Laser-Driven, Surface-Mounted Unidirectional Rotor

We propose a design for a class of molecular rotors fixed to a semiconductor surface, induced by a moderately intense, linearly polarized laser pulse. The rotor consists of an organic molecule possessing a polarizable headgroup that is attached via a linear component to the surface. The polarization direction in parallel to the surface plane is determined so as to maximize the torque experienced by the molecular headgroup and, hence, the duration of the ensuing rotation, while also controlling the sense of rotation. We find that the molecule continues to rotate for many rotational periods after the laser pulse turns off, before multiple scattering by the potential barrier results in dephasing.