Terahertz-Field-Driven Scanning Tunneling Luminescence Spectroscopy
Kensuke Kimura, Yuta Morinaga, Hiroshi Imada, Ikufumi Katayama, K. Asakawa, Katsumasa Yoshioka, Yousoo Kim, Jun Takeda
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.