NT-MDT Solver Next - Saving Measurement Data; Afm Spectroscopies; Force-Distance Spectroscopy; Selecting the Function to be Measured

Chapter 7. Performing Measurements
141
7.5. AFM Spectroscopies
This section discusses the spectroscopy curves measurement procedures.
Prior to conducting spectroscopy measurements it is recommended to perform a
preliminary scan.
The measurement procedures for various types of spectroscopy are similar. As an example,
this section considers one of the techniques – Force Spectroscopy Force–Distance. In the
sections concerning other spectroscopy techniques a general description of the procedure is
given together with comments on the differences in completing certain operations.
7.5.1. Force-distance Spectroscopy
In Force-distance spectroscopy cantilever deflection is measured as a function of the
scanner extension, i.e. the DFL(Height) curve is obtained.
After the probe has touched the surface any variation in the voltage applied to the z-contact
of the scanner (the Height signal) results in a proportional change in the DFL signal. Using
the DFL(Height) function and assuming that the cantilever stiffness is known one can
calculate the forces acting on the probe in the measurement point including adhesive force.
Contact probes shall be used for force-distance spectroscopy. However, using too “soft”
cantilever at high humidity may cause “sticking”.
Spectroscopy measurements could be started as soon as the probe has been approached to
the surface using the contact mode (see i. 7.1 “Contact AFM” on p. 55).
Basic operations:
The general procedure on force-distance spectroscopy is represented by the following
sequence of basic operations:
1. Selecting the Function to be Measured, i.e. selecting a function and its argument
(see i. 7.5.1.1 on p. 142);
2. Selecting Points for Spectroscopy (see i. 7.5.1.2 on p. 144);
3. Starting the Measurements (see i. 7.5.1.3 on p. 147);
4. Viewing Spectroscopy Data and processing them (see i. 7.5.1.4 on p. 147);
5. Calculating Adhesion Force (see i. 7.5.1.5 on p. 150);
6. Saving Measurement Data (see i. 7.5.1.6 on p. 152);
A detailed description of these basic operations is given below.