A5080546903- Mass Spectrometry Techniques and Applications
- Advanced Chemical Physics Studies
- Carbohydrate Chemistry and Synthesis
- Chemical Synthesis and Analysis
- Photonic and Optical Devices
- Advanced X-ray Imaging Techniques
- Laser-Matter Interactions and Applications
- Click Chemistry and Applications
- Porphyrin and Phthalocyanine Chemistry
- X-ray Spectroscopy and Fluorescence Analysis
- Marine Sponges and Natural Products
- Ion-surface interactions and analysis
- Advanced MEMS and NEMS Technologies
- Surface Chemistry and Catalysis
- Microbial Natural Products and Biosynthesis
- Synthesis and Catalytic Reactions
- Software Engineering and Design Patterns
- Enzyme Structure and Function
- Peptidase Inhibition and Analysis
- Phytochemical Studies and Bioactivities
- Astrophysics and Star Formation Studies
- Photodynamic Therapy Research Studies
- Photoreceptor and optogenetics research
- Advanced Electron Microscopy Techniques and Applications
- Mechanical and Optical Resonators
Deutsches Elektronen-Synchrotron DESY
2018-2022
Leibniz Institute of Plant Biochemistry
2009-2013
Karlsruhe Institute of Technology
2013
Institut für Mikroelektronik- und Mechatronik-Systeme
2012
Leibniz Association
2005
The first total synthesis of tubulysin B is described. aziridine route to tubuphenylalanine (Tup) the D/U-series could not be transferred tubutyrosine (blue moiety). Therefore, (Tut) was synthesized by a Wittig olefination/diastereoselective catalytic reduction sequence. Interestingly, C-2 epimer has cytotoxic activity almost identical natural diastereomer.
The spectral detection efficiency and the dark count rate of superconducting nanowire single-photon detectors (SNSPD) have been studied systematically on made from thin NbN films with different chemical compositions. Reduction nitrogen content in 4 nm thick results a decrease rates more than two orders magnitude red shift cut-off wavelength hot-spot SNSPD response. observed phenomena are explained by an improvement uniformity that has confirmed resistivity increase ratio measured critical...
Gas-phase activation and dissociation studies of biomolecules, proteins their non-covalent complexes using X-rays hold great promise for revealing new insights into the structure function biological samples. This is due to unique properties X-ray molecular interactions, such as site-specific rapid ionization. In this perspective, we report discuss first proof-of-principle X-ray-induced native samples ranging from small 17 kDa monomeric up large 808 protein assemblies conducted at a...
Gas-phase activation and dissociation studies of biomolecules, proteins their non-covalent complexes using X-rays hold great promise for revealing new insights into the structure function biological samples. This...
A facile and flexible approach for the preparation of macrocyclic molecules containing different carbohydrate moieties is presented, employing reaction cascade: click-dimerization ring-closing metathesis.
Inner-shell photoelectron spectroscopy provides an element-specific probe of molecular structure, as core-electron binding energies are sensitive to the chemical environment. Short-wavelength femtosecond light sources, such Free-Electron Lasers (FELs), even enable time-resolved site-specific investigations photochemistry. Here, we study ultraviolet photodissociation prototypical chiral molecule 1-iodo-2-methylbutane, probed by extreme-ultraviolet (XUV) pulses from Free-electron LASer in...
Site-selective dissociation induced by core photoexcitation of biomolecules is key importance for the understanding radiation damage processes and dynamics its promising use as "chemical scissors" in various applications. However, identifying products site-selective large molecules challenging at carbon, nitrogen, oxygen edges because high recurrence these atoms related chemical groups. In this paper, we present observation sulfur L-edge gas-phase peptide methionine enkephalin, which...
Ion yields following X-ray absorption of the cationic series NHy+ (y = 0-3) were measured to identify characteristic resonances in energy range atomic nitrogen K-edge. Significant changes position observed depending on number hydrogen atoms bound central atom. Configuration interaction (CI) calculations performed obtain line assignments frame molecular group theory. To validate calculations, our assignment for cation N+, as a reference, was compared with published theoretical and experimental data.
The synthesis of multivalent neoglycoconjugates with 2,6-diamino-2,6-dideoxyglucose is accomplished by a flexible Ugi multicomponent approach leading to mono-, di- and tri-valent carbohydrate clusters.
We investigate the detection efficiency of a spiral layout superconducting nanowire single-photon detector. The design is less susceptible to critical current reduction in sharp turns than conventional meander design. Detector samples with different widths from 100 300 nm are patterned 4-nm-thick NbN film deposited on sapphire substrates. I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> at 4.2 K for spiral, meander, and single-bridge...
Extreme ultraviolet (XUV) and X-ray free-electron lasers enable new scientific opportunities. Their ultra-intense coherent femtosecond pulses give unprecedented access to the structure of undepositable nanoscale objects transient states highly excited matter. In order probe ultrafast complex light-induced dynamics on relevant time scales, multi-purpose end-station CAMP at laser FLASH has been complemented by novel multilayer-mirror-based split-and-delay unit DESC (DElay Stage for CAMP)...
We have investigated the photoionization and photofragmentation yields of gas-phase multiply protonated melittin cations for photon energies at K-shell absorption edges carbon, nitrogen, oxygen. Two similar experimental approaches were employed. In both experiments, mass selected [melittin+qH]q+ (q=2-4) ions accumulated in radiofrequency ion traps. The trap content was exposed to intense beams monochromatic soft X-ray photons from synchrotron beamlines photoproducts analyzed by means...
Near-edge X-ray absorption mass spectrometry (NEXAMS) is an action-spectroscopy technique of growing interest for investigations into the spatial and electronic structure biomolecules. It has been used successfully to give insights different aspects photodissociation peptides probe conformation proteins. a current question whether fragmentation pathways are sensitive toward effects conformational isomerism, tautomerism, intramolecular interactions in gas-phase peptides. To address this...
The local electronic structure of the metal-active site and deexcitation pathways metalloporphyrins are crucial for numerous applications but difficult to access by commonly employed techniques. Here, we applied near-edge X-ray absorption mass spectrometry quantum-mechanical restricted active space calculations investigate isolated cobalt(iii) protoporphyrin IX cation (CoPPIX+) its upon resonant at cobalt L-edge. experiments were carried out in gas phase, thus allowing control over chemical...
Abstract VUV action spectroscopy has recently gained interest for the study of peptides and proteins. However, numerous aspects fundamental processes involved in photodissociation are yet to be understood. It can, example, expected that sulfur-containing amino-acid residues have a significant impact on dissociation following photoionization because their potential involvement transport electron holes In order investigate influence methionine residue small peptide gas-phase protonated...
Synopsis (X-ray) free-electron lasers are employed to site specifically interrogate atomic fragments during ultra-fast photolysis of chiral molecules via time-resolved photoelectron circular dichroism.
We investigated the photoionization and fragmentation of isolated metal protoporphyrin IX cations (MPPIX
Synopsis In the interstellar medium polycyclic aromatic hydrocarbon molecules (PAH) are exposed to strong ionizing radation leading complex organic photochemistry. We investigated these ultrafast fragmentation reactions after ionization of PAHs phenanthrene, fluorene and pyrene at a wavelength 30.3 nm using pump probe spectroscopy free electron laser. observe double afterwards hydrogen abstraction acetylene loss with characteristic time scales for reaction processes below one hundred femtoseconds.