TY - JOUR A1 - Bartoll, Jens A1 - Nofz, Marianne A1 - Stößer, R. T1 - Generation and conversion of electronic defects in calcium carbonates by UV/Vis light JF - Applied radiation and isotopes N2 - Radical species like CO-2,CO-3, SO-2, and SO-3 can be created by exposing natural and synthetic calcium carbonates to sunlight or to the light of a Hg(Xe) lamp. This poses as a risk for ESR dating of these materials, because the radicals formed by light exposure cannot be distinguished from those generated by radioactivity. Furthermore, paramagnetic centers like SO-2, electrons trapped near Zn2+ or Cd2+ ions, surface defects, and radicals with g?=2.0040, can be bleached in ?-irradiated samples by light and show conversion effects. KW - ESR PY - 2000 DO - https://doi.org/10.1016/S0969-8043(00)00044-0 SN - 0883-2889 SN - 0969-8043 IS - 52 SP - 1099 EP - 1105 PB - Elsevier CY - Amsterdam AN - OPUS4-892 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neamtu, M. A1 - Nadejde, C. A1 - Hodoroaba, Vasile-Dan A1 - Schneider, Rudolf A1 - Panne, Ulrich T1 - Singlet oxygen generation potential of porphyrin-sensitized magnetite nanoparticles: Synthesis, characterization and photocatalytic application JF - Applied Catalysis B: Environmental N2 - Singlet oxygen generation potential of two novel free-base-porphyrin photocatalysts was investigated. The freebase-porphyrin-sensitized Fe3O4 magnetic nanoparticles (MNPs) were tested for the degradation of the model pollutant Bisphenol A (BPA) in aqueous solution, for the first time. MNPs with either cubic or spherical shape were synthesized using the sonochemical approach, followed by sensitizing with photoactive 4,4′,4′′,4′′′- (Porphine-5,10,15,20-tetrayl)tetrakis(benzoic acid) (TCPP). The resulted photocatalysts were characterized in detail by scanning and transmission electron microscopy, Brunauer–Emmett–Teller analysis, spectral techniques and vibrating sample magnetometry. The electron spin resonance experiments have confirmed the high activity of the photocatalysts through the efficient formation of singlet oxygen in solution. The optimum operational parameters for BPA degradation were established as follows: 1.0 μmol L−1 BPA, 1.0 g L−1 of photocatalyst, 100 μmol L−1 H2O2, under UVA irradiation. In these conditions, the results for both photocatalysts revealed that after only 10 min of reaction, over 64% and ca. 90% of BPA have been removed from solution in the absence and presence of H2O2, respectively. Whereas after 60 minutes of treatment, only 24% of BPA in real wastewater effluent samples were removed under UVA irradiation in the absence of H2O2, showing the high complexity of real wastewater. Moreover, both photocatalysts were successfully used for BPA removal in three consecutive runs, without significant loss of catalytic features. KW - Bisphenol A KW - Magnetpartikel KW - Photooxidation KW - Singulettsauerstoff KW - TEM KW - SEM KW - Brunauer-Emmett-Teller KW - Katalysator KW - Abwasser KW - ESR PY - 2018 DO - https://doi.org/10.1016/j.apcatb.2018.03.079 SN - 0926-3373 VL - 232 SP - 553 EP - 561 PB - Elsevier B.V. CY - Amsterdam, NL AN - OPUS4-45267 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stößer, R. A1 - Menzel, Michael A1 - Feist, M. T1 - The fate of Fe3+ ions in the system {AlO(OH)-xerogel/Fe-compounds} after mechanical activation and different thermal treatments studied by Mössbauer, ESR spectroscopy and thermal analysis JF - Hyperfine Interactions KW - Mössbauer KW - ESR KW - Thermal analysis KW - High energy ball milling KW - Activation/deactivation processes KW - Local mechano-chemical reactions KW - Heterogeneous redox reactions PY - 2009 DO - https://doi.org/10.1007/s10751-009-9920-0 SN - 0304-3843 SN - 1572-9540 VL - 190 IS - 1-3 SP - 43 EP - 49 PB - Kluwer CY - Dordrecht AN - OPUS4-19478 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -