Abstract
The Z-scan experimental technique is used to measure the concentration-dependent Soret coefficient of surfacted magnetic nanoparticles in water [pure ferrofluid (FF)] and in a micellar lyotropic mixture [lyotropic doped with ferrofluid (FL)]. In both cases, the magnetic-particle contribution to the Soret coefficient is shown to be proportional to its concentration. In the case of the ferrofluid-doped lyotropic system, it was possible to evaluate the Soret coefficient associated with the micelles under a temperature gradient. The thermal diffusion coefficients keep the relation . The Soret effective mobilities evaluated are and for the pure ferrofluid and micellar media, respectively. From a nanoscopic point of view, the smaller value of when compared to could be pictured as an additional resistance of the micellar medium to the particle’s flow imposed by the temperature gradient. This procedure gives a new way of determining the Soret coefficient of a weakly absorbing medium.
© 2006 Optical Society of America
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