Collisional Spectroscopy of Laser Excited Atoms

Abstract

This lecture will be devoted to the study of collisions between two atoms, both in an excited state. For their simple structure (only one external electron) and strong interaction with the light, we will consider here only experiments involving alkali atoms. Recently a great deal of work has been done also on more complex atoms such as calcium, strontium and barium. Collisions between two excited atoms were first observed using powerful discharge lamps as excitation sources, (for a review see for example ref./2/), but it is with the laser that high concentrations of excited reactants have been normally obtained. The study of collisions in a laser field is now a rapidly growing field of research 3–5. The simplest case of collisions between laser excited alkali atoms regards two atoms both in the first P state. A near resonance, of the order of few kT, between the colliding atoms and the final products of the collision is required.