Characterizing Concentrated, Multiply Scattering, and Actively Driven Fluorescent Systems with Confocal Differential Dynamic Microscopy
|Title||Characterizing Concentrated, Multiply Scattering, and Actively Driven Fluorescent Systems with Confocal Differential Dynamic Microscopy, Physical Review Letters 108, 218103|
|Publication Type||Journal Article|
|Year of Publication||2012|
|Authors||Lu, 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|
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.
|Short Title||Phys. Rev. Lett.|