Characterizing Concentrated, Multiply Scattering, and Actively Driven Fluorescent Systems with Confocal Differential Dynamic Microscopy

TitleCharacterizing Concentrated, Multiply Scattering, and Actively Driven Fluorescent Systems with Confocal Differential Dynamic Microscopy, Physical Review Letters 108, 218103
Publication TypeJournal Article
Year of Publication2012
AuthorsLu, Peter J., Fabio Giavazzi, Thomas E. Angelini, Emanuela Zaccarelli, Frank Jargstorff, Andrew B. Schofield, James N. Wilking, Mark B. Romanowsky, David A. Weitz, and Roberto Cerbino
Refereed DesignationRefereed
Issue21
Date Published5/2012
ISSN1079-7114
Abstract

We introduce confocal differential dynamic microscopy (ConDDM), a new technique yielding information comparable to that given by light scattering but in dense, opaque, fluorescent samples of micron-sized objects that cannot be probed easily with other existing techniques. We measure the correct wave vector q-dependent structure and hydrodynamic factors of concentrated hard-sphere-like colloids. We characterize concentrated swimming bacteria, observing ballistic motion in the bulk and a new compressed-exponential scaling of dynamics, and determine the velocity distribution; by contrast, near the coverslip, dynamics scale differently, suggesting that bacterial motion near surfaces fundamentally differs from that of freely swimming organisms.

URLhttp://prl.aps.org/abstract/PRL/v108/i21/e218103
DOI10.1103/PhysRevLett.108.218103
Short TitlePhys. Rev. Lett.
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Peter J. Lu  |  Harvard University  |  Cambridge, MA 02138 USA |  plu_at_fas.harvard.edu