The absence of fine structure in the arc spectrum of silver

Abstract

The arc spectrum of silver, produced in a water-cooled hollow-cathode discharge, has been examined for fine structure with a variable-gap silvered Fabry-Perot interferometer in the region 8300 to 4000 A. Results for the resonance lines at approximately 3300 A. are also quoted. Silver consists of two odd isotopes 107, 109, and although 5s, 6s, 7s, 5p, 6p, and 5d terms have been studied no trace of fine structure has been found, in spite of very excessive over-exposing in many lines. All lines are extremely sharp and are worth considering as wave-length standards, being well distributed. Attention is drawn to the fact that the analogous spectrum of Cd II also shows no fine structure, so that it is concluded that the absence of structure is probably due to the electron configuration and not necessarily to smallness of the nuclear magnetic moment. This is remarkable, for penetrating s electrons are involved in some configurations.