Regensburg 2007 – scientific programme

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O: Fachverband Oberflächenphysik

O 15: Methods: Scanning Probe Techniques II

O 15.9: Talk

Monday, March 26, 2007, 16:15–16:30, H41

Design of a High-Frequency Electric-Force Scanning Force Microscope for Vibration Spectroscopy at Single Macromolecules — Patrick Steffen, Ivo Knittel, and •Uwe Hartmann — Fachbereich Experimentalphysik, Im Stadtwald, Geb. C6.3, 66041 Saarbrücken

Mechanical properties of single macromolecules on timescales down to sub-nanoseconds are relvant to the understanding of the biological function of cell components. For an effective mechanical spectrocsopy at single macromolecules, a local excitation, with high amplitude and narrow bandwidth is necessary. In addition, detection should as well be local, and with narrow bandwidth. A complete microscope design is discussed in this contribution. A mechanical resonance of a sample macromolecule is excited by a charged AFM-tip. The oscillating sample molecule leads to an additional static force because of nonlineal tip-sample interaction. The size of this force is estimated by analytic and numerical methods. For the force modulation, signal-to-noise ratios and stabiltiy are investigated for several variants. The optimized design is suggested, incuding a suitable waveguide, and a suitable modulation of the exciting microwave.