Berlin 2005 – wissenschaftliches Programm
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AKB: Biologische Physik
AKB 50: Imaging and Microscopy
AKB 50.3: Vortrag
Montag, 7. März 2005, 16:30–16:45, TU H2013
Single fluorescent molecules imaged by the near-field of a metal tip — •Heinrich Gotthard Frey1 and Reinhard Guckenberger2 — 1Universität Bielefeld, Fakultät für Physik, Universitätsstr. 25, 33615 Bielefeld, Germany — 2Max-Planck-Institut für Biochemie, Abt. Molekulare Strukturbiologie, Am Klopferspitz 18, 82152 Martinsried, Germany
We show experimentally that a sharp metal tip, illuminated by a close-by aperture, can be used as high resolution optical near-field probe with an unique combination of good qualities [1]:
Single Cy3 molecules covalently bound to DNA were imaged as test sample. The fluorescence images of such single molecules show patterns with one or two peaks. The width of these peaks can be as small as 10 nm. A simple model allows to explain these patterns. By fitting model calculations to the data, the positions of the dye molecules can be determined with an accuracy better than 1 nm. The 3D orientation of the dyes is also provided by the fit. The positions of two single molecules with only 12 nm distance and overlapping fluorescence patterns could still be determined. The metal tip also provides a topographical signal simultaneously to the optical one. The topographical and optical images have nearly the same resolution and the lateral shift between these images is smaller than the resolution. So, optical and topographical information can be measured simultaneously at the same point, what is of high importance for time dependent measurements.
[1] H.G. Frey, S. Witt, K. Felderer, and R. Guckenberger, Phys. Rev. Lett., in press