Rydberg

Abstract

When an atom is in a state of sufficiently high principal quantum number that the valence electron is far from the ionic core, the atom appears hydrogenic. In such atoms, the valence electron is influenced mainly by the positive charge of the ionic core and not by its structure. The excited states of these hydrogen like atoms have been termed “Rydberg states,” “high Rydberg states,” or “simply highly excited states.” Rydberg states are interesting for two reasons. First, they are large and weakly bound, leading to properties peculiar to them. Second, much of their atomic structure and behavior in external fields can be understood on the basis of straightforward extensions of hydrogenic theory. Although the study of Rydberg atoms has a long history, the development of tunable dye lasers has led to great experimental advances and renewed interest in recent years. This is because the laser provides a simple and precise method of producing relatively large populations in specific Rydberg states. Thus, the chapter mainly discusses the work of the past few years with particular emphasis on the experimental work. This chapter is divided into three parts: (1) dealing with the spectroscopy of Rydberg atoms, (2) studies of their lifetime and collisional properties, and (3) a brief indication of the directions for future research.