Abstract
Unimolecular multiphoton dissociation offers us a rather complete scheme where the transition from quantum mechanics to the classical regime can be experimentally followed. In the light of this idea, a new interpretation of the unimolecular multiphoton dissociation process is presented. The role that the intramolecular generation of instabilities and chaos may play in that process is discussed, both in single and double exposure experiments. Delayed double irradiation is also discussed and a criterion to define an effective single pulse notion in that kind of experiment is given.