Selecting A Force Modulation Tip - Veeco 004-210-000 Instruction Manual

11.6.2 Selecting a Force Modulation Tip

The key consideration when selecting a force modulation cantilever is its spring constant. Ideally,
the cantilever must have a spring constant which compliments the pliancy of the two contrasting
materials (or close to the pliancy of one, but not the other). This way, the tip indents into one
material more than the other providing good force modulation image contrast. If the tip is so stiff
that it indents equally into both materials, or so soft that it indents neither material, then you will
not see contrast in the force modulation image. Instead, the image will consist primarily of edge and
frictional artifacts. It may take experimentation to find a cantilever that matches the sample's
requirements. For rubber and plastic samples Veeco recommends using 225µm long force
modulation (Model # FESP) silicon cantilevers. For more delicate, samples, use 450µm long silicon
cantilevers or silicon nitride cantilevers. For hard materials, use stiffer tips like the 125µm single
crystal silicon TappingMode tips.
Veeco offers cantilevers with a wide range of spring constants (see
depends upon how stiff the sample is For samples of unknown hardness, start with a force
modulation cantilever (Model FESP) and determine whether the tip is sufficiently stiff then adjust
accordingly.
Cantilever
Standard Silicon Nitride
Oxide-sharpened
Silicon Nitride
Contact AFM
Etched Silicon
Force Modulation
Etched Silicon
TappingMode
Etched Silicon
TappingMode
Etched Silicon
Rev. B
Table 11.6a Force Modulation Tips
Model Cantilever
No. Length
NP, DNP 100—200µm
NP-S, 100—200µm
DNP-S
ESP 450µm
FESP 225µm
LTESP 225µm
TESP 125µm
MultiMode SPM Instruction Manual
Force Imaging
Force Modulation
Table 11.6a). Choosing a tip
Spring
Constant
0.01—0.6 N/m
0.01—0.6 N/m
0.02—0.1 N/m
1—5 N/m
20—70 N/m
20—100 N/m
205