ABSTRACT
This chapter describes the half reaction started from weakly bonded clusters. This half reaction technique is expected to provide unique information of reaction dynamics under geometrically constrained collisions. Such a constraint is essential to draw useful information about a potential energy surface (PES) near the transition state. Within the complete PES, the most important area is the region of the transition state, where an old bond breaks and a new bond forms. This part of the PES determines the fate of the reaction. A more popular approach to the transition state is by the use of photoexcitation/half reaction methods. Emission spectroscopy of the photodissociating molecule provides information near the transition state under a limited angular momentum condition. The most remarkable difference between the half reaction and the bimolecular reaction was the rotational distribution.
