Data taken on a PicoSPM in our lab at ASU is shown in Figure 2. In this particular case, there was good reason to believe that the protein was attached to the surface in globular form. But in general, the experimenter cannot assume that the protein is in its native form. Imaging is required. Figure 4 shows a MAC Mode image of the Titin protein.
Brighter regions correspond to higher amplitude or phase.
The surprising answer is that MAC Mode can image without touching the sample directly. This ability is demonstrated by simultaneous acquisition of the conventional force curve and MAC Mode amplitude. A typical set of data for a MAC Mode tip in water over a clean gold surface are shown in Figure 5.