Atomic force microscopy (AFM) has become a mainstream nanotechnology tool across both materials and life sciences. The dominant mode of AFM operation is known as AC mode, dynamic mode, or perhaps most commonly, tapping mode. Though several distinct and important variations exist under these collective names, what they all share is that the AFM cantilever is oscillated at or near its resonance frequency and that these oscillations are measured as the tip of the cantilever interacts with the sample. The most common method of cantilever actuation is known as piezoacoustic excitation, where a nearby piezo is used to mechanically shake the cantilever. Here we diccuss photothermal excitation, an alternate drive mechanism that uses a power-modulated laser to directly excite cantilever oscillation, outline the ways in which this method is superior to piezoacoustic excitation, and present examples of these advantages.
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