Autoionization and ultrafast relaxation dynamics of highly excited states in N2

摘要

We have used the velocity-map imaging (VMI) technique to measure autoionization dynamics in molecularnnitrogen initiated by a train of attosecond pulses. The pump-probe measurements show clear evidence of ancrossing between potential energy curves of the highly excited N2n+ ion and of the N2n2+ ion. It is found that thenautoionization becomes energetically allowed when the two nuclei are still very close (∼ 3 A˚ ), in contrast withnobservations in other diatomic molecules, and that it can be coherently manipulated by a strong femtosecondninfrared pulse.