ULTRAFAST TIME RESOLUTION IN SCANNING-TUNNELING-MICROSCOPY

Recent work combining scanning probe microscopy with ultrafast laser t echniques has been stimulated by interest in the high speed dynamics o f microscopic structures. The goal is to achieve state-of-the-art temp oral and spatial resolution simultaneously with a single probe. Conven tional scanning probe microscopy lacks the bandwidth required for expe rimental studies of the dynamics of nanoscale systems, while standard optical methods do not offer the necessary spatial resolution. It is n ow possible to employ stroboscopic methods with scanned probes to yiel d high combined resolution for studies of repetitive phenomena. After a brief review of the development of the field, we discuss two methods enabling the extraction of fast signals from the scanning tunneling m icroscope: junction mixing and distance modulation. (C) 1997 Elsevier Science B.V.