A5075246397- Nuclear reactor physics and engineering
- Nuclear Materials and Properties
- Photochromic and Fluorescence Chemistry
- Conducting polymers and applications
- Organic Electronics and Photovoltaics
- Photochemistry and Electron Transfer Studies
- Radioactive element chemistry and processing
- Spectroscopy and Quantum Chemical Studies
- Photoreceptor and optogenetics research
- Photosynthetic Processes and Mechanisms
- Fusion materials and technologies
- Luminescence and Fluorescent Materials
- Porphyrin and Phthalocyanine Chemistry
- Supramolecular Self-Assembly in Materials
- Nuclear and radioactivity studies
- Advanced Fluorescence Microscopy Techniques
- Nuclear Physics and Applications
- Organic Light-Emitting Diodes Research
- Analytical Chemistry and Sensors
- Quantum, superfluid, helium dynamics
- Photoacoustic and Ultrasonic Imaging
- Ion-surface interactions and analysis
- Nuclear Engineering Thermal-Hydraulics
- Advanced biosensing and bioanalysis techniques
- Enzyme Structure and Function
Nuclear Research and Consultancy Group
2011-2024
Lund University
2005-2010
University of Groningen
2002-2007
Humboldt-Universität zu Berlin
2003-2007
Freie Universität Berlin
2004
Self-assembled cylindrical aggregates of amphiphilic carbocyanine dye molecules are interesting candidates for synthetic light-harvesting systems and electronic energy transport wires. To be able to optimize the properties such systems, detailed information on molecular structure as well static dynamic optical is required. We report cryo-transmission electron microscopy (cryo-TEM) experiments 3,3'-bis(3-sulfopropyl)-5,5',6,6'-tetrachloro-1,1'-dioctylbenzimidacarbocyanine (C8S3) that reveal a...
The reversible photoconversion of self-assembling dithienylcyclopentene photochromic switches between an aggregated and nonaggregated state is manifest at the macroscopic level by a fully sol–gel phase transition results in spatially confined structure formation inhomogeneous optical field. reversibility aggregation exploited dynamic pattern (see images).
The amphiphilic dye 3,3'-bis(2-sulfopropyl)-5,5',6,6'-tetrachloro-1,1'-dioctylbenzimidacarbocyanine (C8S3) self-aggregates in aqueous solution to form tubular J-aggregates with a diameter of 17.0 +/- 0.5 nm, wall thickness approximately 4 and length exceeding several hundred nanometers. absorption spectrum shows the typical features expected for sharp red-shifted bands. Morphological investigations using cryo-transmission electron microscopy (cryo-TEM) spectroscopic reveal high stability...
A novel technique, two-dimensional (2D) polarization single-molecule imaging, is presented. It based on measurements and analysis of fluorescence intensity as a function excitation emission angles. The technique allows recording full information the steady-state properties fluorescent objects. particularly suitable for application to single multichromophoric systems (molecules or nanoparticles) with energy transfer (ET) between different chromophores (e.g., pi-conjugated polymer chains). 2D...
The switching behavior of 1,2-bis(5-phenyl-2-methylthien-3-yl)cyclopentene is studied by means polarization selective nonlinear optical spectroscopy and time-dependent density functional theory. combined information from the observed population orientational dynamics together with results theoretical calculations show that on a subpicosecond time scale rapid mixing relaxation electronic states occur, before takes place. Such preswitching was not in detail these systems before. Then, process...
Light-emitting electrochemical cells offer efficient light-emission but suffer from short operational lifetimes. The latter is demonstrated to stem photoinduced chemical reactions involving the conjugated polymer in light-emitting p–n junction region, as evidenced by, e.g., optical and Raman microscopy (see figure). It possible alleviate extent of these side reactions, accordingly improve lifetime, by improved heat control region.
The amyloid-like fibril is a biomolecular nanowire template of very high stability. Here we describe the coordination conjugated polyelectrolyte, poly(thiophene acetic acid) (PTAA), to bovine insulin fibrils with widths <10 nm and lengths up more than 10 microm. Fibrils complexed PTAA are aligned on surfaces through molecular combing transfer printing. Single-molecule spectroscopy techniques applied chart spectral variation in emission these wires. When results combined analysis polarization...
The switching behavior of 1,2-bis(5-phenyl-2-methylthien-3-yl)perfluorocyclopentene and its nonfluorinated (perhydro) analogue are compared. For both molecules, the dynamics after optical excitation can be separated into three regimes: preswiching due to excited state mixing; ring closure itself; postswitching related vibrational cooling. fluorinated version switches faster than by about a factor 4.7. This is explained electronic level shifts near crossing region between S(1) S(0) potential...
Single chains of conjugated polymers e.g. MEH-PPV (poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene) have become interesting objects for single molecule spectroscopy (SMS) studies. However, most the experiments so far were performed without full awareness isolation status polymer in host matrices. We used steady-state and time-resolved fluorescence methods 2D polarization imaging technique to unravel isolation/aggregation spin-coated films prepared at different conditions. It turned...
Abstract Various substituted phenylthienyl perhydro‐ and perfluorocyclopentenes have been synthesized in order to compare their spectroscopic photochromic properties. The difference the electron densities of central cyclopentene moieties perhydrocyclopentene perfluorocyclopentene molecular switches has only a small effect on absorption maxima electronic spectra, but causes some subtle changes substituent solvatochromic effects. behaviour is remarkably similar, both type combine excellent...
Die reversible Photoumwandlung selbstorganisierender photochromer Dithienylcyclopenten-Schalter zwischen einem aggregierten und nichtaggregierten Zustand zeigt sich auf makroskopischem Niveau als vollständig reversibler Sol-Gel-Phasenübergang hat in inhomogenen optischen Feld eine räumlich beschränkte Strukturbildung zur Folge. Reversibilität der Aggregation wird für dynamische Musterbildung genutzt (siehe Bilder).
An electric field oscillating at a frequency ∼1 Hz is found to induce strong modulation of the fluorescence intensity single poly[2-methoxy,5-(2'-ethyl-hexyloxy)-p-phenylene vinylene] (MEH-PPV) molecules (MW ∼ 106) embedded in poly(methyl methacrylate) (PMMA) matrix. The MEH-PPV polymer chains are carefully isolated from electrodes avoid effects injection. In polystyrene matrix, modulations on average much less pronounced. difference depth can be explained terms lower field-induced exciton...
The changes in the optical properties and morphology of J-aggregates formed by 3,3'-bis(3-carboxypropyl)-5,5',6,6'-tetrachloro-1,1'-dioctylbenzimidacarbocyanine dye (C8O3) aqueous solution that are induced addition poly(vinyl alcohol) (PVA) were investigated spectroscopy cryo-transmission electron microscopy (cryo-TEM). Upon increase PVA concentration, aggregates evolve show a similar tubular as those pure but with new spectroscopic features. absorption spectrum modified differs from...
Fluctuations in the fluorescence polarization degree and direction are reported for first time single conjugated polymer molecules embedded a polystyrene matrix at room temperature. The molecule, polythiophene derivative, clearly emits as multi-chromophore ensemble showing that energy does not funnel to any specific low-energy trap. instead originates from thermally populated exciton states with different relative orientations of transition dipole moments. fluctuations explained terms...
Americium is a strong contributor to the long term radiotoxicity of high activity nuclear waste. Transmutation by irradiation in reactors long-lived nuclides like 241Am therefore an option for reduction waste packages be stored repository. The SPHERE experiment latest series European experiments on americium transmutation (e.g. EFTTRA-T4, EFTTRA-T4bis, HELIOS, MARIOS) performed HFR (High Flux Reactor). carried out framework 4-year project FAIRFUELS EURATOM 7th Framework Programme (FP7)....
The static and time‐resolved optical response of 5, 5 ′ , 6, 6 ‐tetrachlorobenzimidacarbocyanine chromophore‐based tubular double‐wall molecular aggregates is studied. linear dichroism absorption spectra have the same basic structure for all investigated essentially showing a set narrow highly polarized bands originating from inner outer wall excitations. exact positions strengths are influenced by choice side groups various additives. Time‐resolved fluorescence measurements show substantial...
Energy transfer in a newly synthesized coumarin−tetraphenylporphyrin donor−acceptor system was studied by time- and frequency-resolved fluorescence spectroscopy. The energy kinetics shown to be fast (transfer time ca. 500 fs) efficient (quantum yield 97%). influence of interactions between excitations on the dynamics intensity-dependent experiments. Although annihilation occurs for high irradiation doses, this does not affect observed transients. A kinetic model constructed explain these...