Ultrafast Detection of Ring Currents in Molecules

After interacting with a circularly polarized femtosecond laser pulse, atoms and molecules frequently exhibit persistent ring currents. The currents can be as strong as several milliamps, and they induce impressive local magnetic fields up to several Tesla. It has been conjectured that such currents could remain coherent for picoseconds or longer, although the prediction has not been verified experimentally. We discuss several schemes for attosecond time-resolved measurements of ring currents, which would provide a powerful tool for exploring the evolution of molecular symmetry and chirality.