Near-field optical and shear-force microscopy of single fluorophores and DNA molecules

M.F. Garcia-Parajo, J.-A. Veerman, A.G.T. Ruiter, N.F. van Hulst

Research output: Contribution to journalArticleAcademicpeer-review

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Photodynamics of individual fluorescence molecules has been studied using an aperture-type near-field scanning optical microscope with two channel fluorescence polarisation detection and tuning fork shear-force feedback. The position of maximum fluorescence from individual molecules could be localised with an accuracy of 1 nm. Dynamic processes such as translational and rotational diffusion were observed for molecules adsorbed to a glass surface or embedded in a polymer host. The in-plane molecular dipole orientation could be determined by monitoring the relative contribution of the fluorescence signal in the two perpendicular polarised direct:ions. Rotational dynamics was investigated o­n 10 ms-1000 s timescale. Shear-force phase feedback was used to obtain topographic imaging of DNA fragments, with a lateral and vertical resolution comparable to scanning force microscopy. A DNA height of 1.4 nm has been measured, an indication of the non-disturbing character of the shear force mechanism.
Original languageEnglish
Pages (from-to)311-319
Number of pages9
Issue number1-4
Publication statusPublished - 1998


  • Dynamics
  • Photodynamics
  • Optical microscopy
  • Molecules
  • Fluorescence
  • DNA
  • Diffusion
  • Shear force microscopy
  • Fluorophores


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