Ultrafast time resolution in scanning probe microscopy of repetitive phenomena

The high-speed dynamics of microscopic structures are currently of great interest, both from a scientific perspective, where they represent a largely unexplored regime, and in technology, where the behavior of active electronic, optical, and magnetic devices is governed by dynamical properties. These interests have stimulated recent work on combinations of scanning probe microscopy and ultrafast laser techniques. Conventional scanning probe microscopy alone lacks the bandwidth required for experimental studies of the dynamics of nanoscale systems, while standard optical methods do not offer the necessary spatial resolution. In the case of repetitive phenomena, stroboscopic approaches applied to scanned probes yield simultaneous high temporal and spatial resolution. We discuss two such schemes for scanning tunneling microscopy.