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 spectograph. More than 500 lines have been identified in the wavelength region 295 A to 2830 A as combinations between 106 levels of the configurations 3s' 3p5, 3s3p6, 3$ 3p43d, 4s, 4p, 4d, 5s and 3s3ps 3d. The level structure has been theoretically interpreted by means of calculations including configuration interactions. Energy parameters determined from leastsquares fits to the observed level values are compared with theoretical values obtained with Hartree-Fock wavefunctions from the Cowan computer code.

Stark broadening of Ca iv spectral lines of astrophysical interest

“…For the spin-orbit integrals ζ nl characterized by small numerical values and not adjusted in the fitting procedures we used the HFR ab initio values without scaling. Our results are close from those published by Ekberg et al (1990) and therefore we do not present here details.…”

“…For the IC calculations, we used the standard method of least-squares fitting of experimental energy levels programs of Cowan's programs. The experimental levels used in our procedure were the presented by Ekberg et al (1990).…”

“…The first compilation of energy levels of Ca IV, based on the previous cited works, were made by Moore (1958), Sugar & Corliss (1985) and Kelly (1987). Later, an exhaustive work about the energy levels of Ca IV was made by Ekberg et al (1990).…”

“…In the bibliography, experimental values about transition probabilities are not found. Calculus about oscillator strengths for the chlorine isoelectronic sequence was made by Ganas (1981), Verner, Verner & Ferland (1996), Wilson, Hibbert & Bell (2000), Biémont & Träbert (2000), Sing & Mohan (2001) Ekberg et al (1990). Träbert (2014).…”

“…Stark widths and shifts are calculated for an electron density of 10 17 cm −3 and temperatures T = 5000-300 000 K, and presented in the tables for T = 10 000, 20 000 and 50 200 K. As these data cannot be compared to others in the literature, we present an analysis of the different regularities of the values presented in this work. Ekberg et al (1990).…”