THz Scanning Tunnelling Microscopy

We employ visible to infrared ultrashort laser pulses for photoexcitation of the STM. Subsequent gating of the tunnel junction by ultrabroadband single-cycle THz-pulses allows for the local probing of the photoexcited state, providing new insight into the atomic-scale variations of the dynamics of charge carriers. Moreover, the application of a quasi-static femtosecond voltage pulse via THz-pulse excitation of the tunnel junction allows for the ultrafast injection of electrons into otherwise inaccessible electronic states. THz-controlled femtosecond electron injection in the STM, thus, provides a tool for probing ultrafast electronic and optoelectronic processes on the nanometer scale and below.