In: Nano Letters, 2009, vol. 9, no. 10, p. 3527–3531
We study the diffusion of a metal nanoparticle in the nonconservative force field of an optical vortex lattice. Radiation pressure in the vortex array is shown to induce a giant enhancement over the free thermal diffusion. Langevin dynamics simulations show that the diffusion coefficient of (50 nm radius) gold particles at room temperature is enhanced by 2 orders of magnitude at power densities...
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In: Optics Express, 2009, vol. 17, no. 16, p. 13904-13917
Laser speckle imaging (LSI) based on the speckle contrast analysis is a simple and robust technique for imaging of heterogeneous dynamics. LSI finds frequent application for dynamical mapping of cerebral blood flow, as it features high spatial and temporal resolution. However, the quantitative interpretation of the acquired data is not straightforward for the common case of a speckle field formed...
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In: The Journal of Physiology, 2009, vol. 587, p. 3153-3158
Two-photon microscopy is a powerful method in biomedical research that allows functional and anatomical imaging at a subcellular resolution in vivo. The technique is seriously hampered by absorption and scattering of light by blood, which prevents imaging through large vessels. Here, we demonstrate in the rat cerebral cortex that blood replacement by perfluorocarbon emulsion, a compound also used...
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In: Journal of Physics: Condensed Matter, 2009, vol. 21, p. 332102
We discuss the measurable structure factor SM(q) of highly concentrated nanoemulsions in a glassy amorphous state. Neutron scattering data show that the primary structure factor peak decreases with increasing concentration and eventually drops below unity. We find very good quantitative agreement between the experimental SM(q) and analytical...
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In: Langmuir, 2009, vol. 25, no. 2, p. 716–723
The frequency-dependent shear modulus of aqueous wormlike micellar solutions of cetylpyridinium chloride (CPyCl) and sodium salicylate (NaSal) has been measured over a broad frequency range from 10⁻² to 10⁶ rad/s using diffusing wave spectroscopy (DWS) based tracer microrheology as well as mechanical techniques including rotational rheometry and oscillatory squeeze flow. Good agreement...
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In: European Physical Journal E, 2009, vol. 28, no. 2, p. 165-171
We present a light scattering study of aqueous suspensions of microgel particles consisting of poly(N-Isopropyl-Acrylamide) cross-linked gels. The solvent quality for the particles depends on temperature and thus allows tuning of the particle size. The particle synthesis parameters are chosen such that the resulting high surface charge of the particles prevents aggregation even in the...
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In: Physical Review Letters, 2008, vol. 100, p. 178304
We determine the structure of charge-stabilized colloidal suspensions at low ionic strength over an extended range of particle volume fractions using a combination of light and small angle neutron scattering experiments. The variation of the structure factor with concentration is analyzed within a one-component model of a colloidal suspension. We show that the observed structural behavior...
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In: Applied Physics Letters, 2007, vol. 91, no. 17, p. 171904
Amorphous photonic materials based on dense assemblies of high refractive index spherical particles are presented. Light transmission through these photonic glasses shows a nontrivial wavelength dependence. The transmission spectra can be quantitatively reproduced by modeling the optical properties starting from their building blocks. Our results emphasize the relevance of including short range...
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In: Current Opinion in Colloid & Interface Science, 2007, vol. 12, no. 1, p. 50-57
In this article we review some of the most important new developments in light scattering that have emerged over the past 10 years. Some of the new methods substantially extend the range of accessible time and length scales. Different cross-correlation methods are now available to suppress multiple scattering over a large concentration range. Novel low coherent light sources on the other hand...
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In: Optics Communications, 2008, vol. 281, no. 1, p. 18-22
We discuss the impact of the scattering anisotropy parameter on the path length distribution of multiply scattered light. A quantitative treatment based on the radiative transfer equation is compared to an extended photon diffusion formalism. We compare both models with diffusing-wave spectroscopy measurements using randomly polarized light.
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