Regensburg 2013 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 49: Colloids and Complex Liquids III

CPP 49.4: Vortrag

Freitag, 15. März 2013, 10:30–10:45, H40

Magneto-optical measurement of the rotational relaxation of nickel nanorod colloidal dispersions in ac magnetic fields — •Micha Gratz, Andreas Tschöpe, and Rainer Birringer — Universität des Saarlandes, Saarbrücken, Deutschland

The dynamical magnetic and magneto-optical response of nickel nanorod colloidal dispersions in ac magnetic fields was investigated. The nanorods with an average diameter of ≈ 25 nm and an average length of ≈ 200 nm, were prepared by pulsed electrodeposition of nickel into nanoporous AA0-templates. Dissolution of the alumina layer in dilute NaOH with polyvinylpyrrolidone (PVP) for steric stabilization followed by separation and purification resulted in a stable aqueous dispersion of the nanorods. The microstructure of the nanorods was characterized by electron microscopy and the magnetic properties were optained from static magnetization measurements and field-dependent optical transmission of linearly polarized light. Furthermore, the rotational relaxation in ac magnetic fields was investigated by ac-magnetization and ac-magneto-optical transmission measurements. The experimental results were analyzed by comparison with numerical solutions of the Fokker-Planck equation of rotational diffusion in ac magnetic fields to derive the characteristic relaxation time of the nanorods.