Refine
Has Fulltext
- yes (236)
Year of publication
Document Type
- Postprint (236) (remove)
Keywords
- LIBS (4)
- anomalous diffusion (4)
- living cells (4)
- nanoparticles (4)
- DNA origami (3)
- Diodenlaserspektroskopie (3)
- Fluoreszenz-Resonanz-Energie-Transfer (3)
- Immunoassay (3)
- Kohlendioxid (3)
- Lumineszenz (3)
- biomaterials (3)
- crystal structure (3)
- infection pathway (3)
- ligand (3)
- luminescence (3)
- models (3)
- quantum dots (3)
- shape (3)
- structure elucidation (3)
- surface (3)
- water (3)
- 3D printing (2)
- DNA radiation damage (2)
- Energietransfer (2)
- Europium (2)
- FRET (2)
- Fluorescence spectroscopy (2)
- Isotopenverhältnis (2)
- Juvenile hormone (2)
- Leguminosae (2)
- PCA (2)
- Quantenpunkt (2)
- adsorption (2)
- aqueous-solution (2)
- arsenolipids present (2)
- assemblies (2)
- biodegradable polymers (2)
- biomass (2)
- biomineralization (2)
- calcium phosphate (2)
- carbohydrates (2)
- carbon dioxide (2)
- carbon monoxide (2)
- carbon-dioxide (2)
- carbon-dioxide capture (2)
- cellulose (2)
- chitosan (2)
- cod-liver (2)
- composites (2)
- copolymers (2)
- diode laser spectroscopy (2)
- dye removal (2)
- dynamics (2)
- fatty-acids (2)
- ferroelectricity (2)
- films (2)
- heteroatoms (2)
- hybrid perovskites (2)
- hydrogel (2)
- identification (2)
- in-situ (2)
- inorganic chemistry (2)
- intracellular-transport (2)
- ionic conductivity (2)
- ionic liquid (2)
- ionic liquids (2)
- isomerization (2)
- langevin equation (2)
- low-energy electrons (2)
- manganese (2)
- metal-organic frameworks (2)
- methyl orange (2)
- methylene blue (2)
- mixtures (2)
- molecules (2)
- nanostructures (2)
- phase-transitions (2)
- photoisomerization (2)
- photovoltaic materials (2)
- physiological consequences (2)
- poly(lactic acid) (2)
- polysoaps (2)
- polyzwitterion (2)
- polyzwitterions (2)
- proteins (2)
- random-walks (2)
- reduction (2)
- resonance energy-transfer (2)
- ring-opening polymerization (2)
- salts (2)
- sclerotization (2)
- sensitivity (2)
- simulations (2)
- single-particle tracking (2)
- size (2)
- soil (2)
- sorption (2)
- synthesis (2)
- system (2)
- systems (2)
- visible-light (2)
- water treatment (2)
- zinc (2)
- (S)-Elatadihydrochalcone (1)
- (S)-Lupinifolin 4´-methyl ether (1)
- 1,2-dithiooxalate (1)
- 11-mercaptoundecanoic acid (1)
- 2-Azaspiro[4.5]deca-1-ones (1)
- 2D-LC-MS/MS (1)
- 3-color fret (1)
- 3-mercaptopropionic acid (1)
- 315 nm (1)
- 473 nm (1)
- 946 nm (1)
- AOT bilayer (1)
- ATCUN motif (1)
- Absorption (1)
- Absorptionsspektroskopie (1)
- Acids (1)
- AgI (1)
- Amphiphiles (1)
- Amphiphilic Polymers (1)
- Amphiphilic polymers (1)
- Biological activity (1)
- Biophotonik (1)
- Biosynthesis (1)
- Bodengas (1)
- Bodenschutz (1)
- C-reactive (1)
- Caenorhabditis elegans (1)
- Cd-free (1)
- Cellulose (1)
- Cereals (1)
- Chitinase (1)
- Chitosan (1)
- Cis- and trans-form (1)
- Configuration (1)
- Confocal microscopy (1)
- Conformation (1)
- Corpora allata (1)
- DNA damage response (1)
- DNA repair (1)
- DNA strand breaks (1)
- Derris trifoliata (1)
- Electrochemistry (1)
- Energy Transfer (1)
- Enzyme (1)
- Enzyme inhibitor (1)
- Flavanone (1)
- Fluorescence imaging (1)
- Fluorescent probes (1)
- Fluoreszenzspektroskopie (1)
- Fokker-Planck equations (1)
- Formate (1)
- Fungi (1)
- Förster Resonanz Energie Transfer (1)
- Förster resonance energy transfer (1)
- Förster-Resonanz-Energie-Transfer (1)
- G quadruplexes (1)
- Galactosides (1)
- Glycoconjugates (1)
- Glycopeptides (1)
- Gold nanoparticles (1)
- Grundwasserschutz (1)
- HDAC1 (1)
- Huminstoffe (1)
- Hyalophora cecropia (1)
- Hybrid material (1)
- ITC (1)
- In vitro (1)
- InP (1)
- InPZnS (1)
- Ion mobility spectrometry (1)
- Ionic liquid (1)
- Ionic liquids (1)
- Isotop (1)
- Isotope ratio (1)
- Isotopie (1)
- JH-III-specific carrier protein (1)
- Janus droplets (1)
- Juvenile hormone analogue (1)
- Kinetically controlled nanocrystal growth (1)
- Kohlenmonoxid (1)
- LCPs (1)
- Lactams (1)
- Lanthanoide (1)
- Laser (1)
- Leptinotarsa decemlineata (1)
- Lichtstreuung (1)
- Locust (1)
- Locusta migratoria (1)
- Luminescence (1)
- Lupinifolin (1)
- MALDI-TOF mass spectrometry (1)
- MS (1)
- Micellar polymers (1)
- Modified mycotoxins (1)
- Monolayers (1)
- Multi-method (1)
- Mycotoxins (1)
- N-acetyldopamine (1)
- NIR spectroscopy (1)
- NMR structure (1)
- Nanoparticles (1)
- Nanopartikel (1)
- Nanotriangles (1)
- Neodym-YAG-Laser (1)
- NiTi (1)
- O-methyltransferase (1)
- OTDR (1)
- Oligosaccharides (1)
- Optode (1)
- Orthoptera (1)
- PAH (1)
- PEI coating (1)
- PLA (1)
- PLS regression (1)
- PLSR (1)
- Pesticides (1)
- Pestizid (1)
- Phytopathogens (1)
- Pickering emulsions (1)
- Podanthus mitiqui (1)
- Polyampholytes (1)
- Polymerizable surfactant (1)
- Precipitation (1)
- Prozesskontrolle (1)
- QDs (1)
- Quantum Dot (1)
- Quartz Crystal (1)
- REMPI (1)
- RP-HPLC (1)
- RUNX2 (1)
- Rod-like Polymers (1)
- SAK (1)
- SEM (1)
- SERS (1)
- SERS enhancement factor (1)
- Salts (1)
- Sauerstoff (1)
- Schädlingsbekämpfung (1)
- Seedpods (1)
- Sensorik (1)
- Serum (1)
- Stability of LB Films (1)
- Steroid esters (1)
- Summenparameter (1)
- Synthesis and processing (1)
- Tephrosia elata (1)
- TiO2 nanoparticles (1)
- UVR (1)
- Untersuchung (1)
- X-ray diffraction (1)
- X-ray structure (1)
- [4+2] cycloaddition (1)
- [N]phenylene dyads (1)
- [N]phenylenes (1)
- absorbtion fine-structure (1)
- acceptors (1)
- acid (1)
- acids (1)
- acinar-cells (1)
- acrylic acid esters (1)
- actinide, organic ligand, sorption, cementitious material, concrete, luminescence (1)
- activated carbon (1)
- activated urethane derivatives (1)
- adamantane (1)
- adduct formation (1)
- adenoassociated virus (1)
- air-water-interface (1)
- alignment (1)
- alkynol cycloisomerization (1)
- amorphous carbon (1)
- amorphous polymers (1)
- anchor peptides (1)
- anionic polymerizations (1)
- anti-fouling materials (1)
- antibodies (1)
- antifouling (1)
- antimalarial activity (1)
- aptamers (1)
- aqueous dispersion (1)
- arenediazonium salts (1)
- arsenious acid (1)
- artificial muscles (1)
- arylboronic acids (1)
- aryldiazonium salts (1)
- aspect-ratio (1)
- associating polymers (1)
- atomic force microscopy (1)
- atropisomerism (1)
- attachment (1)
- augmented-wave method (1)
- auxiliary control (1)
- beer (1)
- behavior (1)
- betaine (1)
- binding (1)
- bioanalysis (1)
- biomaterial (1)
- biophotonics (1)
- biorefineries (1)
- bladder-cancer (1)
- block-copolymer (1)
- block-copolymers (1)
- bone tissue engineering (1)
- boronic acid (1)
- brownian-motion (1)
- brushite (1)
- building-blocks (1)
- cadmium-free (1)
- calcium carbonate (1)
- calcium influx (1)
- calcium phosphate hybrid material (1)
- capacity (1)
- carbohydrate derivatives (1)
- carbohydrate esters (1)
- carbohydrate-based oxepines (1)
- carbohydrate‐ based (1)
- carbon dots (1)
- carbonyl-compounds (1)
- carboxyanhydrides (1)
- carcinogen exposure (1)
- catalysts (1)
- catalyzed cross metathesis (1)
- catalyzed redox isomerization (1)
- cationic surfactants (1)
- cell-death (1)
- cement admixtures (1)
- cement hydration (1)
- cementitious material (1)
- chain azobenzene polymers (1)
- chemical-synthesis (1)
- chemoradiation therapy (1)
- chirality (1)
- chromoionophore (1)
- citric acid (1)
- click chemistry (1)
- clusters (1)
- coatings (1)
- cockroach salivary-glands (1)
- coloring agents (1)
- complex (1)
- complexes (1)
- concrete (1)
- configuration (1)
- confocal raman microscopy (1)
- conformation (1)
- conformational-changes (1)
- construction (1)
- continuous-flow (1)
- contrast agents (1)
- controlled-release (1)
- coordination polymer (1)
- copper (1)
- copper complex (1)
- copper(II) (1)
- copper(II) halide salts (1)
- copper-bearing minerals (1)
- covalent organic framework (1)
- critical solution temperature (1)
- crosslinking (1)
- crown compounds (1)
- cryogel (1)
- crystals (1)
- cytoplasm (1)
- cytosine methylation (1)
- damage (1)
- data-storage (1)
- de-novo synthesis (1)
- decay dynamics (1)
- degradation (1)
- delivery (1)
- density functional theory (1)
- diels-alder reaction (1)
- diimine-complexes (1)
- dilute aqueous-solutions (1)
- dimerization of 4-nitrothiophenol (1)
- dip-coating (1)
- discotics (1)
- disordered media (1)
- dissociative electron attachment (1)
- dna coiling (1)
- drug delivery system (1)
- drugs (1)
- dye (1)
- dye adsorption (1)
- dye mixture (1)
- dyes (1)
- dynamic HPLC (1)
- dynamic NMR (1)
- efficient (1)
- electrochemistry (1)
- electrolytes (1)
- electron paramagnetic resonance (1)
- electron-spin resonance (1)
- electron-transfer (1)
- elemental composition (1)
- enantioselectivity (1)
- endosomal escape (1)
- energy storage (1)
- enthalpy-entropy compensation (EEC) (1)
- enzymatic degradation (1)
- enzymatic esterification (1)
- enzyme (1)
- enzyme reactions (1)
- epsilon-caprolactone (1)
- erosion (1)
- escence correlation spectroscopy (1)
- escherichia-coli (1)
- ether methacrylates (1)
- europium (1)
- exchange (1)
- excision-repair (1)
- excitation (1)
- excluded volume (1)
- exposure (1)
- extraction (1)
- fiber Bragg gratings (1)
- fiber actuators (1)
- fiber etching (1)
- fiber-optical sensors (1)
- fine-structure (1)
- fish (1)
- flexibility (1)
- flight search patterns (1)
- fluctuation-dissipation theorem (1)
- fluorescence immunoassay (1)
- fluorescence lifetime (1)
- fluorescence photobleaching recovery (1)
- fluorescence quenching (1)
- fluorescent dyemonomers (1)
- fluorescent dyes (1)
- fluorescent probes (1)
- fluorocarbon polymers (1)
- fluoroimmunoassay (1)
- foam analysis (1)
- folding kinetics (1)
- fourier-transform spectroscopy (1)
- fractional dynamics (1)
- fractional dynamics approach (1)
- frameworks (1)
- fronts (1)
- fulgides (1)
- g-quadruplex (1)
- gas (1)
- gas-phase (1)
- gases (1)
- gaussian processes (1)
- gelatin (1)
- gene-expression (1)
- gene-regulation kinetics (1)
- genomic dna methylation (1)
- gepulster DPSS Laser (1)
- germacrane sesquiterpene lactone (1)
- glass-transition temperature (1)
- glucose oxidation (1)
- gold nanoparticle assembly (1)
- gold nanoparticles (1)
- graphene (1)
- graphite (1)
- green (1)
- green chemistry (1)
- green polymers (1)
- halide-ions (1)
- hela-cells (1)
- hepcidin-25 (1)
- heterocycles (1)
- heterogeneous catalysis (1)
- holmium(III) (1)
- holographic diffraction gratings (1)
- human-cells (1)
- hydraulic oils (1)
- hydrogen (1)
- hydrogen storage (1)
- hydrogenation (1)
- hydrolysis (1)
- hydrophilic polymers (1)
- hydroxyl-functional poly(2-vinyl pyridine) (1)
- hydroyxapatite (1)
- iPLS regression (1)
- imidazolium salts (1)
- immunoassay (1)
- implementation (1)
- in-vitro (1)
- indicators (1)
- induced malignant-transformation (1)
- inhomogeneous-media (1)
- initio molecular-dynamics (1)
- inner surface (1)
- inorganic perovskites (1)
- intercomparison (1)
- intermittent chaotic systems (1)
- intracellular na+ (1)
- intramolecular charge-transfer (1)
- intrinsic microporosity (1)
- ion optodes (1)
- ionogel (1)
- ionogels (1)
- ionophore (1)
- ionothermal synthesis (1)
- isotope (1)
- isotope ratios (1)
- joziknipholones (1)
- juvenile hormone biosynthesis (1)
- labels (1)
- lanthanide luminescence (1)
- lanthanides (1)
- laser induced (1)
- laser-induced breakdown spectroscopy (1)
- lasso (1)
- levy flights (1)
- lifetime microscopy (1)
- ligand exchange (1)
- light (1)
- lignocellulosic biomass (1)
- liquid crystals (1)
- liquid-crystal precursors (1)
- liquid-phase catalysis (1)
- lower (1)
- lower critical solution temperature (1)
- lubricants (1)
- magnetic manipulation (1)
- magnetic nanoparticles (1)
- magnetic-properties (1)
- magnetite nanoparticles (1)
- marine oils (1)
- mass spectrometry (1)
- mass-spectrometry (1)
- mechanical properties (1)
- mechanical strength (1)
- mechanical-properties (1)
- membrane (1)
- membranes (1)
- mercaptocarboxylic acids (1)
- mesenchymal stem cells (1)
- metabolites (1)
- metal complex (1)
- metal nanoparticles (1)
- metal peptide (1)
- metal species (1)
- metallic nanolattices (1)
- metallopeptide (1)
- metalloprotein (1)
- methylmercury (1)
- methyltransferases dnmt3a (1)
- micelle (1)
- microbalance (1)
- microcontact printing (1)
- microgels (1)
- microporous organic polymers (1)
- microscopy (1)
- microstructure (1)
- mineralization beneath (1)
- minerals (1)
- mixed-matrix membranes (1)
- modulation (1)
- modulus (1)
- molecular dynamics (1)
- molecular oxygen (1)
- molecular rods (1)
- molecular thermometers (1)
- molecular-dynamics (1)
- molecular-mechanisms (1)
- molecular-reorientation (1)
- molecular-structure (1)
- monolayer (1)
- monomer (1)
- monomers (1)
- morphological transformation (1)
- morphology (1)
- multishell (1)
- n-heterocyclic carbenes (1)
- n-isopropylacrylamide (1)
- nanocarriers (1)
- nanoclusters (1)
- nanoflowers (1)
- nanolenses (1)
- nanoparticle dimers (1)
- nanoprisms (1)
- nanorods (1)
- nanostructure fabrication (1)
- nanotriangles (1)
- nanowires (1)
- naphthalenes (1)
- naphthalenophanes (1)
- naphthalimide (1)
- natural products (1)
- negative ions (1)
- neurodegenerative diseases (1)
- neurotoxicity (1)
- nhc (1)
- nickel (1)
- nickel(II) (1)
- nucleation (1)
- nutrients (1)
- o bond formation (1)
- o-quinone isomerase (1)
- oil (1)
- olefin-metathesis (1)
- oligo(ethylene glycol) methacrylate (1)
- oligomeric polydimethylsiloxane (1)
- optical oil sensor (1)
- optical sensing (1)
- optical-properties (1)
- optode (1)
- organic dye pigments (1)
- organic ligand (1)
- organic–inorganic hybrid (1)
- orthophosphates (1)
- oxaloacetic acid (1)
- oxidation (1)
- oxidative stress (1)
- oxygen (1)
- palladium catalyst (1)
- paper (1)
- paramagnetic-resonance (1)
- perfluorocarbon emulsion (1)
- periplaneta-americana (1)
- phase separation (1)
- phase transfer (1)
- phenanthrenes (1)
- phosgene-free synthesis (1)
- photo-dehydro-Diels-Alder reaction (1)
- photochemical synthesis (1)
- photoinduced electron transfer (1)
- photoinduced nonadiabatic dynamics (1)
- photon density wave spectroscopy (1)
- photon-counting statistics (1)
- photonic wires (1)
- photooxidation (1)
- photooxygenation (1)
- photophysics (1)
- pickering emulsion (1)
- poly(ADP-ribose) polymerase-1 (1)
- poly(N-vinylcaprolactam) (1)
- poly(dimethylsiloxane) (1)
- poly(ester amide)s (1)
- poly(ethyleneimine) (1)
- polyacrylamide (1)
- polyamine (1)
- polyammonium salt (1)
- polyampholyte (1)
- polybutadiene (1)
- polycarboxylate (1)
- polycationic monolayer (1)
- polydimethylsiloxane wrinkles (1)
- polymer amphiphile (1)
- polymer degradation (1)
- polymeric sensors (1)
- polymerization (1)
- polymersomes (1)
- polypeptide (1)
- polypeptides (1)
- polypropylene yarns (1)
- polysoap (1)
- polysulfabetaine (1)
- polysulfobetaine (1)
- polyzyklische aromatische Kohlenwasserstoffe (1)
- poly‐ ε ‐ caprolactone (1)
- porous carbon (1)
- porous carbon materials (1)
- post-polymerization modification (1)
- precatalysts (1)
- precision agriculture (1)
- pressure (1)
- process analytical technology (1)
- protein binding (1)
- protein interactions (1)
- protein-kinase inhibitors (1)
- proximal soil sensing (1)
- pulsed DPSS laser (1)
- purity (1)
- quinone (1)
- quinone methide (1)
- racemization (1)
- radicals (1)
- rare earth elements (1)
- rat (1)
- ratiometric (1)
- ray absorption-spectroscopy (1)
- reactivity (1)
- recognition (1)
- recombinant protein (1)
- redox chemistry (1)
- reference material (1)
- repair (1)
- resistive heating (1)
- resonance energy-tansfer (1)
- resonant formation (1)
- responsive polymers (1)
- responsive systems (1)
- reversible shape-memory actuator (1)
- review (1)
- ring-closing metathesis (1)
- ring-closure (1)
- roughness (1)
- rp-hplc (1)
- ruthenium carbene (1)
- samples (1)
- scale (1)
- selectivity (1)
- semiempirical methods (1)
- sensors (1)
- separation (1)
- sequence dependence (1)
- sers (1)
- shape‐memory polymer actuators (1)
- silver (1)
- silver nanowires (1)
- sinefungin (1)
- single-molecule analysis (1)
- single-strand breaks (1)
- singlet oxygen (1)
- sodium (1)
- sodium green (1)
- sodium hydroxide etching (1)
- soft robotics (1)
- soil gas (1)
- soil nutrients (1)
- solubility (1)
- solubilization (1)
- solvatochromic fluorophore (1)
- solvatochromism (1)
- solvent (1)
- spacer (1)
- spatial-organization (1)
- speciation (1)
- spectra (1)
- spectroscopy (1)
- spent coffee (1)
- spherical polyelectrolyte brushes (1)
- spider silk (1)
- spiked and crumble gold nanotriangles (1)
- square planar (1)
- stability (1)
- stannous octoate (1)
- state (1)
- states (1)
- step (1)
- stereoselective-synthesis (1)
- stereoselectivity (1)
- stokes shift (1)
- strand breakage (1)
- structural-characterization (1)
- substituted stilbenes (1)
- sulfobetain (1)
- sulfoxides (1)
- sulfur (1)
- supported gold (1)
- surface functionalization (1)
- surface modification (1)
- surface-plasmon resonance (1)
- surfaces (1)
- sustainability (1)
- switches (1)
- sättigbarer Absorber (1)
- tandem solar cells (1)
- tannic acid (1)
- tanning agents (1)
- temperature (1)
- temperature phase (1)
- tetrabromidocuprate(II) (1)
- tetrachlorocuprate(II) salts (1)
- thermal properties (1)
- thermo-responsive polymers (1)
- thermochemistry (1)
- thermodynamics (1)
- thermometer (1)
- thermoresponsive polymers (1)
- thimerosal (1)
- thin-films (1)
- thio-dimethylarsinic acid (1)
- tight-binding (1)
- time random-walks (1)
- to-coil transition (1)
- trafficking (1)
- trans-stilbenes (1)
- transformation (1)
- transition (1)
- transition-metal-complexes (1)
- triangular-[4] phenylene (1)
- trivalent (1)
- tunable diode laser (TDL) (1)
- tyrosinase; o-quinones (1)
- ultra-fast laser inscription (1)
- ultrafast (1)
- undulated (1)
- uranium (VI) (1)
- ventricular myocytes (1)
- vesicles (1)
- viologen (1)
- vitro toxicological characterization (1)
- water-soluble polymers (1)
- wavelength (1)
- weak ergodicity breaking (1)
- wettability (1)
- wrinkled stamps (1)
- zeolitic imidazolate frameworks (1)
- zwitterionic group (1)
- β-Hydroxydihydrochalcone (1)
Institute
- Institut für Chemie (236) (remove)
Quantum dots (QDs) are common as luminescing markers for imaging in biological applications because their optical properties seem to be inert against their surrounding solvent. This, together with broad and strong absorption bands and intense, sharp tuneable luminescence bands, makes them interesting candidates for methods utilizing Förster Resonance Energy Transfer (FRET), e. g. for sensitive homogeneous fluoroimmunoassays (FIA). In this work we demonstrate energy transfer from Eu<SUP>3+</SUP>-trisbipyridin (Eu-TBP) donors to CdSe-ZnS-QD acceptors in solutions with and without serum. The QDs are commercially available CdSe-ZnS core-shell particles emitting at 655 nm (QD655). The FRET system was achieved by the binding of the streptavidin conjugated donors with the biotin conjugated acceptors. After excitation of Eu-TBP and as result of the energy transfer, the luminescence of the QD655 acceptors also showed lengthened decay times like the donors. The energy transfer efficiency, as calculated from the decay times of the bound and the unbound components, amounted to 37%. The Förster-radius, estimated from the absorption and emission bands, was ca. 77 Å. The effective binding ratio, which not only depends on the ratio of binding pairs but also on unspecific binding, was obtained from the donor emission dependent on the concentration. As serum promotes unspecific binding, the overall FRET efficiency of the assay was reduced. We conclude that QDs are good substitutes for acceptors in FRET if combined with slow decay donors like Europium. The investigation of the influence of the serum provides guidance towards improving binding properties of QD assays.
To determine whether Förster resonance energy transfer (FRET) measurements can provide quantitative distance information in single-molecule fluorescence experiments on polypeptides, we measured FRET efficiency distributions for donor and acceptor dyes attached to the ends of freely diffusing polyproline molecules of various lengths. The observed mean FRET efficiencies agree with those determined from ensemble lifetime measurements but differ considerably from the values expected from Förster theory, with polyproline treated as a rigid rod. At donor–acceptor distances much less than the Förster radius R0, the observed efficiencies are lower than predicted, whereas at distances comparable to and greater than R0, they are much higher. Two possible contributions to the former are incomplete orientational averaging during the donor lifetime and, because of the large size of the dyes, breakdown of the point-dipole approximation assumed in Förster theory. End-to-end distance distributions and correlation times obtained from Langevin molecular dynamics simulations suggest that the differences for the longer polyproline peptides can be explained by chain bending, which considerably shortens the donor–acceptor distances.
Absorption and fluorescence properties of 4 hydraulic oils (3 biological and 1 petroleum-based) were investigated. In-situ LIF (laser-induced fluorescence) analysis of the oils on a brown sandy loam soil was performed. With calibration, quantitative detection was achieved. Estimated limits of detection were below ca. 500 mg/kg for the petroleum-based oil and ca. 2000 mg/kg for one biological oil. A semi-quantitative classification scheme is proposed for monitoring of the biological oils. This approach was applied to investigate the migration of a biological oil in soil-containing compartments, namely a soil column and a soil bed.
Im vorliegenden Beitrag wird an Hand dreier Beispiele der Einsatz von optischer Sensorik zur Produktcharakterisierung dargestellt, nämlich Untersuchungen zum O2-Gehalt in Fruchtsäften, zur Isotopiesignatur von CO2 in Mineralwässern und zu Lichtstreueigenschaften eines Sonnenschutzmittels. Inhalt: Bestimmung von O2 mit Lumineszenzsonden Isotopenselektive Bestimmung von CO2 mit TDLAS Optische Charakterisierung stark streuender Materialien mit Photonendichtewellen
The fluorescence properties and the fluorescence quenching by Tb3+ of substituted benzoic acid were investigated in solution at different pH. The substituted benzoic acids were used as simple model compounds for chromophores present in humic substances (HS). It is shown that the fluorescence properties of the model compounds resemble fluorescence of HS quite well. A major factor determining the fluorescence of model compounds are proton transfer reactions in the electronically excited state. It is intriguing that the fluorescence of the model compounds was almost not quenched by Tb3+ while the HS fluorescence was decreased very effectively. From our results we concluded that proton transfer reactions as well as conformational reorientation processes play an important role in the fluorescence of HS. The luminescence of bound Tb3+ was sensitized by an energy transfer step upon excitation of the model compounds and of HS, respectively. For HS the observed sensitization was dependent on its origin indicating differences 1) in the connection between chromophores and binding sites and 2) in the energy levels of the chromophore triplet states. Hence, the observed sensitization of the Tb3+ luminescence could be useful to characterize structural differences of HS in solution. Interlanthanide energy transfer between Tb3+ and Nd3+ was used to determine the average distance R between both ions using the well-known formalism of luminescence resonance energy transfer. R was dependent on the origin of the HS reflecting the difference in structure. The value of Rmin seemed to be a unique feature of the HS. It was further found that upon variation of the pH R also changed. This demonstrates that the measurement of interlanthanide energy transfer can be used as a direct method to monitor conformational changes in HS.
A technique has been developed to measure absolute intracellular oxygen concentrations in green plants. Oxygen-sensitive phosphorescent microbeads were injected into the cells and an optical multifrequency phase-modulation technique was used to discriminate the sensor signal from the strong autofluorescence of the plant tissue. The method was established using photosynthesis-competent cells of the giant algae Chara corallina L., and was validated by application to various cell types of other plant species.
Pestizideinsatz gegen die Rosskastanien-Miniermotte (Cameraria ohridella) im Stadtgebiet Potsdam
(2005)
In Deutschland hat sich in den letzten zehn Jahren die aus dem Balkan eingewanderte Rosskastanien-Miniermotte verbreitet; sie richtet vor allem in Ballungsgebieten an der weiß blühenden Rosskastanie starke Schäden an. Neben der vollständigen mechanischen Beseitigung und Entsorgung des Falllaubes im Herbst eignen sich zur Bekämpfung chemische Pflanzenschutzmittel. In Potsdam sind 2001 und 2003 an zwei Standorten befallene Rosskastanien versuchsweise mit zwei unterschiedlichen Pestiziden erfolgreich behandelt worden. 2005 wurden die Standorte beprobt und die Bodenproben auf Rückstände der verwendeten Mittel untersucht. TerraTech möchte Kommunen mit vergleichbarem Problem Hinweise auf Bekämpfungsmethoden geben, veröffentlicht diesen Beitrag aber vor allem unter dem Gesichtspunkt des Boden- und Grundwasserschutzes.
Deuteration effects on the vibronic structure of the emission and excitation spectra of triangular [4]phenylene (D3h[4]phenylene) were studied using laser-excited Shpolskii spectroscopy (LESS) in an octane matrix at 4.2 K. For correct assignment of the vibrational modes, the experimental results were compared with calculated frequencies (B3LYP/6-31G*). CH vibrations were identified by their characteristic isotopic shifts in the spectra of deuterated triangular [4]phenylenes. Two CC stretching modes, at 100 cm–1 and 1176 cm–1, suitable as probes for bond strength changes in the excited state, were identified. The isotope effect on the internal conversion rates of triangular [4]phenylene was evaluated from measurements of temperature dependent lifetime. Isotope dependency and the magnitude of the internal conversion rates indicate that internal conversion in triangular [4]phenylene is most likely induced by CH vibrations. The results obtained by LESS and lifetime measurements were compared with PM3 PECI calculations of the excited state structure. The theoretical results and the relation between ground and excited state vibration energies of the 1176 cm–1 probe vibration indicate a reduction of bond alternation of the central cyclohexatriene ring in the excited state.
The drift time spectra of polycyclic aromatic hydrocarbons (PAH), alkylbenzenes and alkylphenylethers were recorded with a laser-based ion mobility (IM) spectrometer. The ion mobilities of all compounds were determined in helium as drift gas. This allows the calculation of the diffusion cross sections (Omegacalc) on the basis of the exact hard sphere scattering model (EHSSM) and their comparison with the experimentally determined diffusion cross sections (Omegaexp). These Omegaexp/Omegacalc-correlations are presented for molecules with a rigid structure like PAH and prove the reliability of the theoretical model and experimental method. The increase of the selectivity of IM spectrometry is demonstrated using resonance enhanced multiphoton ionisation (REMPI) at atmospheric pressure, realized by tuneable lasers. The REMPI spectra of nine alkylbenzenes and alkylphenylethers are investigated. On the basis of these spectra, the complete qualitative distinction of eight compounds in a mixture is shown. These experiments are extended to alkylbenzene isomer mixtures.
The performance of a home-built tunable diode laser (TDL) spectrometer has been optimized regarding multi-line detection of carbon dioxide in natural gases. In the regime of the (30<SUP>0</SUP>1)<SUB>III</SUB> ← (000) band of <SUP>12</SUP>CO<SUB>2</SUB> around 1.6 μm, the dominating isotope species <SUP>12</SUP>CO<SUB>2</SUB>, <SUP>13</SUP>CO<SUB>2</SUB>, and <SUP>12</SUP>C<SUP>18</SUP>O<SUP>16</SUP>O were detected simultaneously. In contrast to most established techniques, selective measurements are performed without any sample preparation. This is possible since the CO<SUB>2</SUB> detection is free of interference from water, ubiquitous in natural gases. Detection limits in the range of a few ppmv were obtained for each species utilizing wavelength modulation (WM) spectroscopy with balanced detection in a long-path absorption cell set-up. Linear calibration plots cover a dynamic range of four orders of magnitude, allowing for quantitative CO<SUB>2</SUB> detection in various samples, like soil and breath gas. High isotopic resolution enables the excellent selectivity, sensitivity, and stability of the chosen analytical concept. The obtained isotopic resolution of typically ± 1.0 ‰ and ± 1.5 ‰ (for 3 vol. % and 0.7 vol. % of CO<SUB>2</SUB>, respectively) offers a promising analytical tool for isotope-ratio determination of carbon dioxide in soil gas. Preliminary experiments on soil respiration for the first time combine the on-line quantification of the overall carbon dioxide content with an optode sensor and isotopic determination (TDL system) of natural gas species.