AFM Imaging?Reliable or Not?: Validation and Verification of Images in Atomic Force Microscopy

Atomic force microscopy (AFM) was invented in 1986 [1]. By using a compliant flexure probe, such as a microcantilever beam with a sharp tip at one end, the interaction forces between atoms on the probe-tip and atoms on the material surface can be measured (see Figure 1). Since its invention, the simple strategy of using a beam with a sharp tip is now being employed to measure many diverse properties of matter at the nanometer scale including electrical, magnetic, chemical, and mechanical properties [2]. Many different operational modes have evolved that have demonstrated the versatility of the basic underlying principle [3]. AFM has led to many seminal insights in science such as obtained in the recent imaging of pentacene molecules with subatomic resolution [4].