W. Richard Bowen and Nidal Hilal 4

4 1. BAsIC PRINCIPLEs OF ATOMIC FORCE MICROsCOPy
Deflection (nA)
A
Force (nN)
B
60
50
40
30
20
10
0
0 50 100 150 200 250 300 350 400
–10
–20
–30
35
30
25
20
15
10
5
0
–100 –50 0 50 100 150 200 250 300
–5
–10
2.
z-piezo translation (nm)
Distance (nm)
fIgure .4 An example of force curve. Raw data are shown in (a) plotted as displacement
of the z-piezo versus deflection as measured on the photosensitive detector.
Calculation of the cantilever stiffness and sensitivity of the optical lever set-up allow the
raw data to be converted into probe–sample separation distance versus the force, with converted
force curve shown in (b). By convention, for AFM force curves, attractive forces are
portrayed as negative and repulsive forces as positive.
3.
1.