Dell 3100 Especificações descarregar pdf (Página 246)

Force Imaging

Force Calibration (Contact Mode AFM)

226 Dimension 3100 Manual Rev. D

When the Data type is set to Height with the feedback gains set high, the tip tracks the sample

surface with nearly constant deﬂection of the cantilever. When the cantilever deﬂection is constant,

the force is constant and the force calculation above determines the contact force between the tip

and the surface over the entire scan area.

Force calculations are not as straightforward on images captured with the Data type set to

Deﬂection. When collecting deﬂection data, the feedback gains are ideally set low so the sample

stays at a nearly constant position relative to the cantilever holder. In this case, the cantilever

deﬂection (and therefore the force applied to the sample) varies as features on the surface are

encountered. The contact force can be calculated by adding the deﬂection data from the image to

before multiplying by the spring constant: F = k (deﬂection image data + d). Note that the

Sensitivity parameter must be accurate—that is, previously determined and entered—before the

deﬂection data will be accurate.

A simple alternative to calculating force is to follow these ﬁve steps:

1. Set sensitivity using the mouse.

2. Change units to metric.

3. Count vertical units from Setpoint to VCS min.

4. Multiply by Deflection Scale (adjacent to plot).

5. Multiply by the spring-constant, k.

1 2 ... 241 242 243 244 245 246 247 248 249 250 251 ... 375 376

Sem comentários

Dell 3100 Especificações Página 246