Motion and Manipulation of Molecular Motors by STM


Dr. Peter Jacobson, University of Queensland
This colloquium will be held at 11 am, 23rd August, in  Bldg.: Richards (05), Room #213
A fundamental component of molecular machines are motors that translate an external stimulus into usable work. Light-driven molecular motors rely on ultraviolet light to trigger a sequence of isomerization and helical inversion steps leading to the unidirectional rotation of the motor. While the rotational action of the molecule is confined to a small volume, the output of these motors has been successfully coupled to macroscopic objects. On the nanoscale, motorized molecules are envisioned as carriers of reactants or information.

In this colloquium, I will present new results on unidirectional molecular motors adsorbed on metal and semiconducting substrates. Individual molecular motors were imaged and manipulated using scanning tunneling microscopy (STM). These measurements provide insight into the dynamics of molecular motors with atomic precision. On metallic substrates, motors act more as reversible molecular switches than sources of translation. On semiconducting substrates, motors freely diffuse along the surface, a result of inelastic excitations and short-range chemical forces. This is the first work exploring light-driven unidirectional motors on semiconducting surfaces where excited state quenching is expected to be strongly reduced compared to metal surfaces.