On the progress of ultrafast time-resolved THz scanning tunneling microscopy

Scanning tunneling microscopy combined with terahertz (THz) electromagnetic pulses and its related technologies have developed remarkably. This technology has atomic-level spatial resolution in an ultrahigh vacuum and low-temperature environment, and it measures the electrical dynamical behavior of a sample's surface with femtosecond temporal resolution. In particular, it has been used to image the diffusion and relaxation dynamics of electrons in real time and real space and even instantaneously control molecular motions. In this Perspective, we focus on recent progress in research and development of ultrafast time-resolved THz scanning tunneling microscopy and its application to materials research.