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

Research output: Contribution to journalArticle

  • Peter J. Lu
  • Fabio Giavazzi
  • Thomas Angelini
  • Emanuela Zaccarelli
  • Frank Jargstorff
  • Andrew B Schofield
  • James Wilking
  • Mark Romanowsky
  • David Weitz
  • Roberto Cerbino

Related Edinburgh Organisations

Original languageEnglish
Article number218103
Number of pages5
JournalPhysical Review Letters
Publication statusPublished - 22 May 2012


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.

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