Institut für Optik und Atomare Physik

144 Items

Recent Submissions
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 ; de la Torre, R. ; de Vera, Jean Pierre Paul (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...

Single water solvation dynamics in the 4-aminobenzonitrile-water cluster cation revealed by picosecond time-resolved infrared spectroscopy

Miyazaki, Mitsuhiko ; Nakamura, Takashi ; Wohlgemuth, Matthias ; Mitrić, Roland ; Dopfer, Otto ; Fujii, Masaaki (2015)

The dynamics of a solvent is important for many chemical and biological processes. Here, the migration dynamics of a single water molecule is triggered by the photoionization of the 4-aminobenzonitrile-water (4ABN-W) cluster and monitored in real time by picosecond time-resolved IR (ps TRIR) spectroscopy. In the neutral cluster, water is hydrogen-bonded to the CN group. When this CN-bound clust...

Mass analyzed threshold ionization detected infrared spectroscopy: isomerization activity of the phenol-Ar cluster near the ionization threshold

Miyazaki, Mitsuhiko ; Yoshikawa, Shunpei ; Michels, François ; Misawa, Kentaro ; Ishiuchi, Shun-ichi ; Sakai, Makoto ; Dopfer, Otto ; Müller-Dethlefs, Klaus ; Fujii, Masaaki (2015)

The structure of the phenol-argon cluster (PhOH-Ar) in high-n Rydberg states is investigated by the newly developed technique of mass analyzed threshold ionization detected infrared (MATI-IR) spectroscopy. This method selectively measures IR spectra of molecular clusters in very high-n Rydberg states (n > 100) utilized in zero kinetic energy (ZEKE) photoelectron and MATI spectroscopy, whose ion...

Photoionization-induced pi <-> H site switching dynamics in phenol(+)-Rg (Rg = Ar, Kr) dimers probed by picosecond time-resolved infrared spectroscopy

Miyazaki, Mitsuhiko ; Sakata, Yuri ; Schütz, Markus ; Dopfer, Otto ; Fujii, Masaaki (2016)

The ionization-induced pi <-> H site switching reaction in phenol(+)-Rg (PhOH+-Rg) dimers with Rg = Ar and Kr is traced in real time by picosecond time-resolved infrared (ps-TRIR) spectroscopy. The ps-TRIR spectra show the prompt appearance of the non-vanishing free OH stretching band upon resonant photoionization of the pi-bound neutral clusters, and the delayed appearance of the hydrogen-bond...

Combined 1D, 2D and 3D micro-XRF techniques for the analysis of illuminated manuscripts

Lachmann, Tim ; van der Snickt, Geert ; Haschke, Michael ; Mantouvalou, Ioanna (2016)

The combination of several micro-XRF analysis modes is presented for the investigation of an illuminated parchment manuscript. With a commercial instrument, conventional micro-XRF spot analysis (0D) and mapping (2D) are performed, yielding detailed lateral elemental information. Depth resolution becomes accessible by mounting an additional polycapillary lens in front of an SDD detector. Quantit...

Structural motifs of 2-(2-fluoro-phenyl)-ethylamine conformers

Mayorkas, Nitzan ; Sachs, Hanan ; Schütz, Markus ; Ishiuchi, Shun-ichi ; Fujii, Masaaki ; Dopfer, Otto ; Bar, Ilana (2016)

Vibronic and vibrational spectra of 2-(2-fluoro-phenyl)-ethylamine (2-FPEA) conformers were measured in a molecular beam by resonant two-photon ionization (R2PI), ultraviolet-ultraviolet hole burning (UV-UV HB) spectroscopy, and ionization-loss stimulated Raman spectroscopy (ILSRS). The measured ILSR spectral signatures in the survey spectra of the amino group region and in the broad spectral r...