REACTIVE COLLISIONS WITH EXCITED-STATE ATOMS

In the context of molecular reaction dynamics, the study of elementary reactions with excited species has developed rapidly in the last deca des. This article reviews recent developments in the study of reactive collisions with excited-state atoms, under single-collision condition s provided by crossed-beam and low-pressure gas cell experiments. Appl ication of high-resolution laser techniques allows selective electroni c excitation of atomic reagents. This excitation is used to identify t he key features of state-selected and spin-orbit effects, on both the reaction cross-sections and product state distributions. The polarized nature of the laser field is used to gain a detailed understanding of the reaction dynamics and stereodynamics, through the alignment of at omic orbitals. Several examples are discussed in the light of current theoretical models, a detailed analysis of the data leading to the ide ntification of non-adiabatic processes taking place on excited potenti al-energy surfaces. New experimental developments will allow for an ev en deeper understanding of these elementary processes.