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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 48: Nanoparticles and Composite Materials II
CPP 48.8: Vortrag
Freitag, 18. März 2011, 12:15–12:30, ZEU 114
XAS and XMCD Studies on Novel Iron Oxide Nanoparticles as Magnetic Resonance Imaging (MRI) Contrast Enhancers — •Patrick Stumpf1, Christina Graf1, Detlef Schmitz2, Christian Goroncy1, Marie Küssner1, and Eckart Rühl1 — 1Institut für Chemie und Biochemie - Physikalische und Theoretische Chemie, Freie Universität Berlin, Takustr. 3, D-14195 Berlin — 2Helmholtz-Zentrum Berlin, Albert-Einstein-Str. 15, D-12489 Berlin
Iron oxide (FeOx) nanoparticles are applied in medical research as contrast agents in magnetic resonance imaging (MRI) where they reduce the spin-spin relaxation time (T2 time) of absorbing tissue. Their magnetic properties strongly depend on the particle size and shape, as well as the surface structure and the modification of the iron oxide core. Therefore, monodisperse, spherical iron oxide (Fe3O4/Fe2O3) nanoparticles were prepared by a high temperature approach using iron oleate precursors prepared in oxygen-free and oxygen-rich surrounding. These freshly synthesized particles are tempered in an oxygen-free or oxygen-rich environment to improve their crystalline order and to change their magnetite-to-maghemite ratio. Magnetic relaxometry measurements are carried out to evaluate if these structural changes influence the spin-spin (T2) and spin-lattice (T1) relaxation times of the nanoparticles. NEXAFS (Near Edge X-Ray Absorption Fine Structure) and XMCD (X-Ray Magnetic Circular Dichroism) experiments were used to investigate local structural and electronic properties of the iron oxide particles before and after post-synthetic oxidative and thermal treatment. These results are correlated with relaxometry data.