Single-molecule laser nanospectroscopy with micro–electron volt energy resolution
Hiroshi Imada, Miyabi Imai-Imada, Kuniyuki Miwa, Hidemasa Yamane, Takeshi Iwasa, Yusuke Tanaka, Naoyuki Toriumi, Kensuke Kimura, Nobuhiko Yokoshi, Atsuya Muranaka, Masanobu Uchiyama, Tetsuya Taketsugu, Yuichiro K. Kato, Hajime Ishihara, Yousoo Kim
Abstract
Ways to characterize and control excited states at the single-molecule and atomic levels are needed to exploit excitation-triggered energy-conversion processes. Here, we present a single-molecule spectroscopic method with micro-electron volt energy and submolecular-spatial resolution using laser driving of nanocavity plasmons to induce molecular luminescence in scanning tunneling microscopy. This tunable and monochromatic nanoprobe allows state-selective characterization of the energy levels and linewidths of individual electronic and vibrational quantum states of a single molecule. Moreover, we demonstrate that the energy levels of the states can be finely tuned by using the Stark effect and plasmon-exciton coupling in the tunneling junction. Our technique and findings open a route to the creation of designed energy-converting functions by using tuned energy levels of molecular systems.