Reversible light-induced cluster formation of magnetic colloids

Abstract We report on the new observation of fully reversible light-induced cluster formation in sterically stabilized kerosene-based magnetite (Fe3O4) ferrofluids. When illuminated with visible light within their optical absorption band, μm-sized clusters are formed which contain of the order of 107 individual colloidal particles. After switching the illumination off, the attractive forces disappear and the clusters dissolve on a time scale of 1 min. Linear chains of several 100 μ m length are formed upon illumination in the presense of a weak magnetic field (1 mT). This new effect may be useful for patterning and optically triggered reversible assembly of controlled nano- and microstructures.

[1]  Wu,et al.  Field-Induced Structures in Ferrofluid Emulsions. , 1995, Physical review letters.

[2]  I. Turek,et al.  The effect of self-diffraction in magnetic fluids , 1999 .

[3]  V. Fertman.  Magnetic fluids guidebook : properties and applications , 1990 .

[4]  N. Tabiryan,et al.  SORET FEEDBACK IN THERMAL DIFFUSION OF SUSPENSIONS , 1997 .

[5]  Flament,et al.  Rayleigh-taylor instability with magnetic fluids: experiment and theory , 2000, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[6]  U. Kreibig,et al.  Light induced aggregation of metal clusters , 1993 .

[7]  Bourdon,et al.  Forced Rayleigh experiment in a magnetic fluid. , 1995, Physical review letters.