Unidirectional Electronic Ring Current Driven by a Few Cycle Circularly Polarized Laser Pulse:Quantum Model Simulations for Mg-Porphyrin

摘要

A circularly polarized ultraviolet (UV)laser pulse may excite a unidirectional valence-type electronic ring current in an oriented molecule,within the pulse duration of a few femtoseconds (e.g.,tau =3.5 fs).The mechanism is demonstrated by quantum model simulation for |X> =|1 ~1A_(1g))-> |E_+> =|4 ~1E_(U+))population transfer in the model system,Mg-porphyrin.The net ring current generated by the laser pulse (I =84.5 mu A)is at least 100 times stronger than any ring current,which could be induced by means of permanent magnetic fields,with present technology.