Spectrum and energy levels of singly ionized cesium: I Revision and extension of the Cs ii energy levels

Abstract

The experimentally determined energy levels of Cs ii have been revised and extended based entirely on recent observations of the spectrum. Most observed lines have been classified as transitions between 118 even and 167 odd energy levels. Of these 285 levels, 233 have not been previously reported. All the levels have been assigned designations in the jK coupling notation based on theoretical interpretation of the structure and empirical factors. Hyperfine splitting constants are given for 167 levels. By fitting polarization and extended Ritz formulas to selected Rydberg series, the Cs ii ionization energy has been determined to be 186 777.4(5) cm−1.