Transient dynamics in molecular junctions: Picosecond resolution from dc measurements by a laser pulse pair sequence excitation

Molecular electronic devices are a promising future alternative to standard electronic switches due to their fast response on the pico-second time scale. An experimental scheme is proposed in order to correlate pico-second dynamics in molecular junctions to steady state current measurements. The time resolution is obtained using a sequence of ultrafast pulse pair excitations with a controlled time delay between the two pulses in each pair. The dependence of the steady state current on the delay time reveals the periods of molecular dynamics on the sub-pico-second time scale. The approach is demonstrated theoretically for a generic model of a single molecule based coherent electron pump. Theoretical analysis enables to correlate the steady state current to the underlying intramolecular dynamics.