Single-molecule fluctuations in a tunnel junction: A study by scanning-tunnelling-microscopy–induced luminescence

Time-resolved measurements are essential to understand dynamic processes. The property of a tunnel junction to emit light, even in a liquid, offers an optical route to study fast phenomena occurring in this model nanoscopic system. We apply time-correlated two-photon counting to the light emitted by a STM junction immersed in a liquid. We analyze the diffusion of a single molecule at room temperature with sub-nanosecond time resolution, and its influence on the tunnelling process