The spectrum and term system of CI VIII

The spectrum of neon-like chlorine, Cl VIII, has been investigated in the wavelength region 100-6000 Å using the beam-foil technique and by means of spark and theta pinch measurements. 188 new levels, most of which are ascribed to the hydrogenic part of the term system, have been determined from 314 combinations. The levels belong to 32 configurations ranging from 2 s 2 2 p 6 up to 2 s 2 2 p 5 9 l. Term structure and coupling conditions have been analyzed. Interactions between levels of the 2 s 2 2 p 5 np, nd, nf and ng series and those of the 2 s 2 p 6 nl configuration are found to be prominent and have been investigated in detail. The experimental results are compared with isoelectronic analyses and with parametric and ab initio calculations. By applying the polarization formula to hydrogenic configurations, the centre of gravity ionization energy of the 2 s 2 2 p 5 2 P limit is determined to 2 813 823 ± 60 cm −1 .