We probe the roto-translational Brownian motion of optically anisotropic particles suspended in water with a simple and straightforward optical microscopy experiment that does not require positional or rotational particle tracking. We acquire a movie of the suspension placed between two polarizing elements and we extract the translational diffusion coefficient D T and the rotational diffusion coefficient D R from the analysis of the temporal correlation properties of the spatial Fourier modes of the intensity fluctuations in the movie. Our method is successfully tested with a dilute suspension of birefringent spherical colloidal particles obtained by polymerizing an emulsion of droplets of liquid crystal in a nematic phase, whose roto-translational dynamics is found to be well described by theory. The simplicity of our approach makes our method a viable alternative to particle tracking and depolarized dynamic light scattering.

Simultaneous characterization of rotational and translational diffusion of optically anisotropic particles by optical microscopy / F. Giavazzi, C. Haro Pérez, R. Cerbino. - In: JOURNAL OF PHYSICS. CONDENSED MATTER. - ISSN 0953-8984. - 28:19(2016 May 18). [10.1088/0953-8984/28/19/195201]

Simultaneous characterization of rotational and translational diffusion of optically anisotropic particles by optical microscopy

F. Giavazzi
Primo
;
R. Cerbino
Ultimo
2016

Abstract

We probe the roto-translational Brownian motion of optically anisotropic particles suspended in water with a simple and straightforward optical microscopy experiment that does not require positional or rotational particle tracking. We acquire a movie of the suspension placed between two polarizing elements and we extract the translational diffusion coefficient D T and the rotational diffusion coefficient D R from the analysis of the temporal correlation properties of the spatial Fourier modes of the intensity fluctuations in the movie. Our method is successfully tested with a dilute suspension of birefringent spherical colloidal particles obtained by polymerizing an emulsion of droplets of liquid crystal in a nematic phase, whose roto-translational dynamics is found to be well described by theory. The simplicity of our approach makes our method a viable alternative to particle tracking and depolarized dynamic light scattering.
Brownian motion; microscopy; rotational diffusion; scattering; translational diffusion; condensed matter physics; materials science (all)
Settore FIS/07 - Fisica Applicata(Beni Culturali, Ambientali, Biol.e Medicin)
Settore FIS/03 - Fisica della Materia
   Anisotropies and non equilibrium in soft matter: routes to the self assembly of advanced materials
   ANISOFT
   MINISTERO DELL'ISTRUZIONE E DEL MERITO
   RBFR125H0M_002
18-mag-2016
19-apr-2016
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/428626
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