Technical information

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sample is rotated until the atoms are oriented vertically or when the fast scan axis is parallel to the a or b
crystallographic axis. The Proportional Gain should stay at zero except for large scan sizes (~70% of the
scanner range). The system determines the minimum value of the Integral Gain. If you start with a value less
than the system's minimum, you wont get an image.
•Filters, you should be able to obtain an image with the filters off. In general, the filters should be set to off
since filtering during data acquisition affects raw data and height values.
• If difficulty is experienced obtaining and image Withdraw and try a different location on the sample surface,
then
Engage
again. See Section 15.10.1 of the Multimode AFM Manual for Troubleshooting Contact Mode
imaging.
• Once an adequate image of the surface is obtained (see Figures 1-4), make sure the image is real by varying
the Scan Size. The spots observed should scale with Scan Size. The image you will obtain is based on the
"stick-slip" frictional motion of the probe tip (which is why there needs a certain amount of force to be
applied) determined by the spatial periodic corregations on the crystalline lattice surface.
• If you notice a bright vertical band on either end of the image, this is due to the abrupt reversal of direction
of the scanner at the end of each scan line. You can eliminate this by using the following procedure :
1) select
Microscope/Calibrate/Scanner
2) A window will open with the scanner calibration files and in the lower right hand corner is the
"rounding coefficient" which is the percentage of the last portion of each scan line that is not
displayed. This should initially be set equal to 0.0. Increase this to ~0.2 (while not exceeding 0.5) and
this will cut off the last 20% of each scan line.
3) Reset this value back to 0.0 when finished.
•
Capture
the image.
• Sometime a good image can suddenly vanish, possibly due to adsorption of surface contaminants. Try
different XY locations on the same cleaved plane and cleaving the sample a few other times.