TY - THES A1 - Marmodée, Bettina T1 - Fluorenscence Line-Narrowing-Spektroskopie zur Charakterisierung von Eu(III) in Komplexen mit kleinen organischen Liganden Y1 - 2012 CY - Potsdam ER - TY - JOUR A1 - Marmodée, Bettina A1 - de Klerk, Joost A1 - Ariese, Freek A1 - Gooijer, Cees A1 - Kumke, Michael Uwe T1 - Metal binding by humic substances : characterization by high-resolution-lanthanide-ion-probe-spectroscopy (HR- LIPS) N2 - In ultra-low-temperature experiments at 4.7 K the luminescence of Eu(III) bound to different hydroxy- and methoxybenzoic acids and to humic substances (HS) was investigated. The benzoic acid derivatives were used as simple model compounds for common metal-binding structures in HS. The Eu(III) luminescence was directly excited by means of a pulsed dye laser, scanning through the D-5(0) -> F-7(0) transition of Eu(III) and subsequently, high-resolution total luminescence spectra (TLS) were recorded. Based on the thorough analysis of the high-resolution TLS conclusions were drawn with respect to the number of different complexes formed and to the symmetry of the complexes. The crystal-field strength parameter N-nu(B-2q) was dependent on the electrostatic forces induced by the ligands as well as on the symmetry of the complexes. The formation of thermodynamically stable complexes was found to be slow even for small model ligands such its 2-hydroxybenzoic acid. Comparison between the model compounds and HS clearly revealed that the carboxylate group is the dominant binding site in HS. Indices for the formation of chelates, e.g. similar to 2- hydroxybenzoic acid, were not found for HS. Y1 - 2009 UR - http://www.znaturforsch.com/a.htm SN - 0932-0784 ER - TY - JOUR A1 - Marmodée, Bettina A1 - de Klerk, Joost S. A1 - Ariese, Freek A1 - Gooijer, Cees A1 - Kumke, Michael Uwe T1 - High-resolution steady-state and time-resolved luminescence studies on the complexes of Eu(III) with aromatic or aliphatic carboxylic acids N2 - Eu(III) luminescence spectroscopy, both in the steady-state and the time-resolved mode, is an appropriate technique to study the properties of complexes between heavy metal ions and humic substances (HS), which play a key role in the distribution of metal species in the environment. Unfortunately, room temperature luminescence spectra of Eu(III) complexes with aromatic and aliphatic carboxylic acids - model compounds of HS binding sites - are too broad to fully exploit their potential analytical information content. It is shown that under cryogenic conditions fluorescence-line- narrowing (FLN) is achieved, and the highly resolved spectra provide detailed information on the complexes. Ten model ligands were investigated. Total luminescence spectra (TLS) were recorded, using the D-5(0) -> F-7(0) transition for excitation and the D-5(0) -> F-7(1) and D-5(0) -> F-7(2) transitions for emission. The energy of the excitation transition depends on the ligand involved and the structure and composition of the complex. For most ligands, discontinuities in the high-resolution TLS indicated that more species, i.e. distinct complex structures, coexisted in the sample. Selective excitation was performed to measure the species-associated luminescence decay times tau. The latter strongly depend on nearby OH oscillators from coordinating water molecules or ligand hydroxyl groups. Furthermore, the asymmetry ratios r, defined as the intensity ratio of the D-5(0) -> F-7(2) and D-5(0) -> F-7(1) transitions, were calculated and the variation of the excitation energy E-exc with the splitting of the F-7(1) triplet (Delta E) was determined. which yielded the crystal field strength parameter N-nu(B-2q), as well as the crystal field parameters B-20 and B-22. An in-depth analysis of the results is presented, providing detailed information on the number of coexisting complexes, their stoichiometry, the number of water molecules in the first coordination sphere and their geometry (symmetry point group). Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/00032670 U6 - https://doi.org/10.1016/j.aca.2009.06.006 SN - 0003-2670 ER - TY - JOUR A1 - Marmodée, Bettina A1 - Klerk de, Joost A1 - Kumke, Michael Uwe A1 - Ariese, Freek A1 - Gooijer, Cees T1 - Spectroscopic investigations of complexes between Eu(III) and aromatic carboxylic ligands N2 - In order to obtain information on the number and symmetry of the different Eu3+ complexes formed with several hydroxybenzoic acids, ultra-low temperature luminescence measurements at 4.7 K were carried out. Hydroxybenzoic acids were used as simple model compounds for metal binding structures in humic substances (HS). Information on the complexes was extracted from high-resolution total luminescence spectra (TLS), which were obtained by scanning through the D-5(0) <-- F-7(0) transition of Eu(III) with a pulsed dye laser and measuring the emission in the wavelength range of the D- 5(0) --> F-7(0) and D-5(0) --> F-7(0) transitions simultaneously. By extracting the crystal field strength parameter N- v(B-2q) from the TLS, it was found that N-v(B-2q) was not directly correlated with the excitation energy. Further, the symmetry of the individual complexes formed was extracted from the experimental data. (C) 2007 Elsevier B.V. All rights reserved. Y1 - 2008 U6 - https://doi.org/10.1016/j.jallcom.2007.04.150 ER - TY - GEN A1 - Schmälzlin, Elmar A1 - Dongen, Joost T. van A1 - Klimant, Ingo A1 - Marmodée, Bettina A1 - Steup, Martin A1 - Fishahn, Joachim A1 - Geigenberger, Peter A1 - Löhmannsröben, Hans-Gerd T1 - An optical multifrequency phase-modulation method using microbeads for measuring intracellular oxygen concentrations in plants N2 - 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. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 007 Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-12232 ER -