Band excitation in scanning probe microscopy: sines of change

In the three decades since scanning probe microscopy (SPM) methods have entered the scientific arena, they have become one of the main tools of nanoscale science and technology by offering the capability for imaging topography, magnetic, electrical and mechanical properties on the nanometre scale. The vast majority of force-based SPM techniques to date are based on single-frequency sinusoidal excitation and detection. Here, we illustrate the intrinsic limitations of single-frequency detection that stem from the fundamental physics of dynamic systems. Consequently, many aspects of nanoscale materials functionality including quantitative mechanical, magnetic and electrical measurements, as well as probing dissipative interactions, remain unexplored. Band excitation is illustrated as a universal alternative to traditional single-frequency techniques that allows quantitative and reliable studies of dissipative and conservative phenomena, and can be universally applied to all ambient and liquid SPM methods.