A basic problem in atomic physics is the understanding of the interaction via collisions of isolated atoms. A new dimension in the study of such collisions is forming one of the interacting pair of atoms in a highly excited ("Rydberg") state by selectively exciting it just prior to the collision with a carefully-tuned laser. These Rydberg atoms have the property that one electron is almost completely decoupled from the parent atom, and acts almost as a free electron. It can thus be used to probe the interaction of electrons with molecules and surfaces. Such work will be carried out in the present grant. The properties of these atoms themselves will also be studied in electromagnetic fields. The results of this work will aid in our understanding and control of atomic properties.
