The time-resolved photoelectron spectra of the $\mathrm{NaI}$ molecule, as well as the populations of the ${\mathrm{Na}}^{+}$ ion and the ${\mathrm{NaI}}^{+}$ ion have been calculated in this paper by using the time-dependent wave packet method. The results agree well with the experimental ones [J. Phys. Chem. A 101, 2555 (1997)]. It is found that exchange of the wave packets in the crossing area plays a prominent role in the process of photoionization. Two conclusions can be derived from the calculation: First, the population of the ${\mathrm{Na}}^{+}$ ion is approximately seven times that of the ${\mathrm{NaI}}^{+}$ ion when the pump and probe delay is $150\mathrm{fs}$ and, second, the vibrational period is about $700\mathrm{fs}$ and has an increasing trend with the increase of time.

• Received 8 December 2006

DOI:https://doi.org/10.1103/PhysRevA.75.042512