The rydberg constant

Abstract

The Rydberg constant is one of the most important constants of atomic physics bemuse of its connection with the fundamental atomic constants (e, h, m_c, c), and because of the high accuracy with which it can be determined. In this review the Rydberg constant is seen in its historical context, in relation to the spectra of hydrogen and ionized helium, and in relation to the atomic constants in general. Some of the problems which arise in its experimental determination are discussed and recent work using the techniques of high-resolution spectroscopy is described. A new technique—saturated absorption spectroscopy—is also described. This promises an improvement in accuracy by at least an order of magnitude. It is shown how work now in progress calls for a new definition of the base unit of length.