Beam-foil Studies of Energy Levels and Radiative Lifetimes in Be I and Be II

Abstract
An investigation of the doubly-excited quartet levels in Be II and the displaced term system of Be I is described. Beam-foil spectra of beryllium (500-1 600 Å, 2 000-6 000 Å) showed several transitions which were assigned to doubly-excited Be II. A term scheme for these quartet levels is proposed. A number of the observed lines were also identified with the Be I 2pnl1L, 3L system. Radiative lifetimes have been determined for several excited levels in Be I and Be II.