Correlation between charge-transfer and rotation of C_(60) on WO2/W(110)

摘要

Understanding molecular switching between different charge states is crucial to further progress in molecule-based nano-electronic devices. Herein we have employed scanning tunnelling microscopy to visualize different charge states of a single C_(60) molecule within a molecular layer grown on the WO2/ W(110) surface. The results obtained demonstrate that individual C_(60) molecules within the layer switch between neutral and negatively charged states in the temperature range of 220-260 K over the time scale of the experiment. The charging of the C_(60) causes changes in the local density of electron states and consequently a variation in tunnelling current. Using density functional theory calculations, it was found that the charged state corresponds to the negatively charged C_(60)~, which has accepted an electron. The switching of the molecule into the charged state is triggered continuously by tunnelling electrons when the STM tip is static above an individual C_(60) molecule with a bias applied. Molecular movement accompanies the molecule's switching between these states.