  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.
