Dresden 2011 – scientific programme

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MA: Fachverband Magnetismus

MA 12: Magnetic Particles/ Clusters II

MA 12.2: Talk

Monday, March 14, 2011, 17:15–17:30, HSZ 103

Fe oxide nanoparticles in dispersion measured by XAS — •Anne Warland, Carolin Antoniak, Masih Darbandi, Claudia Weis, Werner Keune, and Heiko Wende — Faculty of Physics and CeNIDE, University of Duisburg-Essen, Germany

Due to the wide range of biomedical applications like e.g., targeted drug delivery and hypothermia treatment, magnetic nanoparticles are the subject of intense research. Fe oxide nanoparticles are often used as contrast enhancers in the MRI. We investigated Fe₃O₄ (magnetite) nanoparticles as they are biocompatible and their surface can be functionalized. Magnetite consists of Fe³⁺ and Fe²⁺ ions in tetrahedral and octahedral lattice sites giving rise to a clear multiplet structure in the x-ray absorption spectrum at the Fe L_3,2 edges. We synthesized Fe oxide nanoparticles using a water-in-oil microemulsion technique, which yields nanoparticles with a narrow size distribution. Bare and silica coated Fe oxide nanoparticles of a core size of 7nm dispersed in ethanol have been investigated by means of x-ray absorption spectroscopy (XAS) allowing to disentangle the contributions of the Fe²⁺ and Fe³⁺ ions and therefore, to estimate the amount of Fe₃O₄ in the particles. Due to a special experimental setup (Liquidrom chamber)[1] provided at BESSY, the particles can be measured directly in dispersion. In case of the silica coated particles a high amount of magnetite was obtained. In contrast, the bare nanoparticles showed indications of further oxidation into Fe₂O₃. -Supported by DFG(SFB 445,WE 2623/3-1) and Helmholtz-Zentrum Berlin.

[1] Aziz Bekhit E F 2007, Dissertation FU Berlin.