B i Absorption-Line Series at High Resolution

Abstract

The Ba i ultraviolet absorption spectrum has been reexamined at high dispersion by use of the second and third orders of the Argonne 3O~foot spectrograph. The principal series 6s2 `So-ós n~ 1P10 has been extended to n = 75; five series previously observed by Garton and Codling (1960), ascribable to two- electron transitions and converging on 5d2D312 5/2 of Ba ii, have also been extended considerably. A re- vised value for the first ionization potential (4203514 ± 0.05 cm') of Ba i is derived from one of these series. Configuration mixing and auto-ionization effects, revealed by the high-dispersion spectra, are discussed qualitatively