Revised interpretation of the Na I EUV absorption spectrum

Abstract

Spectral data for neutral sodium were recently compiled by Sansonetti [1]. In that compilation, some of the energy levels of the 2p 5 3snl configurations were quoted from studies of the absorption spectrum in the Extreme Ultraviolet (EUV) region, while others were quoted from beam-foil and laser-spectroscopy studies of emission in the visible region. These two sets of data partially overlap. However, in [1] the energy levels observed in both types of studies were not recognized as being the same entities and were listed as different quantum states, interpreted in different coupling schemes. In addition, the analysis of the absorption spectrum was based on a oversimplified theoretical model and is incomplete. The present work identifies the energy levels commonly observed in absorption and emission studies and provides a consistent description of the 2p 5 3snl energy levels. As a result, about a hundred energy levels are revised. In particular, the connection of the quartet level system with the ground state is firmly established based on absorption studies.

Classification of the 5p5nln'l' LSJ energy levels of Cs excited by 30 eV electrons

“…Theoretical investigation of the 5p-core-excited autoionizing states of Cs is a complex task as the relativistic effects play a more important role compared with Na [1,2,3,4], K [5] or Rb [6]. The first attempt to perform the classification of Cs spectrum registered in an ultraviolet absorption experiment was made by Connerade [7] in jK notations.…”