A5029567118- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
- Photochemistry and Electron Transfer Studies
- Spectroscopy and Laser Applications
- Molecular Spectroscopy and Structure
- Atmospheric Ozone and Climate
- Mass Spectrometry Techniques and Applications
- Atmospheric chemistry and aerosols
- DNA and Nucleic Acid Chemistry
- Origins and Evolution of Life
- Molecular spectroscopy and chirality
- Analytical Chemistry and Chromatography
- Laser Design and Applications
- Photosynthetic Processes and Mechanisms
- nanoparticles nucleation surface interactions
- Inorganic Fluorides and Related Compounds
- Physics and Engineering Research Articles
- Crystallography and molecular interactions
- Protein Structure and Dynamics
- Free Radicals and Antioxidants
- TiO2 Photocatalysis and Solar Cells
- Fluorine in Organic Chemistry
- Spectroscopy and Chemometric Analyses
- Nanocluster Synthesis and Applications
- Laser-Ablation Synthesis of Nanoparticles
Heinrich Heine University Düsseldorf
2011-2024
Bridge University
2021
Humboldt-Universität zu Berlin
2013
Institute of Biostructure and Bioimaging
2013
University of Duisburg-Essen
2012
University of Bristol
2009
Istituto Nazionale Biostrutture e Biosistemi
2009
Zhejiang University
2007
Center of Advanced European Studies and Research
2005-2006
Shandong University
2006
Biochemical reactions are subject to the particular environmental conditions of planet earth, including solar irradiation. How DNA responds radiation is relevant human health because damage can affect genetic propagation and lead cancer also important for our understanding how life on earth developed. A reductionist approach unravelling detailed photochemistry seeks establish intrinsic properties individual building blocks, followed by extrapolation larger systems, incorporate interactions...
The S1←S0 000 transitions of phenol and the hydrogen bonded phenol(H2O)1 cluster have been studied by high resolution fluorescence excitation spectroscopy. All lines in monomer spectrum are split 56±4 MHz due to internal rotation −OH group about a axis. barrier for this motion is determined ground excited states; V2″=1215 cm−1, V2′=4710 cm−1. rotational constants state agreement with those reported microwave studies. were found be A′=5313.7 MHz, B′=2620.5 C′=1756.08 MHz. region redshifted...
It is proposed that the two Λ-doublet levels of linear molecules with nonzero electronic orbital angular momentum be labeled Λ(A′) and Λ(A″), e.g., Π(A′) Π(A″) for Π states, etc., according to following prescription: All series in which wave function at high J symmetric reflection spatial coordinates electrons plane rotation will designated all values J, those antisymmetric respect denoted Λ(A″). emphasized this notation meant supplement, not replace, accepted spectroscopic e/f labeling...
The vibronic spectrum of laser desorbed and jet cooled guanine consists bands from three different tautomers as revealed by UV–UV IR–UV double resonance spectroscopy. 1-methylguanine, in which the Keto–Enol tautomerism is blocked, shows hole burning spectra 9H-and 7H-Keto form. A comparison pattern demonstrates that built on redmost band at 32 870 cm−1 (electronic origin 0) can be traced back to 9H-Enol tautomer, while origins 0+404 0+1044 stem two Keto tautomers. OH-and NH-stretch...
Autotrophic theories for the origin of metabolism posit that first cells satisfied their carbon needs from CO 2 and were chemolithoautotrophs obtained energy electrons H . The acetyl-CoA pathway fixation is central to view because its antiquity: Among known fixing pathways it only one i) exergonic, ii) occurs in both bacteria archaea, iii) can be functionally replaced full by single transition metal catalysts vitro. In order operate at a pH close 7, however, requires complex multi-enzyme...
We present R2PI spectra of a series purine nucleobases, nucleosides, and related derivatives, including adenine, guanine, guanosine, 2-aminopurine, 2,6-diaminopurine, 9-ethyladenine, 9-methylguanine. compare the results with models involving two interacting excited states, which have been proposed to explain short excited-state lifetime most nucleobases. The amino group in 2 position appears strong effect on potentials, as does any substitution 9 position. This explains very different...
We present resonant two-photon ionization (R2PI) and IR-UV double resonance spectra of the nucleobase adenine seeded in a supersonic jet. show that there are two tautomers which absorb wavelength range 35 400 to 36 700 cm−1. The IR spectra, measured 3200 3700 cm−1via hole burning at 105 (35 824) cm−1, bands 3452 (3437), 3508 (3507/3514) 3569 (3550) we assign symmetric NH2, N–H antisymmetric NH2 stretching vibrations 9H-(7H-) by comparison with ab initio based normal mode calculations....
The vibronic spectra of jet cooled phenol(H2O)7,8 clusters were analyzed with mass selective resonance enhanced two photon ionization (R2PI) and ultraviolet-ultraviolet spectral hole burning (UV-UV SHB). A double technique an infrared (IR) laser as burn (IR-UV SHB) was used to measure the intramolecular OH stretching vibrations mass- isomer-selected clusters. Two isomers phenol(H2O)7 three phenol(H2O)8 could be distinguished via SHB their IR recorded. red- or blueshift electronic origin...
Guanosine monophosphate (GMP) in aqueous solutions has been studied with femtosecond broad-band transient absorption spectroscopy and by quantum-mechanical calculations. The sample was excited at 267 or 287 nm probed between 270 1000 100 fs resolution, for various pH values 2 7. At 2, when the guanine ring is ground-state protonated (GMPH+), we observe isosbestic behavior indicating state-to-state relaxation. relaxation biexponential, τ1 = 0.4 ps, τ2 2.2 followed slower internal conversion...
Phenothiazinyl rhodanylidene acetic acid merocyanine dyes with variable substitution pattern on the peripheral benzene ring were synthesized in good to excellent yields by Knoevenagel condensation of corresponding phenothiazinyl aldehydes and rhodanine-N-acetic acid. The electronic properties investigated cyclic voltammetry, absorption, fluorescence spectroscopy. Electron releasing leads an appreciable lowering oxidation potential, bathochromic shift absorption band, minimization emission...
Pervaporation and gas separation performances of polymer membranes can be improved by crosslinking or addition metal-organic frameworks (MOFs). Crosslinked copolyimide show higher plasticization resistance no significant loss in selectivity compared to non-crosslinked when exposed mixtures CO2/CH4 toluene/cyclohexane. Covalently crosslinked reveal better than ionically systems. Covalent interlacing with 3-hydroxypropyldimethylmaleimide as photocrosslinker investigated situ solution well...
Though all theories for the origin of life require a source energy to promote primordial chemical reactions, nature that drove emergence metabolism at origins is still debated. We reasoned evidence should be preserved in biochemical reactions itself, whereby changes free energy, Δ G , which determine whether reaction can go forward or not, help specify source. By calculating values across conserved and universal core 402 individual synthesize amino acids, nucleotides cofactors from H 2 CO NH...
We present R2PI and IR–UV double resonance spectra of the nucleobase adenine seeded in a supersonic jet. show that there is only one tautomer which absorbs wavelength range 36 050 to 700 cm−1. The IR spectra, measured 3200 3700 cm−1, bands at 3452, 3508 3569 we assign symmetric NH2 , N–H antisymmetric stretching vibrations single adenine. compare experimental with ab initio based normal mode calculations. observed most probably 9H amino-form
In this paper we present detailed R2PI spectra with IR–UV and UV–UV double resonance measurements of the guanine dimer (GG) its methylated derivatives. We show that there are two isomers GG in investigated wavelength range from 32565 to 33600 cm−1. were able assign specific structures based on comparison intermolecular vibronic patterns dimers without methylation, analysis IR OH NH stretching vibrations ab initio calculated stabilities vibrational frequencies. both moieties keto tautomeric...
We present R2PI, IR–UV and UV–UV double resonance measurements of the guanine–cytosine (G–C) dimer formed in a supersonic jet. show that there is only one isomer G–C investigated wavelength range from 33200 to 34100 cm−1. assigned observed specific structure, based on comparisons IR spectra G C monomers with OH NH stretching vibrations ab initio-calculated vibrational frequencies stabilities. The cluster exhibits an HNH⋯O/NH⋯N/CO⋯HNH bonding similar Watson–Crick base pair but as enol...
The peptides Trp-Gly, Gly-Trp and Trp-Gly-Gly were investigated by UV–UV IR–UV hole burning spectroscopy. Solid samples of the three vaporised into an argon jet laser desorption. spectra different conformers assigned comparison with tryptophan [Snoek et al., Phys. Chem. Phys., 2001, 3, 1819], free peptide bond in N-acetyl methyl amide [Dian J. 2002, 117, 10 688] ab initio calculations performed at DFT B3LYP 6-31G(d,p) level. Apart from NH⋯NH2 interaction, backbone one conformer each...
By using laser-induced heating, we prepared Au−Ag nanoalloys via three different procedures: (i) mixture of Au nanoparticles and Ag+ ions irradiated by a 532 nm laser, (ii) Ag (iii) 355 laser. Procedure i is advantageous for the production spherical alloy nanoparticles; in procedures ii iii, with sintered structure have been obtained. The morphology obtained depends not only on laser wavelength but also concentration initial mixture. When total increased, large-scale interlinked networks...
Abstract To understand the intrinsic properties of peptides, which are determined by factors such as intramolecular hydrogen bonding, van der Waals bonding and electrostatic interactions, conformational landscape isolated protein building blocks in gas phase was investigated. Here, we present IR‐UV double‐resonance spectra jet‐cooled, uncapped peptides containing a tryptophan (Trp) UV chromophore 1000–2000 cm −1 spectral range. In series Trp, Trp‐Gly Trp‐Gly‐Gly (where Gly stands for...