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 - 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 - 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 - 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 - JOUR
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
Y1 - 2002
ER -
TY - JOUR
A1 - Löhmannsröben, Hans-Gerd
A1 - Lemke, Matthias
A1 - Schober, Lars
A1 - Schultze, Rainer
T1 - In-situ Analytik von organischen Bodenkontaminationen mit Laser-induzierter Fluoreszenz
Y1 - 2000
ER -
TY - JOUR
A1 - Löhmannsröben, Hans-Gerd
A1 - Theo, Hengstermann
A1 - Lemke, Matthias
A1 - Schober, Lars
A1 - Schultze, Rainer
T1 - Entwicklung eines optischen Meßsystems zur in-situ Bestimmung von Fluoreszenztracern, Sauerstoff und pH- Wert in Gewässern (FLUTRAS: Fluorescence Tracer Detection System)
Y1 - 2000
ER -
TY - JOUR
A1 - Schober, Lars
A1 - Löhmannsröben, Hans-Gerd
T1 - Determination of optical parameters for light penetration in particulate materials and soils with diffuse reflectance (DR) spectroscopy
Y1 - 2000
ER -
TY - JOUR
A1 - Löhmannsröben, Hans-Gerd
T1 - In situ Laser-induced fluorescence (LIF) analysis pf petroleum product-contaminared soil samples
Y1 - 2000
ER -
TY - JOUR
A1 - Haitzer, Markus
A1 - Löhmannsröben, Hans-Gerd
A1 - Steinberg, Christian E. W.
A1 - Zimmermann, Ute
T1 - In vivo laser-induced fluorescence detection of pyrene in nematodes and determination of pyrene binding constants for humic substances by fluorescences quenching and bioaccumulation experiments
Y1 - 2000
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 - 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 - JOUR
A1 - Schael, Frank
A1 - Reich, Oliver
A1 - Löhmannsröben, Hans-Gerd
T1 - Near infrared diode laser spectroscopy of organic compounds in turbid aqueous solutions
N2 - Diffuse reflectance measurements and photon migration studies with near infrared (NIR) diode lasers were employed to elucidate experimental methods for determining absorption and scattering coefficients and species concentrations in highly scattering solutions. Applicability of theoretical approaches were established by investigating model systems with absorbing (e.g. ink, malachite green) and scattering (e.g. milk powder, caolinit) species in aqueous solution. While diffuse reflectance measurements practically requires calibration procedures, photon migration studies allow quantitative determination of absorption and scattering coefficients of turbid solutions consistent with absorptions coefficients obtained from Lambert-Beer's law. Furthermore, NIR absorption spectra of water, chlorinated hydrocarbons (chloroform, 1,2-dichloroethane, trichloroethene) and of various sugars ($alpha$-D-glucose, sucrose, maltose) are discussed. Spectral variations of NIR water absorption with temperature and solvents are exammined. Exemplary, NIR diode laser detection of water in acetone/water mixtures is performed.
Y1 - 2000
SN - 0-9528666-1-7
ER -
TY - JOUR
A1 - Löhmannsröben, Hans-Gerd
A1 - Schael, Frank
A1 - Reich, Oliver
A1 - Lemke, Matthias
A1 - Schober, Lars
T1 - Untersuchung von organischer Bodensubstanz und Bodengasen mit laser-spektroskopischer in-situ Meßtechnik
Y1 - 2000
ER -