Moritz M Sokolowski

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Long-duration gamma-ray bursts (GRBs) release copious amounts of energy across the entire electromagnetic spectrum, and so provide a window into the process of black hole formation from the collapse of massive stars. Previous early optical observations of even the most exceptional GRBs (990123 and 030329) lacked both the temporal resolution to probe the(More)
Normal incidence x-ray standing wave experiments and density functional theory reveal that 3,4,9,10-perylene-tetracarboxylic-dianhydride chemisorbs on Ag(111) in a nonplanar but vertically distorted configuration. The carboxylic O atoms are 0.18 +/- 0.03 angstroms closer to the surface than the perylene core. The distortion is related to weak, local bonds(More)
The guided modes of sub-wavelength diameter air-clad optical fibers exhibit a pronounced evanescent field. The absorption of particles on the fiber surface is therefore readily detected via the fiber transmission. We show that the resulting absorption for a given surface coverage can be orders of magnitude higher than for conventional surface spectroscopy.(More)
We report on the nucleation and growth of tetracene in a thin liquid film which is continuously supersaturated by vapor deposition of molecules onto the film. In a first stage, nucleation and fast anisotropic two-dimensional dendritic growth occurs. In a second stage, the dendrites coarsen into pallet-shaped crystals. These are highly oriented with respect(More)
Tetracene (Tc) and rubrene (Rub) are two prototype fluorescent molecules. Both molecules exhibit the same ‘fluorescent backbone’, but due to the additional phenyl groups, the backbone of Rub is twisted, whereas it is planar for Tc. In agreement with earlier investigations, optical spectroscopy of the respective solutions reveals that the S0 → S1 transition(More)
The width and asymmetry of the line shape of the optical transition of a sample of two dimensional (2D) molecular J-aggregates was found to be related to a finite-size effect. The 2D aggregates were domains of the ordered monolayer of the fluorescent dye molecule 3,4,9,10-perylenetetracarboxylic acid dianhydride on a KCl(100) surface. Fluorescence and(More)
We performed fluorescence (FL) and fluorescence excitation (FLE) spectroscopy on the model molecule perylene-3,4,9,10-tetracarboxyl acid dianhydride (PTCDA) for very low coverages (below 1% of a monolayer) on thin (100) oriented KCl films. Two different states of PTCDA molecules can be distinguished in the spectra: an initial state, which is observed(More)
Aggregates of interacting molecules can exhibit electronically excited states that are coherently delocalized over many molecules. This can lead to a strong enhancement of the fluorescence decay rate which is referred to as superradiance (SR). To date, the temperature dependence of SR is described by a 1/T law. Using an epitaxial dye layer and a(More)
We have investigated the adsorption of perylene-3,4,9,10-tetracarboxylic acid dianhydride (PTCDA) on the clean and on the oxygen pre-covered Cu(100) surface [referred to as (√2 × 2√2)R45° - 2O/Cu(100)] by scanning tunneling microscopy (STM) and low energy electron diffraction (LEED). Our results confirm the (4√2 × 5√2)R45° superstructure of PTCDA/Cu(100)(More)
The organic semiconductor molecule 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) exhibits two adsorption states on the Ag(111) surface: one in a metastable disordered phase, prepared at low temperatures, the other in the long-range ordered monolayer phase obtained at room temperature. Notably, the two states differ substantial in their vertical(More)