Optical Sciences

Biomolecules and nanostructures

The Optical Sciences group studies the interaction of light and matter. Our current focus is on detection and sensing/imaging with an emphasis on the development of integrated photonics. We are part of Twente University's Department of Science and Technology and member of the MESA+ institute.

 

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

(full pdf)

Garcia-Parajo MF, Veerman JA, Ruiter AGT, van Hulst NF
ULTRAMICROSCOPY
vol 71 issue 1-4: p311-p319 MAR 1998

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. (C) 1998 Elsevier Science B.V. All rights reserved.
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