Driving a Single Chemisorbed Molecule-Rotor by Thermal Energy and Tunneling Electrons

This study investigates the unidirectional rotation of single molecule-rotors, crucial for nanoscale work. We compared two DMBI-based molecule-rotors on an Au(111) surface, exploring their one-way rotation induced by tunneling electrons and thermally-induced random rotation rates. By optimizing the parameters of temperature and tunneling current, we identified a narrow voltage range that enhances unidirectional rotation without inelastic tunneling effects. By the quantum mixing of the ground and excited states occurring at each tunneling electron transfer event through the molecule-rotor, the thermal energy can be projected in part on the excited states of the molecule-rotor to enhance the one-way rotation effect in a bias voltage range where inelastic tunneling effects are nearly absent.