Control of photodissociation branching using the complete reflection phenomenon: Application to HI molecule

The laser control of photodissociation branching in a diatomic molecule is demonstrated to be effectively achieved with use of the complete reflection phenomenon. The phenomenon and the control condition can be nicely formulated by the semiclassical (Zhu-Nakamura) theory. The method is applied to the branching between I($^2 P_{3/2}$) (HI $\to$ H + I) and I$^*(^2 P_{1/2})$ (HI $\to$ H + I$^*$) formation, and nearly complete control is shown to be possible by appropriately choosing an initial vibrational state and laser frequency in spite of the fact that there are three electronically excited states involved. Numerical calculations of the corresponding wavepacket dynamics confirm the results.