TY - CHAP
A1 - Asche, Hartmut
A1 - Böckmann, Christine
A1 - Laue, Steffen
A1 - Löhmannsröben, Hans-Gerd
A1 - Lemke, Matthias
A1 - Schober, Lars
A1 - Reich, Oliver
A1 - Lück, Erika
A1 - Schütte, Marc
A1 - Domsch, Horst
A1 - Makower, Alexander
A1 - Scheller, Frieder W.
A1 - Stöcklein, Wolfgang
A1 - Wollenberger, Ursula
A1 - Schultze, Rainer
A1 - Hengstermann, Theo
A1 - Schael, Frank
T1 - Umweltforschung für das Land Brandenburg : Projekt Umweltanalytik / Umweltmeßtechnik / Informationssysteme
Y1 - 2000
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-3862
SP - 176
EP - 227
ER -
TY - CHAP
A1 - Lück, Erika
A1 - Balderjahn, Ingo
A1 - Kamm, Birgit
A1 - Greil, Holle
A1 - Wallschläger, Hans-Dieter
A1 - Jessel, Beate
A1 - Böckmann, Christine
A1 - Oberhänsli, Roland
A1 - Soyez, Konrad
A1 - Schmeer, Ernst
A1 - Blumenstein, Oswald
A1 - Berndt, Klaus-Peter
A1 - Edeling, Thomas
A1 - Friedrich, Sabine
A1 - Kaden, Klaus
A1 - Scheller, Frieder W.
A1 - Petersen, Hans-Georg
A1 - Asche, Hartmut
A1 - Bronstert, Axel
A1 - Giest, Hartmut
A1 - Gaedke, Ursula
A1 - Löhmannsröben, Hans-Gerd
A1 - Jeltsch, Florian
A1 - Jänkel, Ralph
A1 - Gzik, Axel
A1 - Bork, Hans-Rudolf
A1 - Bork, Hans-Rudolf
T1 - Umweltforschung für das Land Brandenburg : Arbeitsgruppen und Professuren
Y1 - 2000
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-3797
ER -
TY - GEN
A1 - Erler, Alexander
A1 - Riebe, Daniel
A1 - Beitz, Toralf
A1 - Löhmannsröben, Hans-Gerd
A1 - Gebbers, Robin
T1 - Soil Nutrient Detection for Precision Agriculture Using Handheld Laser-Induced Breakdown Spectroscopy (LIBS) and Multivariate Regression Methods (PLSR, Lasso and GPR)
T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2 - Precision agriculture (PA) strongly relies on spatially differentiated sensor information. Handheld instruments based on laser-induced breakdown spectroscopy (LIBS) are a promising sensor technique for the in-field determination of various soil parameters. In this work, the potential of handheld LIBS for the determination of the total mass fractions of the major nutrients Ca, K, Mg, N, P and the trace nutrients Mn, Fe was evaluated. Additionally, other soil parameters, such as humus content, soil pH value and plant available P content, were determined. Since the quantification of nutrients by LIBS depends strongly on the soil matrix, various multivariate regression methods were used for calibration and prediction. These include partial least squares regression (PLSR), least absolute shrinkage and selection operator regression (Lasso), and Gaussian process regression (GPR). The best prediction results were obtained for Ca, K, Mg and Fe. The coefficients of determination obtained for other nutrients were smaller. This is due to much lower concentrations in the case of Mn, while the low number of lines and very weak intensities are the reason for the deviation of N and P. Soil parameters that are not directly related to one element, such as pH, could also be predicted. Lasso and GPR yielded slightly better results than PLSR. Additionally, several methods of data pretreatment were investigated.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 815
KW - LIBS
KW - lasso
KW - PLS regression
KW - gaussian processes
KW - soil
KW - precision agriculture
KW - nutrients
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-444183
SN - 1866-8372
IS - 815
ER -
TY - GEN
A1 - Hildebrandt, Nico
A1 - Charbonnière, Loïc J.
A1 - Ziessel, Raymond F.
A1 - Löhmannsröben, Hans-Gerd
T1 - Quantum dots as resonance energy transfer acceptors for monitoring biological interactions
N2 - 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 Forster Resonance Energy Transfer (FRET), e. g. for sensitive homogeneous fluoroimmunoassays (FIA). In this work we demonstrate energy transfer from Eu3+-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 Forster-radius, estimated from the absorption and emission bands, was ca. 77Å. 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.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 012
Y1 - 2006
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-12213
ER -
TY - GEN
A1 - Beck, Michael
A1 - Hildebrandt, Niko
A1 - Löhmannsröben, Hans-Gerd
T1 - Quantum dots as acceptors in FRET-assays containing serum
N2 - 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 Eu3+-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.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 019
KW - Quantenpunkt
KW - Lumineszenz
KW - Serum
KW - Europium
KW - Immunoassay
KW - Energietransfer
KW - Fluoreszenz-Resonanz-Energie-Transfer
KW - Förster-Resonanz-Energie-Transfer
KW - Quantum Dot
KW - Luminescence
KW - Serum
KW - Europium
KW - Immunoassay
KW - Energy Transfer
KW - FRET
Y1 - 2006
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-9504
ER -
TY - GEN
A1 - Dosche, Carsten
A1 - Löhmannsröben, Hans-Gerd
A1 - Bieser, A.
A1 - Dosa, P. I.
A1 - Han, S.
A1 - Iwamoto, M.
A1 - Schleifenbaum, A.
A1 - Vollhardt, K. Peter C.
T1 - Photophysical properties of [N]phenylenes
N2 - In the present study, photophysical properties of [N]phenylenes were studied by means of stationary and time-resolved absorption and fluorescence spectroscopy (in THF at room temperature). For biphenylene (1) and linear [3]phenylene (2a), internal conversion (IC) with quantum yields ΦIC > 0.99 is by far the dominant mechanism of S1 state deactivation. Angular [3]phenylene (3a), the zig-zag [4]- and [5]phenylenes (3b), (3c), and the triangular [4]phenylene (4) show fluorescence emission with fluorescence quantum yieds and lifetimes between ΦF = 0.07 for (3a) and 0.21 for (3c) and τF = 20 ns for (3a) and 81 ns for (4). Also, compounds (3) and (4) exhibit triplet formation upon photoexcitation with quantum yields as high as ΦISC = 0.45 for (3c). The strong differences in the fluorescence properties and in the triplet fromation efficiencies between (1) and (2a) on one hand and (3) and (4) on the other are related to the remarkable variation of the internal conversion (IC) rate constants kIC. A tentative classification of (1) and (2a) as “fast IC compounds”, with kIC > 109 s-1, and of (3) and (4) as “slow IC compounds”, with kIC ≈ 107 s-1, is suggested. This classification cannot simply be related to Hückel’s rule-type concepts of aromaticity, because the group of “fast IC compounds” consists of “antiaromatic” (1) and “aromatic” (2a), and the group of “slow IC compounds” consists of “antiaromatic” (3b), (4) and “aromatic” (3a), (3c). The IC in the [N]phenylenes is discussed within the framework of the so-called energy gap law established for non-radiative processes in benzenoid hydrocarbons.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 001
Y1 - 2002
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-11936
ER -
TY - GEN
A1 - Cywiński, Piotr J.
A1 - Nono, Katia Nchimi
A1 - Charbonnière, Loïc J.
A1 - Hammann, Tommy
A1 - Löhmannsröben, Hans-Gerd
T1 - Photophysical evaluation of a new functional terbium complex in FRET-based time-resolved homogenous fluoroassays
N2 - A new functional luminescent lanthanide complex (LLC) has been synthesized with terbium as a central lanthanide ion and biotin as a functional moiety. Unlike in typical lanthanide complexes assembled via carboxylic moieties, in the presented complex, four phosphate groups are chelating the central lanthanide ion. This special chemical assembly enhances the complex stability in phosphate buffers conventionally used in biochemistry. The complex synthesis strategy and photophysical properties are described as well as the performance in time-resolved Förster Resonance Energy Transfer (FRET) assays. In those assays, this biotin-LLC transferred energy either to acceptor organic dyes (Cy5 or AF680) labelled on streptavidin or to quantum dots (QD655 or QD705) surface-functionalised with streptavidins. The permanent spatial donor–acceptor proximity is assured through strong and stable biotin–streptavidin binding. The energy transfer is evidenced from the quenching observed in donor emission and from a decrease in donor luminescence decay, both associated with simultaneous increase in acceptor intensity and in the decay time. The dye-based assays are realised in TRIS and in PBS, whereas QD-based systems are studied in borate buffer. The delayed emission analysis allows for quantifying the recognition process and for auto-fluorescence-free detection, which is particularly relevant for application in bioanalysis. In accordance with Förster theory, Förster-radii (R0) were found to be around 60 Å for organic dyes and around 105 Å for QDs. The FRET efficiency (η) reached 80% and 25% for dye and QD acceptors, respectively. Physical donor–acceptor distances (r) have been determined in the range 45–60 Å for organic dye acceptors, while for acceptor QDs between 120 Å and 145 Å. This newly synthesised biotin-LLC extends the class of highly sensitive analytical tools to be applied in the bioanalytical methods such as time-resolved fluoroimmunoassays (TR-FIA), luminescent imaging and biosensing.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 252
KW - acceptors
KW - bioanalysis
KW - contrast agents
KW - europium
KW - fluoroimmunoassay
KW - labels
KW - lanthanide luminescence
KW - quantum dots
KW - resonance energy-transfer
Y1 - 2014
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-95390
SP - 6060
EP - 6067
ER -
TY - GEN
A1 - Dosche, Carsten
A1 - Mickler, Wulfhard
A1 - Löhmannsröben, Hans-Gerd
A1 - Agenet, Nicolas
A1 - Vollhardt, K. Peter C.
T1 - Photoinduced electron transfer in [N]phenylenes
N2 - First studies of electron transfer in [N]phenylenes were performed in bimolecular quenching reactions of angular [3]- and triangular [4]phenylene with various electron acceptors. The relation between the quenching rate constants kq and the free energy change of the electron transfer (ΔG0CS ) could be described by the Rehm-Weller equation. From the experimental results, a reorganization energy λ of 0.7 eV was derived. Intramolecular electron transfer reactions were studied in an [N]phenylene bichomophore and a corresponding reference compound. Fluorescence lifetime and quantum yield of the bichromophor display a characteristic dependence on the solvent polarity, whereas the corresponding values of the reference compound remain constant. From the results, a nearly isoenergonic ΔG0CS can be determined. As the triplet quantum yield is nearly independent of the polarity, charge recombination leads to the population of the triplet state.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 23
KW - [N]phenylenes
KW - photoinduced electron transfer
KW - [N]phenylene dyads
Y1 - 2007
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-12463
ER -
TY - GEN
A1 - Zühlke, Martin
A1 - Meiling, Till Thomas
A1 - Roder, Phillip
A1 - Riebe, Daniel
A1 - Beitz, Toralf
A1 - Bald, Ilko
A1 - Löhmannsröben, Hans-Gerd
A1 - Janßen, Traute
A1 - Erhard, Marcel
A1 - Repp, Alexander
T1 - Photodynamic Inactivation of E. coli Bacteria via Carbon Nanodots
T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2 - The increasing development of antibiotic resistance in bacteria has been a major problem for years, both in human and veterinary medicine. Prophylactic measures, such as the use of vaccines, are of great importance in reducing the use of antibiotics in livestock. These vaccines are mainly produced based on formaldehyde inactivation. However, the latter damages the recognition elements of the bacterial proteins and thus could reduce the immune response in the animal. An alternative inactivation method developed in this work is based on gentle photodynamic inactivation using carbon nanodots (CNDs) at excitation wavelengths λex > 290 nm. The photodynamic inactivation was characterized on the nonvirulent laboratory strain Escherichia coli K12 using synthesized CNDs. For a gentle inactivation, the CNDs must be absorbed into the cytoplasm of the E. coli cell. Thus, the inactivation through photoinduced formation of reactive oxygen species only takes place inside the bacterium, which means that the outer membrane is neither damaged nor altered. The loading of the CNDs into E. coli was examined using fluorescence microscopy. Complete loading of the bacterial cells could be achieved in less than 10 min. These studies revealed a reversible uptake process allowing the recovery and reuse of the CNDs after irradiation and before the administration of the vaccine. The success of photodynamic inactivation was verified by viability assays on agar. In a homemade flow photoreactor, the fastest successful irradiation of the bacteria could be carried out in 34 s. Therefore, the photodynamic inactivation based on CNDs is very effective. The membrane integrity of the bacteria after irradiation was verified by slide agglutination and atomic force microscopy. The method developed for the laboratory strain E. coli K12 could then be successfully applied to the important avian pathogens Bordetella avium and Ornithobacterium rhinotracheale to aid the development of novel vaccines.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1220
KW - Bacteria
KW - Genetics
KW - Fluorescence
KW - Photodynamics
KW - Irradiation
Y1 - 2022
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-538425
SN - 1866-8372
SP - 23742
EP - 23749
PB - Universität Potsdam
CY - Potsdam
ER -
TY - GEN
A1 - Reich, Oliver
A1 - Löhmannsröben, Hans-Gerd
A1 - Schael, Frank
T1 - Optical sensing with photon density waves: investigation of model media
N2 - Investigations with frequency domain photon density waves allow elucidation of absorption and scattering properties of turbid media. The temporal and spatial propagation of intensity modulated light with frequencies up to more than 1 GHz can be described by the P1 approximation to the Boltzmann transport equation. In this study, we establish requirements for the appropriate choice of turbid model media and characterize mixtures of isosulfan blue as absorber and polystyrene beads as scatterer. For these model media, the independent determination of absorption and reduced scattering coefficients over large absorber and scatterer concentration ranges is demonstrated with a frequency domain photon density wave spectrometer employing intensity and phase measurements at various modulation frequencies.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 026
Y1 - 2003
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-13147
ER -
TY - GEN
A1 - Löhmannsröben, Hans-Gerd
A1 - Kantor, Zoltan
A1 - Kumke, Michael Uwe
A1 - Schmälzlin, Elmar
A1 - Reich, Oliver
T1 - OPQS – optische Prozess- und Qualitäts-Sensorik
N2 - 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
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 028
KW - Sensorik
KW - Prozesskontrolle
KW - Absorption
KW - Lumineszenz
KW - Lichtstreuung
KW - Isotopie
Y1 - 2005
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-13205
ER -
TY - GEN
A1 - Engelhard, Sonja
A1 - Kumke, Michael Uwe
A1 - Löhmannsröben, Hans-Gerd
T1 - OPQS – optical process and quality sensing : exemplary applications in the beerbrewing and polyurethane foaming processes
N2 - Optical methods play an important role in process analytical technologies (PAT). Four examples of optical process and quality sensing (OPQS) are presented, which are based on three important experimental techniques: near-infrared absorption, luminescence quenching, and a novel method, photon density wave (PDW) spectroscopy. These are used to evaluate four process and quality parameters related to beer brewing and polyurethane (PU) foaming processes: the ethanol content and the oxygen (O2) content in beer, the biomass in a bioreactor, and the cellular structures of PU foam produced in a pilot production plant.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 004
KW - process analytical technology
KW - beer
KW - biomass
KW - foam analysis
KW - NIR spectroscopy
KW - fluorescence quenching
KW - photon density wave spectroscopy
Y1 - 2006
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-12191
ER -
TY - GEN
A1 - Hörner, Gerald
A1 - Lau, Steffen
A1 - Löhmannsröben, Hans-Gerd
T1 - NIR-diode laser spectroscopy for isotope-selective sensing of soil-respired carbon dioxide
N2 - 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 (3001)III ← (000) band of 12CO2 around 1.6 μm, the dominating isotope species 12CO2, 13CO2, and 12C18O16O were detected simultaneously. In contrast to most established techniques, selective measurements are performed without any sample preparation. This is possible since the CO2 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 CO2 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 CO2, 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.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 021
KW - Kohlendioxid
KW - Isotopenverhältnis
KW - Bodengas
KW - Diodenlaserspektroskopie
KW - tunable diode laser (TDL)
KW - carbon dioxide
KW - isotope ratios
KW - soil gas
Y1 - 2004
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-10148
ER -
TY - GEN
A1 - Löhmannsröben, Hans-Gerd
A1 - Beck, Michael
A1 - Hildebrandt, Niko
A1 - Schmälzlin, Elmar
A1 - van Dongen, Joost T.
T1 - New challenges in biophotonics : laser-based fluoroimmuno analysis and in-vivo optical oxygen monitoring
N2 - Two examples of our biophotonic research utilizing nanoparticles are presented, namely laser-based fluoroimmuno analysis and in-vivo optical oxygen monitoring. Results of the work include significantly enhanced sensitivity of a homogeneous fluorescence immunoassay and markedly improved spatial resolution of oxygen gradients in root nodules of a legume species.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 018
KW - Sauerstoff
KW - Quantenpunkt
KW - Lumineszenz
KW - Immunoassay
KW - Energietransfer
KW - Fluoreszenz-Resonanz-Energie-Transfer
KW - Nanopartikel
KW - Lanthanoide
KW - Optode
KW - Förster Resonanz Energie Transfer
KW - Biophotonik
KW - biophotonics
KW - nanoparticles
KW - immunoassay
KW - oxygen
KW - optode
Y1 - 2006
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-10120
ER -
TY - GEN
A1 - Schmälzlin, Elmar
A1 - Walz, Bernd
A1 - Klimant, Ingo
A1 - Schewe, Bettina
A1 - Löhmannsröben, Hans-Gerd
T1 - Monitoring hormone-induced oxygen consumption in the salivary glands of the blowfly, Calliphora vicina, by use of luminescent microbeads
N2 - The salivary glands of the blowfly were injected with luminescent oxygen-sensitive microbeads. The changes in oxygen content within individual gland tubules during hormone-induced secretory activity were quantified. The measurements are based on an upgraded phase-modulation technique, where the phase shift of the sensor phosphorescence is determined independently from concentration and background signals. We show that the combination of a lock-in amplifier with a fluorescence microscope results in a convenient setup to measure oxygen concentrations within living animal tissues at the cellular level.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 006
Y1 - 2006
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-12206
ER -
TY - GEN
A1 - Schultze, Rainer H.
A1 - Lemke, Matthias
A1 - Löhmannsröben, Hans-Gerd
T1 - Laser-induced fluorescence (LIF) spectroscopy for the in situ analysis of petroleum product-contaminated soils
N2 - Contents: Introduction Experimental Techniques: The LIF demonstrator unit - The LIF demonstrator unit - The mobile LIF spectrometer OPTIMOS - Investigated petroleum products and soil samples Results and Discussion: Photophysical properties of the petroleum products LIF spectroscopic investigations of oil-spiked samples LIF spectroscopic investigations of real-world soils Conclusions
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 9
Y1 - 2004
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-12271
ER -
TY - GEN
A1 - Löhmannsröben, Hans-Gerd
A1 - Beitz, Toralf
A1 - Luadien, Robert
A1 - Schultze, Rainer
T1 - Laser-based ion mobility spectrometry for sensing of aromatic compounds
N2 - 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.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 003
KW - Laser
KW - REMPI
KW - Ion mobility spectrometry
KW - PAH
Y1 - 2004
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-11892
ER -
TY - GEN
A1 - Lau, Steffen
A1 - Salffner, Katharina
A1 - Löhmannsröben, Hans-Gerd
T1 - Isotopic resolution of carbon monoxide and carbon dioxide by NIR diode laser spectroscopy
N2 - Near-infrared (NIR) absorption spectroscopy with tunable diode lasers allows the simultaneous detection of the three most important isotopologues of carbon dioxide (12CO2, 13CO2, 12C18O16O) and carbon monoxide (12CO, 13CO, 12C18O). The flexible and compact fiber-optic tunable diode laser absorption spectrometer (TDLAS) allows selective measurements of CO2 and CO with high isotopic resolution without sample preparation since there is no interference with water vapour. For each species, linear calibration plots with a dynamic range of four orders of magnitude and detection limits (LOD) in the range of a few ppm were obtained utilizing wavelength modulation spectroscopy (WMS) with balanced detection in a Herriott-type multipass cell. The high performance of the apparatus is illustrated by fill-evacuation-refill cycles.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 017
KW - Isotop
KW - Kohlenmonoxid
KW - Kohlendioxid
KW - Diodenlaserspektroskopie
KW - isotope
KW - carbon monoxide
KW - carbon dioxide
KW - diode laser spectroscopy
Y1 - 2006
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-10135
ER -
TY - GEN
A1 - Hörner, Gerald
A1 - Lau, Steffen
A1 - Kantor, Zoltan
A1 - Löhmannsröben, Hans-Gerd
T1 - Isotope selective analysis of CO2 with tunable diode laser (TDL) spectroscopy in the NIR
N2 - The performance of a home-built tunable diode laser (TDL) spectrometer, aimed at multi-line detection of carbon dioxide, has been evaluated and optimized. In the regime of the (3001)III / (000) band of 12CO2 around 1.6 μm, the dominating isotope species 12CO2, 13CO2, and 12C18O16O were detected simultaneously without interference by water vapor. Detection limits in the range of few ppmv were obtained for each species utilizing wavelength modulation (WM) spectroscopy with balanced detection in a long-path absorption cell set-up. High sensitivity in conjunction with high precision —typically ±1‰ and ±6‰ for 3% and 0.7% of CO2, respectively— renders this experimental approach a promising analytical concept for isotope-ratio determination of carbon dioxide in soil and breath gas. For a moderate 12CO2 line, the pressure dependence of the line profile was characterized in detail, to account for pressure effects on sensitive measurements.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 020
KW - Isotopenverhältnis
KW - Kohlendioxid
KW - Diodenlaserspektroskopie
KW - Isotope ratio
KW - carbon monoxide
KW - diode laser spectroscopy
Y1 - 2004
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-10167
ER -
TY - GEN
A1 - Lemke, Matthias
A1 - Fernández-Trujillo, Rebeca
A1 - Löhmannsröben, Hans-Gerd
T1 - In-situ LIF analysis of biological and petroleum-based hydraulic oils on soil
N2 - 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.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 011
KW - in-situ
KW - optical oil sensor
KW - lubricants
KW - hydraulic oils
KW - soil
KW - laser induced
Y1 - 2005
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-12268
ER -