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CPM Seminar
Dr. Sabine Hild
Experimentelle Physik Measuring adhesive Force by Scanning Force Microscopy (SFM) is a senstitve methode to characterize hereogeneous surfaces by chemical contrast. A commonly used technique to do this is taking taking force vs. distance curves (FDC) by SFM and estimate adhesive force by the detected pull-off-force. Nevertheless, this method does not appear to be convenient for imaging surface properties with lateral resolution, because of long imaging times and a high amount of data. To overcome these disadvantages a new operation method called "Pulsed Force Mode" has been developed. Here a sinusoidal z-modulation is used to perform force vs. distance curves. This allows to increase the imaging speed in such a manner that the time for taking an image is comparable to contact mode imaging. To reduced the amount of data without sacrificing the essential information a few characteristic points of the curve, e. g. maximum and minimum value of the FDC, are recorded by sample & hold circuits. This enables the simultaneous imaging of topography and adhesive force with high lateral resolution. Local elastic behavior or surfaces charges can also be recorded. The suitability of this new method for the investigation of heterogeneous surfaces with respect to chemical contrast will be shown by different organic surfaces like polymer blends or thin organic films.
Thursday, November 13th, 15:30 |