The control of electron dynamics in molecules or molecular assemblies by irradiation is a fascinating research field. [1,2] Control of the photocurrents of molecular devices in the ultrashort time regime is essential for nanotechnology. However, fundamental issues remain to be clarified for the manipulation of electron motions, especially in large molecules such as those having aromatic rings. Aromatic molecules are characterized by delocalized p electrons that can in principle be controlled using UV/Vis light. One of the issues is how to control their rotation direction (ring current) using ultrashort UV/Vis laser pulses. It is unclear whether p electrons can be rotated along an aromatic ring by a nonhelical, linearly polarized laser pulse, though p-electron rotation can be performed using a circularly polarized laser pulse. [3] In the latter case, the rotation direction is predetermined by the applied pulse. If p-electron rotation is induced by a linearly polarized laser pulse, the rotation direction should be intrinsic to the molecule of interest because a nonhelical photon has no angular momentum. Therefore, its electron dynamics should reflect the asymmetry of the molecule itself.
We show here that the polarization direction of a linearly polarized laser pulse determines the initial direction of pelectron rotation in a chiral aromatic molecule. We then propose a pump-dump control method for determining