the intramolecular interactions strongly depend on the charge and protonation states. Here, the influence of chirality on the structure of the neutral, protonated, and radical cation forms of (1R,2S)-cis- and (1R,2R)-trans-1-amino-2-indanol diastereomers, prototypical molecules with two chiral centers, is investigated in a molecular beam by laser spectroscopy coupled with q...

IR spectrum of the protonated neurotransmitter 2-phenylethylamine: dispersion and anharmonicity of the NH3+-pi interaction

Bouchet, Aude ; Schütz, Markus ; Chiavarino, Barbara ; Crestoni, Maria Elisa ; Fornarini, Simonetta ; Dopfer, Otto (2015)

The structure and dynamics of the highly flexible side chain of (protonated) phenylethylamino neurotransmitters are essential for their function. The geometric, vibrational, and energetic properties of the protonated neutrotransmitter 2-phenylethylamine (H(+)PEA) are characterized in the N-H stretch range by infrared photodissociation (IRPD) spectroscopy of cold ions using rare gas tagging (Rg ...

Orbit and spin resolved magnetic properties of size selected [ConRh](+) and [ConAu](+) nanoalloy clusters

Dieleman, Dennis ; Tombers, Matthias ; Peters, Lars ; Meyer, Jennifer ; Peredkov, Sergey ; Jalink, Jeroen ; Neeb, Matthias ; Eberhardt, Wolfgang ; Rasing, Theo ; Niedner-Schatteburg, Gereon ; Kirilyuk, Andrei (2015)

Bi-metallic nanoalloys of mixed 3d-4d or 3d-5d elements are promising candidates for technological applications. The large magnetic moment of the 3d materials in combination with a high spin-orbit coupling of the 4d or 5d materials give rise to a material with a large magnetic moment and a strong magnetic anisotropy, making them ideally suitable in for example magnetic storage devices. Especial...