9:35 AM - 9:50 AM
▼ [13a-B508-4] Charge dependent vibration of a single water molecule encapsulated in a C60 fullerene
Keywords:single molecule, water, charge dependent vibration
Resolving the charge transport in molecules improves our knowledge on several molecular processes, including chemical reactions, catalysis, and potentially even processes in living organisms. When a molecule is charged, both the electronic structures and vibrational dynamics of the molecule is changed. However, it is very difficult to see such dynamical charge-induced changes.
Here, we have investigated the charge-dependent electron transport through single H2O@C60 molecules [1] by using the single molecule transistor (SMT) geometry [2]. As shown in Fig. 1(a), the very sharp metal electrodes work as THz antennas to tightly confine THz radiation in the gap region [2], and the fullerene works as a natural cage to trap a H2O molecule. Furthermore, the gate electrode is used to tune the electron number on the molecule, which makes it possible to study charge-induced dynamics of a H2O@C60 SMT. Fig. 1(b) shows the Coulomb stability diagram of a H2O@C60 SMT. The crossing pattern indicates that we capture a single molecule in the nanogap. Then we preformed THz spectroscopy on such H2O@C60 SMT and obtained the charge-dependent spectra of the THz-induced photocurrent, as shown in Fig. 1(c). The peak at 5 meV (dashed line in Fig. 1(c)) appears when an electron is added to the H2O@C60 molecule. The present measurement clearly reveals charge-dependent THz vibration of a single molecule. Also note that the endofullerene structure together with nanogap electrodes can provide a sub-nm-size laboratory for studying single-molecule dynamics.
Here, we have investigated the charge-dependent electron transport through single H2O@C60 molecules [1] by using the single molecule transistor (SMT) geometry [2]. As shown in Fig. 1(a), the very sharp metal electrodes work as THz antennas to tightly confine THz radiation in the gap region [2], and the fullerene works as a natural cage to trap a H2O molecule. Furthermore, the gate electrode is used to tune the electron number on the molecule, which makes it possible to study charge-induced dynamics of a H2O@C60 SMT. Fig. 1(b) shows the Coulomb stability diagram of a H2O@C60 SMT. The crossing pattern indicates that we capture a single molecule in the nanogap. Then we preformed THz spectroscopy on such H2O@C60 SMT and obtained the charge-dependent spectra of the THz-induced photocurrent, as shown in Fig. 1(c). The peak at 5 meV (dashed line in Fig. 1(c)) appears when an electron is added to the H2O@C60 molecule. The present measurement clearly reveals charge-dependent THz vibration of a single molecule. Also note that the endofullerene structure together with nanogap electrodes can provide a sub-nm-size laboratory for studying single-molecule dynamics.