Terahertz-Field-Driven Scanning Tunneling Luminescence Spectroscopy

Abstract

Coupling an intense electric field of terahertz (THz) pulse to a scanning tunneling microscope (STM) has opened new avenues for conducting ultrafast electron manipulation and tracking quantum dynamics at the nanometer spatial resolution. Here we combined the THz-field-driven STM with a photon detection system and demonstrated nanospectroscopic investigations of STM-induced luminescence triggered by THz-field-driven electrons. Owing to the abundant spectral information on photons, we were able to separately measure and characterize luminescence from a localized plasmon excited by THz-field- and DC-field-driven inelastic electron tunneling. We revealed that the plasmon excitation by THz-field-driven electrons in our experiment occurred at an extremely high voltage and current region due to the use of intense THz pulses, which would provide a unique experimental platform for exploring the light–matter interactions in a plasmonic nanocavity. Our method also paves the way for investigating quantum energy dynamics accompanying quantum conversions with subpicosecond time and atomic-scale spatial resolution.