University of Tokyo-led researchers showed that long-wavelength terahertz (THz) spectroscopy can detect motion of single molecules, not just molecular ensembles. They used a single-molecule transistor design, where pairs of metal electrodes trap isolated C60 molecules, focus the THz beam onto them, and measure current change caused by THz-induced oscillation. Two vibrational peaks were recorded. The measurement was sensitive enough to register slight peak-splitting caused by electron charging. This could promote wider use of THz spectroscopy.