The spectrum of three times ionized calcium, Ca IV

Abstract

The spectrum of three times ionized calcium emitted from sliding spark discharges has been observed using 3-m normal incidence spectographs and a 2-m Ebert spectrograph. More than 500 lines have been identified in the wavelength region 295 Å to 2830 Å as combinations between 106 levels of the configurations 3s2 3p5, 3s3p6, 3s23p43d, 4s, 4p, 4d, 5s and 3s3p5 3d. The level structure has been theoretically interpreted by means of calculations including configuration interactions. Energy parameters determined from least-squares fits to the observed level values are compared with theoretical values obtained with Hartree-Fock wavefunctions from the Cowan computer code.