Multiphoton dissociation and ionization of polyatomic molecules

Multiphoton absorption and the related dissociation and ionization phenomena add new possibilities to the study of excited states dynamics in atomic and molecular systems. Multiphoton transitions are predicted and observed whenever atoms or molecules interact with sufficiently intense electromagnetic radiation. What concerns the multiphoton absorption and dissociation of polyatomic molecules induced by IR laser radiation a series of studies has been done all over the world in the past decade, in view of the possibility offered to selective chemistry and laser isotope separation. Few examples of what has been obtained in some laboratories active in the field, in particular in Frascati labs for what concerns experiments in the discrete, in the quasi-continuum and in the continuum regions are here reviewed and discussed. (G.Q.)