A5018796627- Advanced Chemical Physics Studies
- Laser-Matter Interactions and Applications
- Spectroscopy and Laser Applications
- Advanced X-ray Imaging Techniques
- Laser-Plasma Interactions and Diagnostics
- Molecular Junctions and Nanostructures
- Spectroscopy and Quantum Chemical Studies
- Laser Design and Applications
- Atomic and Molecular Physics
- Advanced Electron Microscopy Techniques and Applications
- Cold Atom Physics and Bose-Einstein Condensates
- Mass Spectrometry Techniques and Applications
- Atmospheric Ozone and Climate
- Crystallization and Solubility Studies
- X-ray Spectroscopy and Fluorescence Analysis
- Quantum, superfluid, helium dynamics
- Particle Accelerators and Free-Electron Lasers
- Advanced Fiber Laser Technologies
- Electron and X-Ray Spectroscopy Techniques
- Ion-surface interactions and analysis
- Graphene research and applications
- Semiconductor materials and devices
- Photochemistry and Electron Transfer Studies
- Laser-induced spectroscopy and plasma
- Surface and Thin Film Phenomena
University of Münster
2016-2025
Center for NanoScience
2018-2025
CeNTech
2006-2024
Purdue University West Lafayette
2018
University of Warsaw
2014
Weizmann Institute of Science
2014
University of Modena and Reggio Emilia
2014
University of Pittsburgh
2014
Fraunhofer Institute for Wind Energy Systems
1995-2009
University of Buenos Aires
2005
In electron-transfer processes, spin effects normally are seen either in magnetic materials or systems containing heavy atoms that facilitate spin-orbit coupling. We report spin-selective transmission of electrons through self-assembled monolayers double-stranded DNA on gold. By directly measuring the transmitted with a Mott polarimeter, we found polarizations exceeding 60% at room temperature. The spin-polarized photoelectrons were observed even when generated unpolarized light. selectivity...
We report on a bottom-up approach of the selective and precise growth subnanometer wide straight chevron-type armchair nanoribbons (GNRs) stepped Au(788) surface using different specific molecular precursors. This process creates spatially well-aligned GNRs, as characterized by STM. High-resolution direct inverse photoemission spectroscopy occupied unoccupied states allows determination energetic position momentum dispersion electronic revealing existence band gaps several electron volts for...
Significance The role of the electron spin in chemistry and biology has been receiving much attention because a plausible relation to electromagnetic field effects on living organisms. Part difficulty studying subject arises from lack physical model that can rationalize these phenomena. Recently chiral-induced selectivity effect was observed transmission through organic molecules. question is what extent takes place proteins. In present study, we probed bacteriorhodopsin embedded its native...
The interaction of low-energy photoelectrons with well-ordered monolayers enantiopure helical heptahelicene molecules adsorbed on metal surfaces leads to a preferential transmission one longitudinally polarized spin component, which is strongly coupled the sense molecules. Heptahelicene, composed only carbon and hydrogen atoms, exhibits single turn but shows excess in longitudinal polarization about P Z = 6 8% after initially balanced left- right-handed electrons. Insight into electronic...
We report on the observation of chirality induced spin selectivity for electrons transmitted through monolayers oligopeptides, both energies above vacuum level as well bound and conducted a single molecule. The dependence molecular length is measured in an electrochemical cell photoemission spectrometer photoelectrons. absolute polarization are similar energy regimes. Single molecule conductance studies provide effective charge transport barrier between two channels it found to be order 0.5 eV.
Desorption of NO molecules from a Pd(111) surface induced by femtosecond visible laser pulses has been investigated in real time. The measurements, accomplished means two-pulse correlation scheme, reveal subpicosecond response findings indicate that the desorption arises coupling to nonequilibrium electronic excitation substrate.
This work demonstrates the chiral-induced spin selectivity effect for inorganic copper oxide films and exploits it to enhance chemical in electrocatalytic water splitting. Chiral CuO are electrodeposited on a polycrystalline Au substrate, their filtering electrons is demonstrated using Mott polarimetry analysis of photoelectrons. known act as an electrocatalyst oxygen evolution reaction; however, also generates side products such H2O2. We show that chiral selective O2; H2O2 generation...
We report on the dynamics of ultrafast heating in cryogenic hydrogen initiated by a ≲300 fs, 92 eV free electron laser x-ray burst. The rise scattering amplitude from second pulse probes transition dense molecular to nearly uncorrelated plasmalike structure, indicating an electron-ion equilibration time ∼0.9 ps. agrees with radiation hydrodynamics simulations based conductivity model for partially ionized plasma that is validated two-temperature density-functional theory.
The demand for spatially structured ultrashort beams at shorter wavelengths is high, and their adaptability in potential applications such as imaging, metrology, attosecond science undeniable. In this work, we present the generation of high-harmonic array beams. We utilize near-infrared wavelength pump source to reliably generate extreme-ultraviolet tenth harmonic wavelength. showed shape-invariant free space propagation exhibited a self-healing ability against adverse spatial effects...
The oxygen reduction reaction (ORR) in acidic media suffers from sluggish kinetics, primarily due to the spin-dependent electron transfer involved. direct generation of spin-polarized electrons at catalytic surfaces remains elusive, and underlying mechanisms are still controversial lack intrinsically chiral catalysts. To address this challenge, we investigate topological homochiral PdGa (TH PdGa) crystals with for ORR. Through spin-resolved photoemission spectroscopy theoretical simulations,...
The temporal coherence properties of soft x-ray free electron laser pulses at FLASH are measured 23.9 nm by interfering two timedelayed partial beams directly on a CCD camera.The obtained wave front beam splitting in an autocorrelator operating photon energies from hν = 30 to 200 eV.At zero delay visibility (0.63 ± 0.04) is measured.The one reveals time 6 fs nm.The further displays non-monotonic decay, which can be rationalized the presence multiple pulse structure.
The dynamics of the photodissociation NO2 molecule into NO(X 2Π1/2,3/2; v, J)+O(3P0,1,2) at N2 laser wavelength 337 nm (=29 965 cm−1) has been investigated by photofragment spectroscopy room temperature in bulk. internal energy distribution 2Π) fragment analyzed state selectively with respect to electronic (Ω=1/2, 3/2) and rotation–vibration (v, J) using induced fluorescence excitation for NO observation A–X transition ultraviolet. rotational vibrational populations strongly deviate from...
The pulse duration of soft x-ray free-electron laser (FEL) radiation is directly measured by time-resolved observation doubly charged helium ions at 51.8 eV. A wave front splitting autocorrelator produces two correlated FEL pulses with a resolution better than femtosecond. In the interesting intensity range from ${10}^{13}$ to ${10}^{16}\text{ }\text{W}/{\text{cm}}^{2}$ direct and sequential double ionization contribute ion yield which has significant influence on correlation width, being...
We present new experimental and theoretical results for reactive scattering of dihydrogen from Cu(100). In the experiments, associative desorption H2 is studied in a velocity resolved final rovibrational state selected manner, using time-of-flight techniques combination with resonance-enhanced multi-photon ionization laser detection. Average energies rotational quadrupole alignment parameters were obtained this way number (v = 0, 1) states, v being vibrational quantum number. Results...
The average temporal (longitudinal) and spatial (transverse) coherence of free-electron-laser pulses in the extreme ultraviolet at FLASH is measured by interfering two time-delayed partial beams directly on a CCD camera. Wavelengths between $\ensuremath{\lambda}=32\text{ }\text{ }\mathrm{nm}$ $\ensuremath{\lambda}=8\text{ are examined. A decrease time for fundamental wavelengths from ${\ensuremath{\tau}}_{c}=(6\ifmmode\pm\else\textpm\fi{}0.5)\text{ }\mathrm{fs}$ 32 nm to...
The charge rearrangement in dissociating I_{2}^{n+} molecules is measured as a function of the internuclear distance R using extreme ultraviolet pulses delivered by free-electron laser Hamburg. Within an pump-probe scheme, first pulse initiates dissociation multiply ionizing I_{2}, and delayed probe further ionizes one two fragments at given time, thus triggering well-defined R. electron transfer between monitored analyzing delay-dependent ion kinetic energies states. experimental results...
One of the most challenging tasks for extreme ultraviolet, soft and hard x-ray free-electron laser photon diagnostics is precise determination pulse duration, which typically in sub 100 fs range. Nine different methods, able to determine such ultrashort durations, were compared experimentally at FLASH, self-amplified spontaneous emission DESY Hamburg, order identify advantages disadvantages methods. Radiation pulses a wavelength 13.5 24.0 nm together with corresponding electron bunch...
For time-resolved extreme ultraviolet (XUV) pump–XUV probe experiments at the Free electron LASer in Hamburg (FLASH), a split-and-delay unit (SDU) has been built. It is implemented beamline BL2 which provides focal spot size of about 20 μm diameter experiment. The beam divided geometrically into two paths can be delayed from −3 to +15 ps with respect each other. transmission up 200 eV photon energy above 35% one path and 74% latter transmits XUV again 305 570 (>1% transmission). Thus almost...
High-harmonic generation is widely used for providing extreme ultraviolet radiation in attosecond science. Such experiments include photoelectron spectroscopy, diffractive imaging, or the investigation of spin dynamics. Many applications are restricted by a low photon flux which originates from efficiency process. In this article an effective method based on quasi-phase-matched high harmonics spatially structured, laser ablated plasma demonstrated. Through proper dimensioning structure,...
The chirality-induced spin selectivity (CISS) effect facilitates a paradigm shift for controlling the outcome and efficiency of spin-dependent chemical reactions, example, photoinduced water splitting. While phenomenon is established in organic chiral molecules, its emergence but inorganic, nonmolecular materials not yet understood. Nevertheless, inorganic spin-filtering offer favorable characteristics, such as thermal stability, over organic, molecular filters. Chiral cupric oxide (CuO)...