Such dynamics are frequently encountered in systems with biological or industrial relevance. These imply mean squared displacements with time dependencies that are less than or greater than linear, respectively. However, colloidal particles in more complex situations, for example in the presence of interparticle interactions or external potentials, can show different behavior such as subdiffusion or superdiffusion. The slope is determined by the diffusion coefficient that depends on the temperature, the particle size, and the viscosity of the medium. Free diffusion is characterized by a mean squared displacement which increases linearly with time. A coupling between the translation and rotation is observed and found to depend on the length scale.Ĭolloidal particles undergo random thermal motion. In contrast, the mean squared angular displacement exhibits only small deviations from a linear time dependence but a more detailed analysis reveals discrete angular jumps reflecting the symmetry of the trimer. The translation shows an intermediate subdiffusive regime and a long-time diffusion that slows down upon increasing the modulation of the potential. The particle translation and rotation are quantified by the mean squared (angular) displacement, the van Hove function and other observable quantities. This energy landscape has energy values drawn from a Gamma distribution, a spatial correlation length similar to the particle size and is realized by a random light field, that is a laser speckle pattern. We experimentally investigate the dynamics of a trimer, which consists of three spherical particles, within a random potential energy landscape. In the case of an anisotropic particle, the external potential might not only affect its translation but also its rotation. If a colloidal particle is exposed to an external field, its Brownian motion is modified. 2División de Ciencias e Ingenierías, Departamento de Ingeniería Física, Universidad de Guanajuato, León, Mexico.1Condensed Matter Physics Laboratory, Heinrich Heine University, Düsseldorf, Germany.Escobedo-Sánchez 1, Erick Sarmiento-Gómez 1,2 and Stefan U. Juan Pablo Segovia-Gutiérrez 1, Manuel A.
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