Control of photodissociation of the NaI molecule via pulse chirping

A dynamic pump control scheme is proposed to manipulate the predissociation process of NaI molecules in different reaction channels. A linearly chirped pulse is used to excite the NaI molecule, and a time-delayed infrared pulse is employed to modify the molecular potentials in the coupling zone. The predissociation branching ratio of the product from two channels can be controlled by tuning the chirp rate with a proper range of delay times. Furthermore, an additional ultrafast photoionization step is adopted to monitor the wave packet evolution and probe the possible modifications of the electronic potential under the influence of a chirped pump field to reveal the physical mechanism behind the control. Aulter-Townes splitting is observed at a proper chirp rate, and the dressed-state population can be controlled via pulse chirping.