Right image shows higher magnification view of the steps.
In FM non-contact AFM mode the cantilever is driven at a fixed amplitude of vibration and changes in its vibration frequency are detected. The FM detector measures much weaker force gradients than can be sensed using conventional AM detectors over a given bandwidth. The sample in this image was cleaved in air and transferred to vacuum 30 minutes later. The step structure visible in the image shows step edges which fluctuate about a mean position, with kinks made up of steps in the directions. The upper terrace region shows recrystallized islands bounded by these steps.