31
- set P-Gain to 0 and I-Gain to 2 in ‘Feedback Panel’.
- apply these new values by using
.
- to visualize the current information, choose ‘Current’ as input in the
‘View Panel’.
Notice that ‘Z-Range’ is now called ‘InputRange’ and the corresponding
axis is labelled ‘nA’ instead of ‘nm’.
- when displaying a ‘TopView’ image, use in ‘ViewPanel’, ‘Visible Input
Range’
in order to enhance the image’s contrast.
Judging the quality of the images
From the quality of the measured images the quality of the tip and conse-
quently that of the tunneling contact can be observed. A good tunneling
contact is necessary for high quality images of atomic resolution.
• If temperature variations are present they cause so called ‘thermal drift’.
Consequently the images are stretched. This effect can be observed when
e.g. the upward scan is very different to the downward scan showing two
differently distorted lattices.
Consequent upward and downward scan showing thermal drift
Thermal drift is very clearly perceptible on an atomic scale. Variations of 1/
10°C already cause variations in the length of e.g. the sample holder (steel)
of several nanometers!
To decrease thermal drift, keep the measurement running for some time to
let the system stabilize (up to about one hour).
F
IRST
M
EASUREMENTS
J
UDGING
THE
QUALITY
OF
THE
IMAGES
Summary of Contents for easyScan E-STM
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