Interactions involving excited atoms will be investigated. The focus is on atoms in highly excited Rydberg states, which can accentuate usually unobservable microscopic effects. Attention will be directed toward quasi two electron atoms, where highly excited states can be of either pure Rydberg or mixed Rydberg - doubly excited state character. This permits comparison of the reactive properties of the two disparate states, which behave quite differently. Since black body radiation rapidly alters state selected populations, an apparatus will be used in which low absent temperatures can be maintained in the reactive region. This will also permit studies of interactions of atoms with black body radiation.
